I just tried out this new vacuum hose mod that smooths out the low end, which I got from the french Kawette forum: http://www.kawette.net/forum/viewtopic.php?t=19314
The IAP (Inlet Air Pressure) sensor has a hose on the left throttle body. The mod consists of a hose that connects both TB's at the carb synch fittings with the IAP hose coupled to the connector hose. This smooths out the IAP reading and balances out the vacuum pulse between the two TB's. Kawette forum got the idea from an Italian source, and they tried two other connecting methods with additional routes but with the same results... A smoother response at low rpm range without hiccups is noticed, as well as improved tractability, torque and throttle control. Some reported better fuel economy. Engine braking also seems to be reduced.
I really like the improvement so far. :thumb:

UPDATE: (post # 134 on page 7) After noticing that the IAP sensor fitting bore is larger than the two TB vacuum access fittings, I tried connecting the left tube on the smaller vacuum access fitting instead of on the IAP fitting, still with a T and the right tube on the other TB's vacuum access fitting. I had to raise idle rpm back up and it ran very poorly and sounded erratic. I pulled over and quickly put it back like I had it with the left hose on the TB's IAP fitting... I then put the IAP hose back on its fitting and connected both TB's without the T. It's also known as configuration '1' in the french forum, as some have reverted to. It runs at least as well now as with the left hose on IAP fitting and a T like I had it. I'd like to try out configuration '2' now, as shown in second pic... I had enough 5/32" (3.83 mm) vacuum hose to replace the thin, slightly short and bent IAP 6 mm hose as well. I was able to do it all in a few minutes with a slim pair of needle nose pliers.

Geez, there are tons and tons of members at that forum! I can't read French enough for real comprehension, but certainly this question has been asked.

There has to be a reason why this wasn't done on the stock bike... maybe they thought the cost of carrying 3 lengths of hose vs. 1 and 1 t-junction was too high.

Furthermore, does any other bike (specifically : more expensive) have this sensor hose attached to more than one TB?

I've been wondering the same thing, and what effect coupling the TB's on a non-FI twin would have... Cars read IAP at the intake manifold which has all the intake inlets together on a common chamber.
This mod stabilizes the IAP signal, by reducing the vaccum pulse width and by doubling its frequency.

Hmmm... This is a mod I may have to try!

I've been wondering the same thing, and what effect coupling the TB's on a non-FI twin would have...

I did it on my Triumph (T100) and it gave it better throttle response....

A quick question gents: What is blank plate with two bolts on it? It sits centerline of the valve cover between those two electrical connectors.

Red

I think I'll give it a try too. Do the french have any other secrets that you've managed to crack??:)

Red alert, I think that the aluminum plate you see is Invader's PAIR valve block plate. It's another mod that will keep an aftermarket exhaust from popping on decelleration. It seals the port that usually gets air from the PAIR valve to keep it from entering the exhaust.

For more info try a search on the forum for PAIR valve.

Invader -

Is that Tygon tubing you used?

No, it's nothing exotic... I just got one foot of available 1/8" (3mm) ID vinyl primer hose and a white plastic T from my Yamaha dealer. It works fine, but I'd like to get some nice silicon tubing.

PS: I then upgraded to 3/32" Goodyear vacuum tubing with a 3/32" T fitting.

Is the bike hard to work on?

No, but for easy access, you just need to remove wind screen, fairing, seat, gas tank and airbox... Here it is as seen from the side... She is a smooth runner now, and it's well worth it.

No, it's nothing exotic... I just got one foot of available 1/8" (3mm) ID vinyl primer hose and a white plastic T from my Yamaha dealer. It works fine, but I'd like to get some nice silicon tubing.

Silicone tubing will deteriorate on contact with gasoline and/or gasoline vapors...don't ask me how I know that! I know there shouldn't be liquid gasoline in these tubes, but when you shut the engine off, the vapor may creep up into them. There is a chemical resistance which also shows gasoline in contact with silicone as a "No" here:

http://www.watson-marlow.com/wmb-gb/p-chem-g.htm

You'd probably be best off just to use some regular automotive vacuum hose. It should handle any gas vapors fine, and it would color match with the original hose. Throw in a brass 'T' or 'Y' fitting if you want a really fancy and bullet proof set-up.

Thanks for the info on silicone tubing... A brass T fitting wasn't available then. The white 'plastic' one is light but fragile. Tygon tubing as used in RC is usually available in bright colors, but would be good and very flexible.
I'd like to try polyurethane tubing (available in transparent or opaque colors), also much better than regular rubber automotive vaccum hose with it's high resistance to oils, greases, fuels, vacuum, weathering, abrasion, tearing, pressure, impact, radiation, prolonged or frequent flexing, good tensile strength and high elastic memory. I could also upgrade the existing IAP sensor tube.

Thanks for the reply. I am contemplating picking up an 09 and i like to do all my own work.

I have a spool of the tygon stuff and have been using it for a long time on my gas RC planes, and while it is good, it does deteriorate (harden) and would certainly need to be replaced every two years or so.

I have a spool of the tygon stuff and have been using it for a long time on my gas RC planes, and while it is good, it does deteriorate (harden) and would certainly need to be replaced every two years or so.

Strangely enough, I used to use silicone for my 'gas' RC planes and cars...it seems to hold up well to the nitromethane, methanol and castor oil mix that they burned. But only lasted a few hours in gasoline! Go figure~!

You never know what's in gasoline these days!!!

Did this mod on my V. today. After riding around about 200 miles, A couple of things I noticed. After getting my exhaust, I noticed it seemed to take a bit more throttle to get me going smoothly from a stop, and sometimes it did not go so smoothly!!! After doing this mod, she seems to pull away much cleaner and with less effort. Seems to be a little smoother at low speeds as well, not that this was ever a major issue. Kinda feels like she pulls a bit easier with given throttle application as well. Whether I have gained any hp, I can't say, but I assume torque has improved a bit down low due to the easier starting. My mileage last fill up today returned about 60 mpg, with a few wheelies and a top speed pull. :yeahsmile:I'll report on mileage again if it has improved with normal day to day running. The mod took about an hour to perform, very easy, and cost me about $5 in parts from local auto store-1.5 ft 1/8" vacuum tubing (of which I have about 10" left over), and one 5/32" (3.96mm) vacuum tee. Till then, here are a couple of pics of my install. Thanks a bunch, Invader, for the info!!!:thumb::thumb:
Fukken cheers,
Erik!!!

I'm going to have to try this one out. I want some more wheelie power.

I just completed this mod and I have to say it's freaking amazing. Much less engine braking - I like that part. Better throttle response and smoother throughout the range. The bike is now scooter smoothe. I was amazed how hard it was to source the parts in my area. I thought this would be easy stuff to find. I must be in the dearth of auto parts hell around here. I almost gave up and check one more place and found the vinyl tubing that Invader used and the cheap plastic T. It all works, great post. This should go on a faq of recommended modifications.

I agree! We need a 'faqs' sticky. There are some really good ideas showing up here. It would be great to see them all in one place... :thumb::thumb::thumb:

So how do you get the Air Box of :huh: ? I got every thing disassembled until I got to the Air Box. Since I had a full tank of gas, it was balanced to shaky for the time it would take to figure out how to get the air box loose. I'll have m son come over tomorrow to hang on to it for me, but knowing how to detatch the air box would speed things up.

I just did this mod, but I didn't disassemble the bike. First, disconnect the OEM hose from the left vacuum port. Install the tee & the other two hoses & let 'em hang for a minute. Use a long, common (flat tip for you old schoolers) screw driver to gently work the rubber cap off of the right port, accessing it from the left side under the tank. Use a flash light (torch for you Euros), you'll see it.

If you're careful, you can actually get the end of the hose that connects to the right side to start on the right port from the left side. Then, you just need a pair of needle nose pliers with a bent tip. I used them from the right side, between the throttle cables & grabbed the end of the hose & just slid it on. It takes a little wiggling, but it'll go. The other side is very easy to reach, there's nothing in the way. Using pliers again, I just slid the second hose on the left port. Maybe fifteen minutes max.

Like these (on the right):

http://i59.photobucket.com/albums/g304/Bear_on_a_bicycle/00930429000.jpg

Thanks for the info. I'll give it a try tomorrow. :thumb:

...Since I had a full tank of gas, it was balanced to shaky for the time it would take to figure out how to get the air box loose...

When I took my tank loose I pulled it totally off, and had it sitting in my yard with a towel under it. No need to balance the tank, just take it all the way off. :thumb:

I ran my Versys 300+ miles in the mountains today with the split vacuum hose modification. The throttle response did seem smoother down low, but to be honest, I am not sure it was a truly big difference. I got a few pops on deceleration a few times, that was the only negative change. Synchronizing the air bleeds will be my next project. Maybe that will help the low-end response, too.

Has anyone tried running the IAP hose from both throttle body synchronizing vacuum ports? I ask because I would like to hook up my Scottoiler to the current IAP vacuum takeoff.

Just got the Mod done and tested it out. There is a considerable difference in the smoothness of low RPM throttle response and an equally smooth engine breaking response. Amazing what a cheap quick Mod can do to the performance, especially for a novice rider like me. :yeahsmile:

You mention that you've already modified the exhaust, then the vacuum hose. Has anyone here mod'ed the hoses with stock exhaust and air cleaner?

OK - I finally got motivated to try this out - But not so motivated I wanted to take the fairing, windshield, tank and airbox off. (and I don't have the fancy tools like Rick) So here is what I did:

On the right side of the bike reach in beside / between the throttle cables with a standard screw driver and pop the rubber cap off the vac port on that throttle body. Hold ~1 foot of 1/8" vac tube in your right hand and use your index finger to guide the tube onto the fitting.

http://i178.photobucket.com/albums/w269/coreyonline/DSCN3720.jpg

Push somewhat 'inward' with your hand and use your index finger to guide that force 'downward' onto the fitting. I was able to completely seat the vac tube with only a slight effort. Pass the unattached end of the tube between the top of the engine and the bottom of the airbox over to the left side of the bike.

Walk over to the left side and use the screwdriver (if needed) to pop the OEM line off the left TB. Also use the screw driver (if needed) to finish fishing the vac tube to the left side. Pull the tube snug and cut it about as short as you can but still have just a bit to work with.

Install a short length of vac tube on your "T" fitting, install the "T" fitting in the OEM line and hook the other arm of the "T" fitting to the line from the right hand TB. Lastly, hook the short vac tube to the left hand TB fitting and it's ready to go. You only need a screwdriver and a knife to cut the tube.

...and there you have it! No need for tank removal & all that mess. :D:thumb::thumb:

OK - I finally got motivated to try this out - But not so motivated I wanted to take the fairing, windshield, tank and airbox off. (and I don't have the fancy tools like Rick) So here is what I did:



Did the same thing today as you described, but also am aflicked with Frankenstein hands so I used a long flat ignition screwdriver to remove the cap on the left side of the TB almost all the way off and then used a needle nose plier from the right to pick it off so it wouldn't fall down into the deep receses never to be found again. I then used the pliers between the frame and the throttle cable to guide the new hose on and wiggled it in place. It worked great and I was done in 5 minutes, thanks to Cory's suggestion.

I do notice better response at lower revs, it seems to roll off smoother. I can't say I notice any difference in the engine braking though, which is one of the things that really bugs me about the V. I think I'm going to do the block off thing and change out the exhaust to see if that helps. I know with my XR650L, after removing the pollution control crap, opening up the air intake, exhaust and rejetting, it was like a whole different bike.

Cheers

I have tried them all and engine braking is no different. Remember that engine braking is a function of compression ratio and rpm. The only real solution would be a slipper clutch. I wonder if a Rekluse is available?

Super easy mod! Thanks! I rolled on down to my Ace hardware bought 1 foot of poly tube and a t adapter for $1.39. I went in through the sides with needle nose pliers and was done in less than 5 mins. It just started to rain a little here so I will post back with performance thoughts.

Thanks Again!

w00t!

I got it done with my Frankenstein hands (without taking the bike apart).

Even though the bike's new[ish], I was taught that it's good practice to cut tubes and hoses from fittings that might crack or bend easily (e.g., carbs, water pumps, radiators, etc.)

So, instead of prying the existing tube off the left throttle body, it helps to gently slice it off with a utility blade (you're going to shorten it anyway). The cap on the right comes off easily.

I'll be riding to work in the morning and we'll see how it works!

:thanx:

I'm not getting more exhaust popping with this mod... Many who have tried it have noticed a bit less engine braking, which is also affected by carburation. It's barely perceptible, and probably caused by the vaccum backpulse admitting some intake air through the coupler hose from the other cylinder while off-throttle.
At any rate, it does run better like this and it's good to see that it's working well for all of you... I figured it could be done without removing everything, but I had to get back because my airbox wasn't all the way down on the left TB from replacing my air filter. Make sure you get the crankcase breather hose back on properly when reinstalling the airbox.

Has anyone here mod'ed the hoses with stock exhaust and air cleaner?

My bike still has the stock exhaust, air filter, and everything else.

Engine braking is indeed a function of the motor, but some FI systems keep a small bit of fuel squirting on deceleration to avoid a sudden lean mixture in the catalytic converter. To quote the Sewer Urchin, "That's baad." It used to be done with dashpots on carburetors, now it is done with CPUs.

May I strongly recommend that anyone considering this modification take the time to go to an auto parts store such as NAPA and get the appropriate black vacuum hose? Take a vacuum cap with you and they can match the inside diameter. I also got some very nice, very small T-fittings there. Cost was only a few dollars. You really do not want to use hose material that is not designed to withstand direct contact with hot components and exposure to fuel or fuel vapor. ;)

I believe that I may do the airbox mod, sub-throttle plate removal mod, and block off the PAIR lines as described on the 650R website. I am also going to invest in the DIY exhaust as described by Versys08. Total cost will be less than $100.00 and should make a big difference on performance and hopefully by having the engine breath better, reduce the engine braking phenonomen somewhat.

Cheers

Does anyone have a sense of how this mod might effect the warranty?

Does anyone have a sense of how this mod might effect the warranty?

It would probably give them a good excuse to deny a warranty claim. If you have to take it in for service, change it back before you do.
.
.

Engine braking is indeed a function of the motor, but some FI systems keep a small bit of fuel squirting on deceleration to avoid a sudden lean mixture in the catalytic converter. To quote the Sewer Urchin, "That's baad." It used to be done with dashpots on carburetors, now it is done with CPUs.

May I strongly recommend that anyone considering this modification take the time to go to an auto parts store such as NAPA and get the appropriate black vacuum hose? Take a vacuum cap with you and they can match the inside diameter. I also got some very nice, very small T-fittings there. Cost was only a few dollars. You really do not want to use hose material that is not designed to withstand direct contact with hot components and exposure to fuel or fuel vapor. ;)

Engine braking occurs when off (or partly off) throttle, so it is dependent on the amount of air admitted at the throttle bodies. With the tube coupling both TB's at fittings past the throttle plate, some intake air is admitted from the other TB as the vaccum is sequentially balanced between the two via the tube...
The nylon tubing I'm using has more heat, vaccum and pressure resistance, is resistant to gasoline and is easily accessible from motorcycle/snowmobile dealers. It does get stiffer after a couple years but doesn't deteriorate as fast and is more abrasive resistant than rubber. I'll probably upgrade to some polyurethane tubing when needed.

Having done this mod a few days ago & ridden a few times, including to work, where I have quiet a bit of low speed riding, I like this mod. I doesn't completely eliminate the low speed jerkiness, but it damn sure makes it a lot better. The engine feel smoother to me when shifting, as well.

I really wonder why they didn't do this from the factory? There has to be a reason.

I love these kinds of mods!!!

The only problem with changing it back before dealer service is that you have to cut the original hose. Hmm....may wait til next year for this mod. Although, i sooo want to try it.

The only problem with changing it back before dealer service is that you have to cut the original hose...

There is no need to cut the original hose, not really sure why you would want to do that. :yeahsmile:

Connect the original hose to the single side of the "T" leaving it the stock length, and connect a couple of short new hoses to the vacuum ports on the throttle bodies.

Thanks for the tip, I did this mod the other day and noticed a marked improvement in low throttle setting smoothness.

Wardo

I just installed this mod a couple of days ago and really haven't noticed much of a difference in engine braking because, as mentioned numerous times in this thread, the engine braking is relative to compression ratios and of course a few other things.......
I have however noticed that my rpm's have dropped by 200-300. Most notably at highway speeds which would of course explain the increase in MPG that a few have experienced. I just filled up yesterday so I will try to report back with my mileage on the next tank.
I would have to say that in terms of cost/effect this mod is well worth the time .

I have however noticed that my rpm's have dropped by 200-300. Most notably at highway speeds which would of course explain the increase in MPG that a few have experienced.

That can only be from a reduced speed. The vaccum hose mod does not change your gearing.

Invader. I know that this mod does not change the gearing of the bike. That is obvious. Thats pretty insulting to think that I believe this somehow changes the gearing of the bike.....please, are you serious?! Did I mention anywhere in my post that I believed that this changed the gearing of the bike? My advice would be for you to read and fully understand before contriving your responses. But it did drop the rpm of the bike. I normally set right at 6000 rpm @ 80mph. NOW at 80 mph the bike hovers at or around 5700-5800 rpm. If you want me to get more detailed for you I can. I was just inputting my experience with this mod. I have not made any "gearing" changes to the bike so through deductive reasoning that can be the only explanation. If I had changed the gearing of the bike then that may explain......due to the fact the the reading at the countershaft would be different which would affect the speedo read-out so on and so forth. I'm sure you understand.

Just to let you know. I spend 95% of my time on the interstate commuting so I do have plenty of time to watch the tach/speed readout. In other words, I don't just putt around town and do a couple of accelerations up to 80mph just see what the tach reads. Consistency are the terms I measure in.

Oh my.

Scaryfast777, I don't think anyone was trying to insult you. The question raised by Invader is a valid one. I too, was wondering just how the rpm would change with this mod. I have seen a drop in idle rpm, but no change in operating speed rpm, and I am also curious to find out what could account for the change as mechanically speaking the vacum hose mod would not make a difference in rpm at a set speed.

With respect,

My apologies to Invader. I kind of went of the hinge there. Bad day...no excuse. Thank you Zeniac for calming the nerves a bit.
I wonder what kind of things may play into this. It makes no logical sense. I have actually noticed the exact opposite as you Zeniac. In terms of idle there is no change but there is in operating rpm. Does anyone think that this could somehow be related to differences in the rider and his/her influences on the bike. (i.e. rider weight, prior break-in procedure, clothing worn on bike and the aerodynamic influence that may play into effect or even the actual type of tubing/fitting used for the mod seeing that the actual diameter of the tubing could play an inter-related role in a different vacuum pressure).

Cheers and sorry again to Invader.

The RPM and indicated speed should always be the same on this bike. The speed pickup comes from the CS but no relation to gearing what so ever.

Invader was right on, just making a simple statement. I have no idea how you could get a different RPM to speed reading.

Now if you are getting the speed from a GPS, then it could change.

Engine rpm at a given actual speed is a product of tire circumference, primary drive ratio and final drive ratio. A change in any of the three is the only way that the rpm will be affected. Normal tire wear will actually reduce the actual speed due to decreased circumference.

Yeah... Indicated speed vs indicated rpm doesn't change, even when changing countershaft sprocket size. Final gearing and varying tire circumference only change actual speed. Varying temperatures may cause very slight fluctuations, but only internal transmission gearing, clutch slip, or a 'speedometer-healer' can change the relation between indicated speed and indicated rpm.

Head Wind VS Tail Wind ???

Head Wind VS Tail Wind ???

No... A head wind may make it harder to travel as fast as in a back wind but, come hell or high water, the relation between indicated speed and indicated rpm is always the same.

I upgraded the vacuum T with a larger GoodYear 5/32" vacuum T (#65614) with two 4" long 5/32" ID GoodYear vacuum hose, which improved the vacuum mod effects even more.

Invader,
Other than looking ultra clean, how did using the Goodyear 5/32 stuff improve the performance? I used some overflow tubing I had sitting around, and there was definitely a noticeable improvement in low speed smoothness.

Regards,
Wardo

Well, I was using some thin 1/8" ID gas primer line with a smaller T for it. The french forum had noticed an improvement by boring out the T they were using, as its ID is smaller than the hose and affected the IAP reading and the rate of balancing between the TB's, as verified with a vacuum gauge... I just noticed that it now runs even more smoothly.

I guessed that was your line of reasoning, but I just wanted to verify.

Thanks,
Wardo

Did the vacuum mod yesterday. 10 minutes and $4. My arse and ears tell me it's smoooooother:D

cheers,
/neil

That's great, Neil... Glad to see it's helping many. :thumb:
What type of T and hose did you use, and how long are the two lenghts?

The NAPA special. Black 5/32 vacuum tee and their goodyear hose. I think the right side TB length was 6" and left side TB was shorter, like 4". Kept the stock hose that goes to sensor the same length (didn't cut it).

512 miles of smiles! I know I'm the ONLY one here that hasn't put NEAR enough attention on work since I got the V last week......

/neil

I am slightly confused, but am I to understand this right:

If you are to use a larger diameter tube, the end results will be better?

It does seem to help more. I mostly wanted to have a T with an ID that's not too much smaller than the IAP sensor hose to impede its vacuum reading, as noted in the french forum source. I also went with the available 5/32" ID GoodYear vacuum hose which seems to increase the balancing effect, and maybe compensate for the T's restriction... It's a bit of a blind science still, but it works.

I finally got around to doing this mod. $3 in parts at Advance Auto, Napa didn't have any of the bits I needed.

On my first 5 minute ride I didn't have gear, and some bozo dropped diesel fuel all over my entire neighborhood, so I was really paranoid. At first I didn't notice anything and was kind of bummed out. I think I was expecting more power, or less shaking and bogging at around 3Krpm.

I came back home and got dressed up in my riding gear. On the second ride I rode for a half hour and really noticed the difference, less engine braking. This really helps to eliminate the herky-jerkiness on the low end of the RPM range caused by engine braking. I think this mod makes it much easier to ride the bike smoothly. I like it. I don't think it increases power any, or makes the bottom end much more useful, just smoooooother when going on/off/on throttle. This would be a great mod for a noobie as being smooth will help one not take a spill in a turn. You can really feel the effects of less engine braking. Instead of pulling in the clutch when coasting, you can now leave the bike in gear and still maintain some momentum.

Luke

Okay I did the mod and it is not near as excitiing as I thought it would be. First thing I had to do is to set my idle back up to were it was before the mod. It now idles a little rougher then it did and is a little nosier at idle then it was. My Versys never ever had any kind of hicup to it and it still doesn't. Now the part I like is the little extra snap it has now. When you twist the throttle it takes off nicely. Not like it had 10 more horse power but just enough that you can really feel it. For a free improvement it is pretty dog gone good. Now as far as engine braking ,it has no effect on braking at all. There is no way this mod can change engine braking. When you let off the throttle the Versys will stop it's self. I will video some this weekend to show how it performs and that it still has big time engine braking. I am not sayiing that you guys are crazy just should lay off the weed before test riding. :stickpoke: It is much better to wait until you are writing this stuff on these forums. :D Thanks for all the info. :thumb:

Now the part I like is the little extra snap it has now. When you twist the throttle it takes off nicely. Not like it had 10 more horse power but just enough that you can really feel it. For a free improvement it is pretty dog gone good.

A few weeks ago I removed the sub-throttle plates since I was already fiddling with the airbox. It was a very easy job—once the airbox was off, natch. I am one who usually subscribes to the philosophy that the engineers at the factory know more about their bikes than I, so I was hesitant to remove the plates, but it can easily be reversed.

WHAT A DIFFERENCE! I did not realize just how sluggish the low-end response was until riding after this modification. My complaint with the Versys' low-speed response was accelerating after slowing down, such as merging onto a road. There was always a slight delay that I had to work my brain/hand coordination around. Now the bike accelerates as all my other bikes. No extra thinking, just go.

I did the alternate vacuum hose modification before removing the sub-throttle plates and can attest that the former modification pales in improved response as compared to the latter.

Now as far as engine braking ,it has no effect on braking at all. There is no way this mod can change engine braking. When you let off the throttle the Versys will stop it's self. I will video some this weekend to show how it performs and that it still has big time engine braking. I am not sayiing that you guys are crazy just should lay off the weed before test riding. :stickpoke: It is much better to wait until you are writing this stuff on these forums. :D Thanks for all the info. :thumb:

The engine still slows the bike, no doubt, but imho it doesn't jerk the bike down nearly has hard as prior to doing the mod. I believe a lot of the smoothness we're all enjoying is a result of the engine not braking as hard when making minute adjustments to the throttle at low speed. I used to have to pull in the clutch when just coasting because the V has a lot of engine braking, but the first thing I noticed after this mod was a lot less slowing down in gear, off the gas.

I never smoke before I ride.

It will be super easy to cap off the tee and hose going to the right TB, I'll do this on my next ride and report back with my opinion.

Luke

pretty good mod.... i just did it, costed me 0... lets just say 1 or more vehicles around here may or may not shoot wiper fluid anymore! i think i noticed a bit more torque too

My ride home consist of a lot of curves and hills. The Versys engine braking makes it a lot of fun. Do not have to use the brakes very often. It was no different this evening then it was this morning. Same engine braking it has always had. :thumb:

I did mine today as per your guide. I have only been riding the V for less than a week, and the improvement was obvious to me right away. Thank you! A very nice $5.25 mod. I did it quite easily albeit with some fiddling, with the tank in place.

:clap::thanx::clap:

I upgraded the vacuum T with a larger GoodYear 5/32" vacuum T (#65614) with two 4" long 5/32" ID GoodYear vacuum hose, which improved the vacuum mod effects even more.

Sub throttle plates???

WOW!! I just did this mod and it smooths it out so much on the low end. WOW!! I still cant believe the difference it feels like a whole new bike.

Wow I still cant get over the low end difference. I just filled up and 52 MPG and I ride aggressivly. It went up 10 MPG with the Turbo muffler, DNA air filter, and the IAP sensor upgrade I see a 10 MPG differenc. WOW!!! So I recommend doing at least this IAP mod if not all. THANKS invader you are the MAN!!! and a picture is worth a thousand words on that french website.

Wow I still cant get over the low end difference. I just filled up and 52 MPG and I ride aggressivly. It went up 10 MPG with the Turbo muffler, DNA air filter, and the IAP sensor upgrade I see a 10 MPG differenc. WOW!!! So I recommend doing at least this IAP mod if not all. THANKS invader you are the MAN!!! and a picture is worth a thousand words on that french website.


I don't mean to sound skeptical, but 10 mpg?? would you mind backing that up with numbers (like how many miles you traveled on a tank & how many gallons it took to fill it back up)?

I've read so many people claiming to get great mileage, but rarely see numbers to back up their claims. My bike has consistently got 46 to 48 mpg, even with the 16t sprocket & this mod. I just did a little over 200 miles today. I filled the tank just before leaving, 192 miles on the trip meter & 4.1 gallons to fill up. On the way home, I filled up again at exactly 190 miles & 4.1 gallons.

:thumb:

BEAR it was 205 miles to the tank and the fill up was 3.912 gals to be exact. I also do a lot of slow riding thus upping the MPG. There are times when I ride like its stolen but not a lot.

WOW!! I just did this mod and it smooths it out so much on the low end. WOW!! I still cant believe the difference it feels like a whole new bike.


Which mod? Plates or vac tube?

So BEAR I figured 40ish to 50ish is a ten mile to the gallon increase. Also keep in mind I am at 6200 ft and I need every ounce of MPG I can get since I have less air up here.

Well, not sure about the engine breaking...... but this mod does work, after a couple hundred miles, the front wheel definitely seems to comes up easier, and the bottom end is easy to work with.

The IAP mod antman325

Luke Jt how do you wheelie is it popping the clutch? or what do you do I guess we need a side bar for this discussion

Just a firm roll on in first or second gear and it comes right up (I'm 6'2, 240lbs). I'm no wheelie expert, I just enjoy rolling on the gas and having the front come up a bit when the time is right. I'm more aggressive in the dirt. :) I don't know why, but the tee mod seems to help.

So BEAR I figured 40ish to 50ish is a ten mile to the gallon increase. Also keep in mind I am at 6200 ft and I need every ounce of MPG I can get since I have less air up here.

So what kind of range & how much to fill up before the mod?

Going from 46-47 mpg to 50-52 is not 10. It is a nice improvement, but not 10.

:D

I guess the reason I'm a little skeptical is I've done the mod & saw no real improvement. Maybe 1 mpg, but that could be attributed to any number of factors...

I get the best mileage with my wife on the back, 50mpg. I usually get 48mpg. Worst fill up was 45mpg.

I get anywhere from 50 to 54mpg. I might get less with the mod because I like hitting the throttle more now.

So Lukejt must ride a little harder without his wife on the back!

After running through a number of tanks of fuel I have neither seen any MPG change nor noticable improvment in power, although seat of the pants tells me the motor seems to run a bit smoother at lower RPM. On the negative side, I do seem to have more backfiring, especially after comming off of a hard run and slowing to a light or stop sign.

Has anyone done this mod with the throttle plate mod? How does it compare to stock?

Has anyone done this mod with the throttle plate mod? How does it compare to stock?

See my reply midway down the previous page.

Just a firm roll on in first or second gear and it comes right up (I'm 6'2, 240lbs). I'm no wheelie expert, I just enjoy rolling on the gas and having the front come up a bit when the time is right. I'm more aggressive in the dirt. :) I don't know why, but the tee mod seems to help.

I like to take rides at dusk, and it was pretty cool out last week. Today it was hot, and the front wheel was much harder to pull up with just a roll on. Cool air = more power. :) Today I found that I need to dump the clutch to get some action (be careful, the V has a really short wheel base), but on a night ride when the air is cool the bike is very frisky in 1st and 2nd gears.

Went to Advance Auto and picked up the 5/32 tube and T... ofcourse the lazy ass that I am, I didn't take the route of removing the tank and everything else. I opened the right side 5/32 cap that covers the vacuum line...and the dang thing fell down there somewhere as I couldn't get it to cleanly come out! :censored:

Nevertheless, got the rest of the mod done and took it out for a spin....definitely a difference guys! Seems to roll off a lot smoother in first and second than previously. I'm sure I will feel it easier today when I am on I-40 in peak hour traffic!

Went back to Advance Auto and picked up a replacement for the 5/32 cap....just in case... the OEM one would have probably fallen off or melted (?) off by now!

I have over 9,000 miles on my V and I just made this modification with 1/8" hose and a plastic T fitting. I didn't take anything off the bike and just used 2 pair of really long pliers that I have like the one's someone else showed a picture of. I have the same exact ones. Maybe it's just in my head but to me the bike seems to accelerate alot faster when you really get on it. I also noticed that I have to adjust my throttle play when I was down in that area. I've never adjusted it and it has alot of slack like 1/4".

*WARNING... Negative comment follows* I did this mod today after having put 2400 miles on my Versys which is bone stock in the engine department. Guys I have to say, while I did notice slightly ,and I emphasize slightly, better throttle response off of idle, I also found that overall it felt like I lost power. Is that possible?

After hammering it for about 45 minutes to include roll ons, 1st to 6th full speed runs, cornering and rolling on, wheelies, and just plain riding it hard, it felt slower to me. I came back home and switched it back and immediately noticed more get up. The front wheel felt light again under hard acceleration where with the mod, I felt like I had to pull back as I accelerated to get the front wheel to feel light. Engine braking felt unchanged.

I was not impressed with the results.:thumbdown:

It should have improved throttle responce. My Versys has quiet a bit more pick up and I really like the mod. I do not understand why you would be the only one it did not help. You sure you do not have a vaccum leak in one of the lines?

Odly enough, i had my bike dyno tuned before and after this mod. only becasue i noticed it was slightly lean at about 6 k so i took it in for a free re-do ( while in the mean time i had done this mod) i had lost .6 hp on the second dyno. there is a million other factors that could be involved so dont take my word for it

I know I rained on the parade. Sorry but that was my experience.

It doesn't increase power. It makes it run more smoothly and less jerky at lower rpm's, giving you better low end tractability and improved throttle control.

Ive just carried out this mod. Only diffuculty is getting the vacuum pipe on. I did manage with a bit of stuggling and a long flat screwdriver, so i didn't have to remove anything.

This mod made a VERY notable chage: WAY less jerkiness at low RPM and less engine breaking when closing throttle.

The throttle response is now a lot smother and less harsh. Helps a great deal when riding at low speeds through traffic.

The mod will not increase fuel mileage ,horse power or decrease engine braking. It does add a nice snap when you open the throttle. Sometimes when I am playing around I like to power out of the corners and I can really tell the difference when I nail the throttle. it is like going from carb with no throttle pump to one that has one. To me it does not idle any different or is not any smoother. ;)

A couple of people have mentioned backfiring on deceleration after the mod. How many of you have experienced this? I want to do the mod this weekend but sure don't want the farts on decel.

Who said that? Mine doesn't backfire any more than before the vacuum mod...

No backfiring here. However, my pipes seem more blue since the mod....but maybe I didn't pay attention and it's just normal.

First post for me here but I am ManVersysNature over on Advrider. Stumbled upon this forum by accident looking for info on my V. Great site so far.

I did this mod tonight and I am so happy with it. I think it totally transformed the bike. It is so much smoother and seat of the pants feel tells me there is less engine braking. I agree with others that this mod shouldn't really change engine braking but it is just a sensation I guess. I didn't notice any changes in my idle or backfiring but I only took it out for a 10 minute ride.

On a side note I also modded the black fairing trim that buzzes so much. I used stainless steel allen head bolts and nylon lock nuts to mount it instead of the cheap OEM fasteners. No more buzz now the bike is damn near perfect. Seat goes to spencer next.

Do this mod you will not regret it. As far as install goes I had to pull the air box since my hands are just too big to get under there. It was a pain to pull the airbox up but I learned alot about the bike doing it.

Thank you to whomever discovered this mod you have a lot of ingenuity that is for sure.

Right on, XCRider. I'm glad you like the mod as well... I just don't know where the idea that it changes idle quality, and that it makes it backfire more comes from.

I did this mod last week and noticed an improvement in overall smoothness. I also believe the reduced braking on deceleration is real. I had the local dealer install the 16 tooth front sprocket mod ($33.00) yesterday and between that and the vacuum mod I now feel the bike is more drivable and much less herky jerky. I don't have to shift as much now.

I am using the Versys at the Keith Code CSB course. This mod has made the bike that much better. This bike is so much fun and after my experience at the course today I think it would be great at a track day.

my V at the Cali Superbike course:
http://www.sport-touring.net/forums/index.php/topic,30072.0.html

I am using the Versys at the Keith Code CSB course. This mod has made the bike that much better. This bike is so much fun and after my experience at the course today I think it would be great at a track day.

my V at the Cali Superbike course:
http://www.sport-touring.net/forums/index.php/topic,30072.0.html

Something I'll have to look into someday. Where I live there is very little in the way of training options. Next summer, I plan to go to Chicago and see if I can tak the SRTT (Street Riders Technical Training) course through Ride Chicago.

After I passed my M2 Exit Course here in Ontario - I asked the instructor where I could go for more training. He looked at me with the ol' dusty cow poke look, spit out his chaw and said, 'Man, you are one in a million'. He suggested I take the Track Day school at this nearby track. But, other than that there wasn't much in the local area.

Off topic - sorry. Just wanted to say that is great - I'd love to take that course.

I just did the vacuum mod today.

I think it did make some difference, seems smoother at low speeds, and the small glitch I had on take off from a dead stop seems to be better.

I can't really tell any difference on top end or wide open acceleration bursts, but there seems to be some more torque right off the bottom.

I specifically checked for backfiring, and there is none.

I was able to complete the mod without removing anything from the bike. A pair of really long nose pliers to reach the right throttle body vacuum port, and same thing to put the hose on. The left side stuff is easy to reach.

Seems to be a good mod, thanks for posting.

just did the mod. So far I like it. The only difference I notice is that the ride is much less jerky when going from engine braking in gear to throttle on. (like coming up to a red light, but then it turns green). It's smooth like butter now.

I did the mod and found too that the low end is much smoother and responsive. I live at 1500m (5000') and had backfiring thro the TB before the the mod and almost nil after, so I'm happy.

Also manged without removal of the tank.

A warning though, I initially tried the mod with clear plastic tubing and it actually lost out above 6000rpm. I suspect the tubing collapsed under high vacuum and hot engine conditions. With the proper tubing, it has a noticelable improvement at low to mid rev range as said, and certainly no worse at the top end, maybe smoother/more responsive.

Overall, it makes for a better commuting experience, where one is in heavy traffic and on/off the throttle at low revs all the time.

I did this mod last week and noticed an improvement in overall smoothness. I also believe the reduced braking on deceleration is real. I had the local dealer install the 16 tooth front sprocket mod ($33.00) yesterday and between that and the vacuum mod I now feel the bike is more drivable and much less herky jerky. I don't have to shift as much now.
Did you get that sprocket and install for that price? I have been wondering about the highway rpm's for the 16 tooth and what the part number is.

Thanks

Well I'll be damned. I did the vaccum mod last night and damn if it didn't smoth out the low end throttle response. I wish I knew exactally how this works. Anyone one know the details?

I did it yesterday too and was wondering exactly the same thing. There was very little difference except smoothing out the low end and a little bit less engine braking.

*WARNING... Negative comment follows* I did this mod today after having put 2400 miles on my Versys which is bone stock in the engine department. Guys I have to say, while I did notice slightly ,and I emphasize slightly, better throttle response off of idle, I also found that overall it felt like I lost power. Is that possible?

After hammering it for about 45 minutes to include roll ons, 1st to 6th full speed runs, cornering and rolling on, wheelies, and just plain riding it hard, it felt slower to me. I came back home and switched it back and immediately noticed more get up. The front wheel felt light again under hard acceleration where with the mod, I felt like I had to pull back as I accelerated to get the front wheel to feel light. Engine braking felt unchanged.

I was not impressed with the results.:thumbdown:

I was thinking the same thing. Quite noticeable pulling on the highway. I'm gonna race my brothers Harley Sportster (1200cc). We've run many times and the results have been very consistent (His ass handed to him!). Haven't changed it back yet because I love the smoother low-end response. I was starting to think I was the only one that noticed it. Anybody else?

At least this mod is easy to reverse!!!:D

I was on I-40 this evening stuck in peak hour traffic...this mod certainly smoothes out the deceleration / low end response to a point where I wasn't as pissed off as I would be usually.. :D It made for a comfortable / predictable ride...

For my skill level and my requirements from this bike, I dont think I will miss 1 - 2 HP of peak power IMHO....just my 2 cents...

I don't believe it is really affecting the engine braking as it is actually smoothing out the deceleration. IMO It does affect both low end acceleration and deceleration. I like it... :clap:

I did this a couple of days ago.

5 minutes work, $3 in parts.

Hint: Do it all from the left side of the bike using a pair of long needle nose pliers.


It doesn't affect engine braking at all.

All it does is smooth out throttle response at low RPM. At it does it surprisingly well.
It makes slow speed handling a little easier to modulate.
Above about 2K RPM, it has no effect whatsoever.

A good mod.
Thanks for sharing.

Did you get that sprocket and install for that price? I have been wondering about the highway rpm's for the 16 tooth and what the part number is.

Thanks

The sprocket I ordered from the dealer, part # 13144-0038 $33.99 and $33.00 for them to install it. I went on a 210 mile trip down the Blue Ridge Parkway on Monday and averaged a little over 58 mpg. At 5000 RPM I'm doing about 78 MPH. Hope this helps.

Relation between indicated RPM and indicated speed doesn't change when switching to a 16T. Actual speed increases by 6.66%, which reduces speedometer error from about +8% down to +1%. Odometer error goes up to about -6%, so you can add 6% to odometer reading and MPG...

What size hose are you guys using and feeling no difference. You have to use something of equal size for volumeteric air flow.

There is another post that says 1/8 inch inner diameter. Make sure it is sturdy hose that won't collapse. I used fuel pump hose as I couldn't find any vacuum hose close to 1/8 inch ID. I finally found some 7/64 at Pep Boys. I found a 1/8 inch tee though....go figure.

I used 5/32 vacuum hose and a 5/32 tee, equal length tubing for each side (dunno if that matters or not...).

I'd say equal length of hose, plus the right size and grade of pipe are all important. As I'd said in earlier post, I used chepa hose and saw a drop in power above 6k or so. With the right hose, it's back to nomal or better at the top end, plus the benefits at the bottom end everyone talks about.

As a matter of interest, I suspect two longer hose meeting in the "T" will be slightly better than two shorter bits. I seemed to find a small improvement on experimenting, but was hard to tell...

I used 1/8" T with 7/64" automotive vacuum hose (stiff thick hose).

I did not use equal lengths. And got good results. I do believe the pressure inside all the hoses will equalize so lengths shouldn't matter.

(similar to hydraulic pressure in brake lines)

I'm not sure why you guys are bothering with the T. The IAP story is a red herring. It makes no difference to the sensor if one or two TB's are hooked up to it. What this mod does (and invader does mention it initially, but it seems to have gotten lost in later posts) is create a TB crossover, bypassing the TB vacuum equalizing circuit (bypass screw). If you simply link those two ports with a vacuum hose, you'll get the same effect.

The shorter the hose, the better your vacuum will be equalized.


Gustavo

When I discovered it on the french forum, experimentations with different vacuum configurations had evolved to the IAP sensor reading a more stable and balanced vacuum signal of twice the frequency, on a T between both TB's. In the original Italian forum source (now at 37 pages), 'Mox's final fine-tuned and vacuum gauge verified configuration uses 2 T's with a 4 mm hose between both T's, and 5 cm long 6 mm hose from IAP fitting on TB to the T and from the other TB to its T.
(5/32" = 3.83 mm) I just realized that the IAP fitting bore is larger than the two vacuum access fittings, so I connected both hoses to the vacuum access with the plug on the IAP hose fitting.

http://www.er6italia.com/vbulletin/showthread.php?t=3802&page=20

This mod and setup in general has a lot to do with how smooth the engine is especially below 3000rpm.

I have an extra T in mine above the 2 throttle bodies T and before going to the IAP sensor. I connect a vacuum line to a 1-1/2" x 6" PVC reserve vacuum tank for my cruise control.

Over the few days I have been trying to sort this out, vacuum leaks have shown up and caused eratic engine and even FI light. So no leaks is very important.

Gustavo has opened the door for a better setup in my case and I may try it next, that is to just connect throttle body 1 to 2 (in my case with a T) and hookup my RVT to that T. But maintain the original single throttle body 1 connection to the IAP, and thus no leaks.

*WARNING... Negative comment follows* I did this mod today after having put 2400 miles on my Versys which is bone stock in the engine department. Guys I have to say, while I did notice slightly ,and I emphasize slightly, better throttle response off of idle, I also found that overall it felt like I lost power. Is that possible?

After hammering it for about 45 minutes to include roll ons, 1st to 6th full speed runs, cornering and rolling on, wheelies, and just plain riding it hard, it felt slower to me. I came back home and switched it back and immediately noticed more get up. The front wheel felt light again under hard acceleration where with the mod, I felt like I had to pull back as I accelerated to get the front wheel to feel light. Engine braking felt unchanged.

I was not impressed with the results.:thumbdown:

your not alone.........changed mine back also....lost it's snap.

So what kind of tubing and tees did you guys use?

So what kind of tubing and tees did you guys use?

automotive. Whatever brand they sell at the local parts store (Advance Auto Parts)

your not alone.........changed mine back also....lost it's snap.

Have to say, that although I did notice the mod smoothed out the 2-3k RPM rumble, I did notice a definate lack of "snap". I was writing it off to a dirty air filter, but after reading that you guys had noticed the same, I reversed the mod, and I must say... the bike is much livlier again. I used a pair of long surgical clamps to do the mod, and to reverse it. It takes all of 2 minutes with tank on. It is staying stock, rough low RPM be dammed, I like that kick!

After noticing that the IAP sensor fitting bore is larger than the two TB vacuum access fittings, I tried connecting the left tube on the smaller vacuum access fitting instead of on the IAP fitting, still with a T and the right tube on the other TB's vacuum access fitting. I had to raise idle rpm back up and it ran very poorly and sounded erratic. I pulled over and quickly put it back like I had it with the left hose on the TB's IAP fitting... I then put the IAP hose back on its fitting and connected both TB's without the T. It's also known as configuration '1' in the french forum, as some have reverted to. It runs at least as well now as with the left hose on IAP fitting and a T like I had it. I'd like to try out configuration '2' now, as shown in second pic... I had enough 5/32" (3.83 mm) vacuum hose to replace the thin, slightly short and bent IAP 4 mm hose as well. I was able to do it all in a few minutes with a slim pair of needle nose pliers.

I was wondering if the mod has more of an effect with aftermarket down pipes where the x-over has been deleted. With the stock downs and can, my bike suffered performace losses with the mod, and I am not really able to explain why. Theoretically, there shouldn't really be either a loss nor a gain in performance... just smoother revs... right?

Dunno, that's why I asked what material the guys who lost performance used. You guys used vacuum hose right?. By less snap, do you mean the throttle is less like a light switch?

I can easily loft the front wheel now in 1st-3rd with just a roll on, but I've also installed a slip on.

Have you guys read my post #134?

Dunno, that's why I asked what material the guys who lost performance used. You guys used vacuum hose right?. By less snap, do you mean the throttle is less like a light switch?

I can easily loft the front wheel now in 1st-3rd with just a roll on, but I've also installed a slip on.

I was using Invader's initial reconfigure of 5/32... exactly as seen in the photo. The motor seemed a little down on power untill till 5k, then it surged.

http://www.kawasakiversys.com/forums/attachment.php?attachmentid=707&d=1218619706

Have you guys read my post #134?

Yes.

Since I found it better in the stock formation, I am not sure there is any point in reconfiguring it for me. I do however, love watching you tinker!

I have returned to the original hose configuration. The bike seems a lot more responsive to throttle variations, and a lot more easier revving. Acceleration and performance seems much better. Im going to stick to the default setup.
It was worth experimenting though.

I as well have returned the TB vacuum to stock config. I, just as a few others, had began to wonder if the bike was developing a problem and just wrote it off as something else. I really didn't notice a big difference when riding solo, but when riding two-up it was very noticeable. Especially when taking off from a dead stop. The bike felt somewhat starved and I did notice that at highway speeds in top gear, I would really have to put more into the manipulation of the throttle for accelerations. I didn't take a hard measurement of how much extra throttle play I had but I do know that my hand position would sometimes be at a more severe angle which was truthfully a little un-comfortable during long stints on the highway. I found myself having to re-adjust my hand to "level it off" all of the time, which I had never really had to do before.
All that I have mentioned above and more led to some concerns until I re-visited this post yesterday and read that some people had also experienced the same issues. I went out to the garage, set back to stock config and took a 20 mile ride into town. I was amazed! The old bike was back. Snappy throttle response and no loss of power down low. As mentioned before, I think it was fun to experiment with and it was easy to set back to stock. Probably a great mod for first time riders that want to make getting to know the bike a little easier. (Not that its some huge uncontrollable power-monster)
For now I think I'll trust the engineers that designed this bike and engine configuration. I'm sure that they have this bike setup the proper way and used things like DOE to reach the proper setup with both safety and performance in mind.
BTW, during the extent of my experience with this mod I noticed no huge difference in MPG that could be contributed to the different setup (1-3 mpg difference per tank). I did notice more back-firing on decel and a HUGE lack of power on accel.

Interesting. I'm starting to wonder if this mod is like a band-aid for incorrectly setup TB balance/calibration. I'll try it back in stock configuration as well. I rarely ever spend much time below 3k, where the mod seems to smooth things out and make the biggest difference.

I've got a heavy wrist, I haven't noticed much loss in power, except for this...my bike is MUCH peppier when it's a bit cool out. Like 70 degrees. On hot days lately it seems sluggish, hard to pull the front wheel up. I wonder if this could be caused by the vacuum mod, or if it's just normal behavior, I know all bikes feel more powerful when it's cooler out.

With the mod in place, I don't have any backfiring on deceleration, and throttle response seems pretty good, almost like a light switch at certain rpms.

Which configuration are you now with, Lukejt? As I realized recently, it won't run nearly as well with the T and the left hose on right hand TB fitting. Configuration '1' works well... See post #134 on page 7, which I've also added in post #1.

Config 2.

I'm thinking about adding a small 12V solenoid and a switch to shut off the vacuum between the two TBs. Kind of a street and trail setting. Has anyone tried this to see how the ECU accepts the vacuum change on the fly?

LukeJt cold air is denser when it is cold so it will fell a little more snappy. I dont know if my gas tank is leaking but I get real crappy gas milage in town I dont know if its because I have a lead wrist or I cracked the feul line and its a slow drip. I did a 200+ mile ride on Sunday and I averaged 52 MPG but I had a couple triple times wink wink with a passenger. So that migh affect the MPG. Food for thought.

Config 2.

Config 2 is the one with 2 T's. Is that how you have it now?

Oh, I've got one tee. On my next ride I'll try it both stock and w/tee back to back.

Ok well, like I mentioned (see post 134 on page 7), you should just have the IAP sensor hose on its original fitting, and have a coupler hose on both TB's without the T (Config 1), or with 2 T's (Config 2). The IAP fitting bore is larger than the TB vacuum access fittings bore.

For now I think I'll trust the engineers that designed this bike and engine configuration. I'm sure that they have this bike setup the proper way and used things like DOE to reach the proper setup with both safety and performance in mind.
DOE is for us aerospace dorks, I think in the motorcycle business they probably just go ahead and build the sucker ;-)

Darth lefty, DOE is used in many aspects of R&D and engineering fields, not just aero. BTW, what do you think DOE stands for? No hard feelings..... just wondering? You know how those Japanese are. Everything has got to be perfect:)

This is worth a read, it is about an FJR, but one of the posters designed fuel injection systems and he is urging another not to modify their IAP/MAP sensor plumbing. I think I will change mine back now after reading this info. I sent him a private message asking his opinion on the Versys mod, I will let you know if he comments.

One comment: It is NOT a good idea to tee a vaccuum source into the MAP signal line. I would never recommend nor condone that. It might not cause any problems on the surface but it is best to not take the chance. The plumbing of an additional vacuum "volume" into the line going to the MAP sensor can cause signal oscillations and signal errors in many speed density fuel injection systems. This situation with the MAP signal has been tested and developed (hopefully.....) by the factory that developed the fuel injection systems and is best left alone. One specific area of development that any speed density system goes thru is testing of the fidelity of the MAP signal and hose lengths and hose volumes have a VERY definite effect on it and are frequently "tuned" by the factory for optimum MAP signal fidelity.

If you look at OEM fuel injection systems it would be very very rare to find any accessory or vacuum feed plumbed in parrallel with the MAP signal for just such a reason.

read the rest of the debate here http://www.fjrforum.com/forum//index.php?showtopic=16440&st=20

Darth lefty, DOE is used in many aspects of R&D and engineering fields, not just aero. BTW, what do you think DOE stands for? No hard feelings..... just wondering? You know how those Japanese are. Everything has got to be perfect:)
Design of experiment, Taguchi matrices, that sort of thing. Why, are you calling me out? :P My experience of such things so far is that they are pasted on as veneer over the actual engineering process, which is personality-driven when it's not accountant-driven. That might just mean my business is broken, which would not be a surprise.

Haha, not really calling you out just making sure we're talking about the same thing. You are right, not all fields practice DOE but it is a very useful tool that definitely cuts down on the time invested in some cases (but not all). Which accounting tends to like because of the old "time-value of money" thing. I had a friend who used it the design of washing machine components when he worked for whirlpool. He claims it saved the company............... ah who cares, I'll speak no more if this matter. We could start a new thread if its that important. I enjoyed the convo lefty. Cheers!

I tried this mod and have found a marked improvement in mirror vibrations at all speeds. Slow and fast. I highly recommend it.

I put it back to stock today. First thing I noticed, the bike was much smoother during warm up and it seemed to return to low idle quicker from a cold start. After I did the vacuum mod, RPMs varied a bit and it sputtered once and a while during warm up. I'd also have at least one big hesitation once under way about a minute into the ride with the vacuum hose teed into both TBs.

I've since installed a TBR can. When I first installed the TBR can I thought "this feels like the vacuum mod times a hundred". It's 78 degrees right now and I've plenty of power all around. I even had the front come up at 64mph over the tiniest bump in the road. There is no more "herky jerkiness" at lower speed/rpm that I noticed when the bike was stock. I think this is due to the TBR exhaust freeing things up and increasing the torque way down low in the RPM range.

I gotta say, I think the bike does feel more powerful back in stock trim. I always thought it was lacking power around 60mph, but tonight it was pulling hard. I'll know more after I ride it some more, and if we get another 90+ degree day. I believe the vacuum mod does smooth things out a tad at the lower end of the RPM range with the stock can, but perhaps it does so at the expense of a bit of power in certain circumstances. Nothing scientific of course.

I'm going to keep her stock, since there doesn't seem to be any advantage for me any more. I'm still thinking this mod might be a band aid for unbalanced throttle bodies. One day I'll sit down and balance the TBs and adjust the TPS.

If you really want to smooth things out and gain some extra grunt, get a new exhaust. It'll cost ya a lot more than $3 though. ;) As an added bonus you'll finally be able to hear your bike growl, and she'll drop an instant 10lbs.

This is an easy mod, easy to reverse too so there's no harm in trying it out.

:thumb:

Lukejt, which vacuum fittings did you have the T'd hose onto? Did you try it with a coupler hose and no T?

I had the left connection where it was originally, I placed the right tube where the rubber cap on the right TB was. Pretty sure there was a picture on the UK website that had this shown as config 2,where as config 1 was just a "jumper" hose between the two TBs. I definitely noticed a difference with the stock can after trying this mod. It did smooth things out around 2-4k rpm, I also think it may have helped reduce engine braking. Like I stated above, with the TBR can there really isn't a noticeable difference in smoothness or braking anymore, yet with the vacuum hose back to stock warm up was much smoother and also no more hesitation early on in the ride after a cold start up.

I'm actually the one who introduced it to the UK site in the Airbox Mod thread... I'll check my TB synch too and try it again without the coupler hose, now that my TPS is adjusted, ignition timing advanced 5 degrees, airbox mod, and removed sub-throttle plates with full Muzzy exhaust, and see what happens.

I rode at least 100 miles today, post vacuum mod removal. I must admit, there were a few times, no more than 3 or 4 where the bike did it's "herky jerky" bit that the hose mod seems to clear up. Could just be chain lash, but it's more pronounced, and I don't remember having it happen with the mod. Warm up is much better w/o the mod and there's no hesitation during the first few minutes of the ride. Power felt great all around today. With the mod as I had it setup I'd always get one big "hicup" after riding about a mile or so when I gave it throttle and the bike just about quits and then picks up power. This happened about once on every ride and went away once the engine was fully warmed up from riding a few minutes. Just stating my unscientific observations since you seem interested Invader.

Are you running a PC III now that you've got the airbox and sub-plates fixed? Or just the advanced timing? What octane do you run?

Thanks, Luke

I rode an SV1000 the other week, and let me tell you... the herky jerky on the V is much milder than on the SV. If the revs drop too low... that SV sure lets you know its displeasure!

(PS. That SV is just uncivilized! Scary fast!)

No PCIII... I already had a full Muzzy exhaust, removed PAIR valve and sub-throttle plates for my 1st ride on new Versys, and have always used 91 octane (95 RON). I later got a Piper Cross air filter, did the vacuum hose mod, and advanced the ignition timing 5 degrees when I tried 94 (98 RON). I then did the airbox mod, and adjusted the TPS, and it runs better and stronger than ever.
I should be able to check TB vacuum synch on Monday and test it out.
As one in the french forum puts it: Going back to stock after 1500 Kms (900 miles) with the TB's coupled, usable power obviously starts at a higher rpm and a bit more "violently". (The famous kick in the ass that some like more that I.) It's not faster nor slower, it just has a smoother and more linear operating range with the TB coupler hose.

I put it back to stock yesterday and could feel a noticable difference in snap on the way to work today. Thing is, I like it. It feels much quicker now.

I also checked my TPS and it is within range, and my TBs were synched perfectly. I've got 2000miles on her now, so kudos to the factory who set it up for doing it right. I assumed it would have been way off.

44t sprocket arrives today to address the short power band and all should be good.

I've got to say, the vacuum mod is no good in my books. To each his own.

B-

My TB vacuum synch was just a bit off. Left TB's vacuum bypass adjustment bypass was open about 3/4 turn, and now at ~7/8 turn. It seems to have helped low end a bit, and idle sounds better and even. Vacuum does increase on the left off 1300 rpm idle, up to over 4000 rpm as it equalizes itself again... I still prefer the clean low end response and tractability, and lack of jerkiness and bucking at part throttle variations with a 5/32" (3.83 mm) 6" long equalizer hose on (config 1).

I put mine back to stock a few days ago. It may be the power of suggestion from some of you guys, but I think it is peppier stock. It is definitely jerkier at low speeds/small throttle openings. Of course, I haven't checked my TB sync or TPS. I'm gonna run it like this for a bit...

Well I'll be damned. I did the vaccum mod last night and damn if it didn't smoth out the low end throttle response. I wish I knew exactally how this works. Anyone one know the details?

Not sure if related at all, but might have a similar effect to Yamaha's YICS that they hyped up in the 80's but seem to have discontinued. Involved linking throttle bodies together, goal was smoothness and efficiency I believe. Just a quick thought. The snappy throttle response at low rpm is common to alot of modern bikes probably in part due to having very light flywheels, lets engines rev a little more freely but can make em a little touchy at low rpm.

Hesitation and jerkiness is mostly due to a lean condition at lower rpm's. This can also be cured with a PCIII, but with some loss in fuel mileage.

Hesitation and jerkiness is mostly due to a lean condition at lower rpm's. This can also be cured with a PCIII, but with some loss in fuel mileage.

Thanks for pointing this out again for everyone on the site. I also mentioned elsewhere that the V runs a little lean at low rpm to meet emissions regs. as do most all modern bikes. Proper tuning of the stock bike would be of benefit. If a flywheel is too light it will lack initial inertia causing catchiness/chugginess/sensitive on-off throttle when rpm's drop towards idle speed on low speed manoeuvres. Heavier flywheels (to a point) improve drivability around town giving a smooth response at low rpm, but they do so at the expense of engine responsiveness and acceleration. Finding the right weight for drivability and a responsive feel is hard to do (ie. the manufacturer can't please everyone) but I think the V does very well in this regard with the set up by the factory design team. At a Formula 2000 Race Day I participated in the instructors took a few minutes just to review the fact that the formula cars we were using had no flywheel to speak of. Very different to shift and could be somewhat harsh, but smokin fast in terms of responsiveness and acceleration.

This is worth a read, it is about an FJR, but one of the posters designed fuel injection systems and he is urging another not to modify their IAP/MAP sensor plumbing. I think I will change mine back now after reading this info. I sent him a private message asking his opinion on the Versys mod, I will let you know if he comments.

One comment: It is NOT a good idea to tee a vaccuum source into the MAP signal line. I would never recommend nor condone that. It might not cause any problems on the surface but it is best to not take the chance. The plumbing of an additional vacuum "volume" into the line going to the MAP sensor can cause signal oscillations and signal errors in many speed density fuel injection systems. This situation with the MAP signal has been tested and developed (hopefully.....) by the factory that developed the fuel injection systems and is best left alone. One specific area of development that any speed density system goes thru is testing of the fidelity of the MAP signal and hose lengths and hose volumes have a VERY definite effect on it and are frequently "tuned" by the factory for optimum MAP signal fidelity.

If you look at OEM fuel injection systems it would be very very rare to find any accessory or vacuum feed plumbed in parrallel with the MAP signal for just such a reason.

read the rest of the debate here http://www.fjrforum.com/forum//index.php?showtopic=16440&st=20

Asked my mechanic about this mod and he essentially said the same thing. He's got over 35 years experience tuning and caring for both race and street bikes so I'll stick with his advice. BTW, great tips and advice by all.

I'll tell you guys, I really thought my V was lethargic and took FOREVER to pull through or from 60mph with this mod, tried all kinds of different gears and RPMs. Seems to blow right past 60 now. It's got more power stock. The mod will smooth things out though. Pluses and minuses. As soon as I read the above I went back to stock.

Configuration 1, like I have it does not have the IAT sensor hose on a T. There is only a 6" hose connecting both TB's vacuum fittings. I experience no power loss with this mod... Just a cleaner low end throttle response.

Hah! I finally got around to reading this thread. I reverted my vacuum hoses to stock a few weeks ago. I took the time to make a careful throttle body synchronization and the bike runs fine. I got tired of the sluggish take-off and hesitation with the re-routed hoses. As I have mentioned several times before, Kawasaki engineers probably know their bikes better than I. Maybe they had it right the first time. With the vacuum hoses, not throttle sync.

172 posts and now I can't remember what the stock setup was? I've probably lost the TB plugs things also. Can someone remind me how it was stock? Thanks.

/neil

I did this mod on the weekend but havent tested it properly yet , did feel smoother on the bottom just up the road and back .

I see a lot of you have gone back to stock , is any of you happier with the mod and would not change it back ?

Maybe the topic heading should be changed as some new owners may read the first few pages and do the change to just be dissapointed .

Im wondering if the mod doesn't richen up the system and therefore make the bottom end smooth but overfuel the mid to top , which will cause the lack of performance ?

172 posts and now I can't remember what the stock setup was? I've probably lost the TB plugs things also. Can someone remind me how it was stock? Thanks.

/neil

Viewed from above:

Vacuum hose from the MAP sensor connected to the left-most throttle body, far left vacuum port. Right most vacuum port on left throttle body, and the only vacuum port on the right throttle body are capped (used for synchronization.)

:D

Just an FYI:

I find it funny that invader posted what I did last Friday. I installed an Ivan's performance PAIR eliminator block-off plate kit, and while I had everything out of the way I pulled the secondary butterflies & "linked" the throttle body sync vacuum ports. Great minds think alike! I did this little trick on my Triumph SpeedMaster (carb'd,) and it didn't hurt a thing. Don't know if it make a big diff, but does seem to smooth out the part-throttle acceleration.

http://images41.fotki.com/v1346/photos/1/17642/6640253/IMG_1355-vi.jpg

http://images43.fotki.com/v1327/photos/1/17642/6640253/IMG_1347-vi.jpg

http://images39.fotki.com/v1349/photos/1/17642/6640253/IMG_1363-vi.jpg

http://images43.fotki.com/v1321/photos/1/17642/6640253/IMG_1364-vi.jpg

...I installed an Ivan's performance PAIR eliminator block-off plate kit, and while I had everything out of the way I pulled the secondary butterflies & "linked" the throttle body


Which kit did you buy from Ivan? I don't see one specifically listed.

Steve

Which kit did you buy from Ivan? I don't see one specifically listed.

Steve

:D:D

I was going to make a separate thread on this subject. I researched this until I was blue in the face, and finally took a chance that one of the existing kits would work. Success! It's the one for the newer ZX10's (actually, it'll fit the ZX14, and ZX636 as well.) Part # AK-KAW3.

http://www.indysuperbike.com/customer/product.php?productid=120748&cat=27172&page=1

Granted, you'll end up with a spare block-off plate, and and a few other unused items. I'm in the mind set to call Ivan and let him know this fits our bikes (and should fit the Ninja 650R, and newly US released ER6N as well.) He should start offering the kit with one plate for us... at a reduced cost too.

Works like a champ!

Jim

Did some further digging re this mod and the YICS that Yamaha used in the 80's. The Yamaha Induction Control System (YICS) was basically a vacuum balancing system in the intake manifold, connecting all 4 (in a 4 cyl bike) intakes together via small air passages (approx 1/8" diameter). Goal was smoothness down low and better efficiency. Do it yourselfers of the time advised trying rubber tubing and tee connectors as well as removing the rubber plugs from the balance tubes...boy this sounds familiar. It's affectionately known as the YICKS mod because it seemed to rob power and have hidden glitches. Yamaha dropped it later on. This info is just FYI. I just wanted to try and understand what this mod did and or does since it seemed so interesting. If it's such a great idea I think the factory design engineers would do this to all bikes. Seems like an interesting idea from 20-30 years ago that was tried by Yamaha (and do-it-yourselfers) and worked out to be less rather than more.

Yamaha's YICS actually consists of 2 seperate chambers, each connected by a hose to a port on each cylinder just behind the intake valve. As the piston moves down on the intake stroke, the cylinder fills with a fresh air/fuel charge. A vacuum is created in the YICS chamber at the same time. When the intake valve closes, part of the charge is drawn into the YICS. When the intake valve reopens, the mixture in the YICS shoots back out through an angled tube into the cylinder, mixing with and swirling the main intake charge. This system made it hard to synchonize the carbs...
http://www.xz550.com/YICS.html
Honda has the TB vacuum fittings coupler hose on PGM-FI twins.

http://cycles.evanfell.com/2008/02/1986-yamaha-tt350/
Hi Invader,
Someone said you're one of the go to guys on this forum and I was waiting for your reply. This mod really interests me and I'm just trying to understand it better.
Yes, I know that YICS involved a common gallery with small passages in it with the idea of swirling the charge, but there seems to be some similarities with the mod you describe.
Please check the above link, particularly the part which reads... The YICS was essentially a tube which internally connected all of the cylinder intake ports to balance vacuum pressure and eliminate symptoms of slightly unsynchronized carburetors and even out combustion...
Then please check this link to a video on youtube re synching TB's
http://ca.youtube.com/watch?v=UmLwyAPMBLI
Now the questions,
1. Some members that have tried this mod have had challenges. Could it be that all they need to do is synch the TB's and make sure they use your latest updated technique? I saw that someone checked their TB's and they were spot on, yet still had probs?
2. Someone felt they lost power at speed, Luke I think. Could it be that synching the TB's at 4000 rpm as suggested in the video would help this, maybe even get rid of some vibes at the 4000 to 5000 rpm range?
3. If Honda uses it on FI bike could it be that they have the ECU and maps set correctly to deal with it. Changing it on the V could be causing some sort of prob for the factory setup?
Look forward to your feedback, at your leisure of course.

It worked well on mine even before I adjusted the slightly off synch TB's. Some may have tried it differently... Nearly all who have tried it on the french forum like the mod and experience no loss in power.
TB synch on my V is balanced at 1300 rpm idle, goes off above idle, then balanced again at over 4000 rpm. Throttle opening, engine load and vacuum level are very different when cruising in top gear... I had to open the left crew from 3/4 to 7/8 turn open and it does run a bit better now. Idle sounds more even, and off throttle response is improved.
The IAP sensor is still on its left TB fitting. Just coupling the two TB's helps, perhaps by equalizing the inherent part-throttle low-rpm vacuum synch off-balance...

Viewed from above:

Vacuum hose from the MAP sensor connected to the left-most throttle body, far left vacuum port. Right most vacuum port on left throttle body, and the only vacuum port on the right throttle body are capped (used for synchronization.)

:D

Just an FYI:

I find it funny that invader posted what I did last Friday. I installed an Ivan's performance PAIR eliminator block-off plate kit, and while I had everything out of the way I pulled the secondary butterflies & "linked" the throttle body sync vacuum ports. Great minds think alike! I did this little trick on my Triumph SpeedMaster (carb'd,) and it didn't hurt a thing. Don't know if it make a big diff, but does seem to smooth out the part-throttle acceleration.



Looks good:thumb:
You can probably sell the other one to some guy on here. I made my own block-off plate out of 1/4" aluminum plate... You can remove the entire PAIR valve and connect its two wires together to avoid triggering the 'FI' light.

Yes sir, PAIR solenoid wires have been tied, soldered & heat shrink wrapped. Already sold the spare block-off plate as well. :D

Nice fabrication work there brother!

Take care,
Jim

Hi all,
Still trying to make sense of this mod and where probs could develop for people. It seems this mod basically makes up for slight imperfections in synching of the TB's by balancing pressure between the two. If this is true, why not just ensure the bike is properly tuned by performing a thorough and complete tune up?
Some useful links I came across while trying to make sense of this are as follows:
http://advwisdom.hogranch.com/Wisdom
http://www.geocities.com/sl_mille/synch.html
http://micapeak.com/TL1000s/faq/tps.html
The first link (once you get there click on TBSD at the bottom) I found interesting because he discusses how to modify a Twinmax for better results, and on page 9 discusses why and how to match vacuum under all throttle position rpm's and loads...different than matching TB's at idle or 3000 rpm or some other arbitrary number while on a centre stand.
By reading through the info on the links (and filtering through tons of other info at the same time) it seems that doing a proper TB synch precisely is critical in allowing the engine to run properly at low rpm and light throttle operation... which seems to be the goal of this mod.
Doing a proper and precise TB synch also seems to involve a lot more than just checking the vacuum balance.
Maybe this is a great mod, but in order for it to work well we would just have to check plugs, idle, TPS, air filter, throttle lever gap etc as discussed in the link re the TL and in the Versys service manual.
Invader, you've done alot of that with your bike (ie. TPS adjustment, idle adjustment, timing advance...) so maybe that's why it's worked out better for you than for some others. BTW Invader, I think you're a mechanical whiz for doing and posting all the stuff you have so far. But if some of the members are like me and can handle the basics ok, but defer to the experts or more experienced for trickier things, then maybe this mod requires a little more than just a 6" length of vacuum balancing hose in order for it to work well.
Cheers, and forgive my ramblings, just trying to make sense of it all.

I tried my bike today for the first time after doing the mod last weekend and all I can say is WOW . I am able to ride in dense traffic at any gear at any speed without the bike jerking . I have not felt any power loss , no backfiring , idling is the same .

Will test the V on top end later to see if any change , I did run it at 160 km/h this morning and it pulled as strong as always .

I wont change it back , also think it is going to help for the track day I am doing next wekend .

As a follow up to my above post, I finally checked out the ninja 650 and ER6-N site. They have a new posting re the vacuum hose mod which presents it much more clearly than what we have. They are also adamant that for trouble free results the TB's should be synched before the mod is done. Synching of the TB's appears to be more than a one step deal to do it properly, as per a review of the Versys service manual (which you can download at this link as well). As I mentioned above, this mod appears to compensate for TB's that are slightly out of synch (or maybe alot) by equalizing/balancing the pressure across the two TB's. The fact that this site suggests a thorough and complete synch job as per the service manual before doing the mod to yield better results would seem to support this notion. This also makes me wonder if some of the gains achieved are as a result of a proper tuning with only a subtle effect from the mod. As my dad always said, if you're gonna do sumpin, be thorough and do it right (the TB synch in this case).
Here's the link:
http://homepages.slingshot.co.nz/~shanetp/Index.html

Link to the homepage
Scroll down to Guides and General Info-at the bottom of this section click on the heading How Do I Do That And General Modifications
Then scroll down to the Vacuum Hose Mod and click Here

Glad to see the mod worked well Shawn. Maybe your TB's were synched well before you did the mod. Maybe some other members need to take this step.

Hope this helps anyone thinking of doing this mod.

Thanks Invader for posting this up in the first place. Very intersting.

BTW Shawn, which configuration did you use that worked so well? and good luck at the track!

The vacuum hose mod worked fine and offered as much benefit before and after advancing ignition timing, doing the airbox mod and synching the TB's... The Ninja 650 and ER6-N site picked up the idea from my thread, then I filled them in on it.

The vacuum hose mod worked fine and offered as much benefit before and after advancing ignition timing, doing the airbox mod and synching the TB's... The Ninja 650 and ER6-N site picked up the idea from my thread, then I filled them in on it.

I was wondering if that was the case for you re the effects before and after you did your other mods. BTW, I think the reference you gave re the YICS was the variation from the XZ550 vtwin Yamaha Vision. I used to own one in the early and mid 80's. It had one variation of the YICS system in which I don't believe the swirl chambers were linked, probably because it was a vtwin. Inline 4's had the YICS system with a common gallery across the top, and smaller passages/inlets to each cylinder. Guys who owned them sometimes dumped the YICS system and did what was called the Jason Mod...running one common tube with tees that sent separate tubes to link the vacuum ports...that's the part that I thought sounded similar to this mod. Various Yamaha forums discuss the Jason Mod as a do it yourself idea to try. The funny thing is, guys tried all different configurations of linking the vacuum ports. Some guys liked the effects and some guys hated it. Once again, the goal was improved tractability with some claiming increased torque. I have no idea who first started to do this mod, but it sounds like some Yamaha guys were doing something awfully similar back in the 80's. Some kind of irony there that this mod is still being discussed 20+ years later and no one seems to know why it works well for some and not for others. Bottom line is, evryone may end up having to try it for themselves just to see how it works out. But that might be a little like paying the dealer to see the next card... you may find out you shoulda stuck with what you had. As I said, thanks for posting all you do. You're a huge help to everyone.

...As I said, thanks for posting all you do. You're a huge help to everyone.


X2 :clap:

Red alert, I think that the aluminum plate you see is Invader's PAIR valve block plate. It's another mod that will keep an aftermarket exhaust from popping on decelleration. It seals the port that usually gets air from the PAIR valve to keep it from entering the exhaust.

For more info try a search on the forum for PAIR valve.

Sorry for hijacking, But you would be better off just blocking the actual unit itself. It's cheaper to use two rubber dowel ends instead of machining aluminum.

$.02

Sorry for hijacking, But you would be better off just blocking the actual unit itself. It's cheaper to use two rubber dowel ends instead of machining aluminum.

$.02

Where will you find your rubber dowel end, how much will you pay, will it seal properly, will it withstand the heat, and for how long?
My simple, solid, effective and beautiful aluminum plate cost me $0.00, but it's also available pre-made and meant for it.

Mind you, I have a 650R...

I got my dowel ends at OSH (or any hardware store.)
They cost me a total of $.35.
They work and hold up to the heat (what heat?).
I've had mine for over a year.

go to http://ninja650r.thefortycaliber.com and click on the "sub-throttle plate removal link."

You'll see what I did.

I just completed this mod today. I went all the way for it and took the bike apart down to taking the air box out. And when I reassmbled it, I went ahead and used some white foam tape at the mounting points for the various cowlings. Tested her out, still vibrates a bit, but it defenitly helped. As for the TB mod, I found that it just seemed to make the bottom end run cleaner and smoother. Defenitly liking the way it feels :)

I just completed this mod today. I went all the way for it and took the bike apart down to taking the air box out. And when I reassmbled it, I went ahead and used some white foam tape at the mounting points for the various cowlings. Tested her out, still vibrates a bit, but it defenitly helped. As for the TB mod, I found that it just seemed to make the bottom end run cleaner and smoother. Defenitly liking the way it feels :)


I find with my arrow headers I can run it down to 1500 RPM, and it pulls strong and smooth when I roll on the juice. They are like the vacuum mod perfected!

Has anyone done this with the Subthrottle plates removed?

this was a common mod on first gen FZ1's. lots of tubing and tees and linking the throttle bodies really helped smooth out the low end. Ivan's even made a kit for it if I remember correctly.

It wasn't that common and Ivan didn't ever make anything for it as it was simply some fuel hose and a couple of T's. IIRC, Bill Jinks (if any of you are the praying type, pray that he doesn't get a Versys) was the "originator" of the mod linking all 4 carbs with hose and some T's, but determined that linking pairs worked better. I can't remember if it was 1-3 and 2-4 or 1-4 and 2-3 that worked the best to alleviate vibes.

Thanks for the history lesson, Gorilla.

I did this mod on my V yesterday and the difference is noticeable - smoother at lower rpms. It will be a while before I can tell if it has an effect on mpgs. It took me more than an hour though as this was the first time I had the tank and airbox off - no problems but I just went slow.

I also modified my Vers vacuum hoses, because i noticed engine hickups after riding in, let's say, 4th gear with low throttle.... while gearing into 3rd and applying throttle, engine would sometimes make a hickup sound and would stutter a bit, and then it would accept throttle well. I talked with my mechanics and they thought it was all my imagination... after a few more guys came into the service with the same problem, they accepted that there may be a problem with the vacuum sync original setup. My Vers is going to be re-synced soon, and the vacuum mod still stays on, because it noticeably reduced engine hickups in slow revs and it reduced power drop when the hickpu occurs.

Thank you for the research and points.
Have not tried this engine mod yet but sure it will bring positive result.
Remember did the same (joining a tube between the throttle bodies) on my ex-bm boxer engine. It breathed better.

Thanks

Thank you, Invader.

Managed to do the mod you recommended without lifting the petrol tank.
Connected both tubes using a Y tube and the results are Supe...r:thumb:

Idling is smoother and noticed No loss of power. Now maybe more power in my head! The V just got better.

Best Regards.

Don't connect a Y or a T to the IAP sensor hose. Just use a 6" long 3 mm (1/8" ID) vacuum hose to couple both TB's vacuum synch fittings.

Hi invader,

Ok. understand what you mean.

To recap and to conform:
1. Leave the IAP alone as it was.
2. Connect both TB vacuum synch fittings.
3. Guess have to use the Y or T connector as the scottoiler is also connected to the left
TB vacuum synch fitting. Would this be okay?

Guess I saw a different picture then in the thread. Thanks for the heads up.

Hi invader,

Ok. understand what you mean.

To recap and to conform:
1. Leave the IAP alone as it was.
2. Connect both TB vacuum synch fittings.
3. Guess have to use the Y or T connector as the scottoiler is also connected to the left
TB vacuum synch fitting. Would this be okay?

Guess I saw a different picture then in the thread. Thanks for the heads up.

Yeah, you got it right...

Has anyone done this with the Subthrottle plates removed?

I did. See my previous posts..

Yeah, you got it right...

Did a short 100 mile spin.
Notice engine breaths better and slight increase in fuel economy.
Scottoiler seems to be working though connected with the 3mm hose with a Y tube.
IMHO, I think the twins have to pretty balanced in the first place before doing this mod. For me, I like it.

Invader, Thanks for the post.:)

I was intrigued at first, but will probably not make this mod. Let's see if I kind of understand what's going on. Replumbing essentially synchronizes the vacuum signal from the throttle bodies across the entire RPM range. This is an effective/somewhat effective bandaid for throttle bodies that aren't very well synched, or won't stay synched across the entire RPM range. It also increases the volume the vacuum signal comes from, which means the change in vacuum will be somewhat slower and more gradual: increasing the smoothness of the FI response to throttle changes at the expense of the rush and feel of more abrupt instantaneous response? (Kind of like having a heavier flywheel, except that it is completely different?)
I'm not even remotely an expert so feel free to point out any errors in my thought. I don't think that the "problems" on my Versys justify this mod, however it is an interesting possibility for my buzzy cantankerous 600 Bandit...

I did this mod, and initially thought it made a difference at low speeds, and off idle.

After using it for awhile, I began to notice a few things that made me think it wasn't doing what I thought it was.

I went back to the stock setup, I think stock is better, for me anyway.

I just did this mod over the weekend and it worked out great. Between the mod, new plugs and a clean air filter thing are back to factory smooth! In fact I think the mod makes it better than factory. Idles cold much better.:)

I wonder if this jerkiness issue only pertains to 49 state bikes?
I have a 2009 California bike (all stock) on which I commute daily in slow traffic, and the fueling is flawless and smooth with no hesitations, backfires, or jerkiness.
The throttle is also super smooth in the canyons. Overall it may be one of the smoothest bikes I've ridden especially going from off to on throttle.

I wonder if this jerkiness issue only pertains to 49 state bikes?

There is no jerkiness issue on the 49 state bikes. I have ridden several '08 and '09 and they were all just as smooth as you say yours is. If a particular bike has an issue, it may be due to poor TBS or other setup problem. Using the vacuum hose mod to "smooth" it out only masks the problem, it doesn't address the issue.

Gustavo

There is no jerkiness issue on the 49 state bikes. I have ridden several '08 and '09 and they were all just as smooth as you say yours is. If a particular bike has an issue, it may be due to poor TBS or other setup problem. Using the vacuum hose mod to "smooth" it out only masks the problem, it doesn't address the issue.

Gustavo

Anything that's set up for emissions control has a lot of compromises in the fuel map calibration. It's always a tug-of-war between emissions and driveability, and being that emissions have to be met, driveability isn't always optimum. Part of my job was concerned with auto emissions at Ford, and we always struggled with this very thing. When I bought the bike, I recognized immediately that driveability was just a bit marginal, and I wasn't very comfortable with it, especially the sensitivity and notchiness at small throttle openings. Using my old Ford driveability ratings, it was about a 3 out of a possible 5. Since installing and calibrating the PC V and wideband O2 sensor, I consider the driveability to be within a hair of a 5. It's a bit difficult to quantify, but overall, it's a lot sweeter and I don't notice the little annoyances I once did. Overall performance is noticeably better as well. This isn't an inexpensive way to go, but I'd recommend it to anyone.

What did the PC V and O2 sensor do to your mileage? Also where did you get/put the o2 sensor?

What did the PC V and O2 sensor do to your mileage? Also where did you get/put the o2 sensor?

The mileage is about the same, maybe a bit less. I haven't checked exactly. The O2 sensor is part of the Autotune add-on module that plugs in to the PC V.

I did this mod, and initially thought it made a difference at low speeds, and off idle.

After using it for awhile, I began to notice a few things that made me think it wasn't doing what I thought it was.

I went back to the stock setup, I think stock is better, for me anyway.

August, what are you saying? Doing what things? You're the first person who did it to give a thumbs down.

The mileage is about the same, maybe a bit less. I haven't checked exactly. The O2 sensor is part of the Autotune add-on module that plugs in to the PC V.

Where did you 'plumb' in your O2 sensor? Pics?

Ed :cheers:

Where did you 'plumb' in your O2 sensor? Pics?

Ed :cheers:

I have a Leo Vince SBK slip-on can, and it came with provision for one. It's on the left side just in front of the muffler, and angles up slightly. The Autotune setup comes with a fitting to weld in if you don't have one installed.

I want to try to explain the history of this mod.
As a lot of you know, this mod was thinked up by Mox, an Italian guy in Motoclub Tingavert Forum.

Mox began connecting left and right TB vacuum access fittings (he had this idea reading about PGM-FI Honda ignition system). This is the discussion (http://www.motoclub-tingavert.it/t229354s.html)

http://img191.imageshack.us/img191/8042/hosemod1.jpg

Versys became most smooth at low rpm and he noticed a little improvement of MPG.
When intake valves go close out, a bit of air/fuel mix stay out of the cylinder and it come back. The mix goes in the hose and it will be used in the next intake cycle. This is is Hose mod 1.

Then Mox seen that only left body is connected to IAP sensor. He put a T in the middle of the hose arc: born Hose mod 2 (here the discussion (http://www.motoclub-tingavert.it/t245846s.html)).
Smoothness was amplify: IAP sensor receive a balanced signal and give a more rich mixture at low rpms.

http://img193.imageshack.us/img193/4483/hosemod2a.jpg

In this solution, left flow was higher than right one because left bore for the hose to IAP sensor is larger than vacuum synchro bores, so he put the T close to right TB vacuum access fitting. Flows became more balanced.

http://img638.imageshack.us/img638/8052/hosemod2b.jpg

After a lot of tests, he selected this config.

http://img3.imageshack.us/img3/6813/hosemod2c.jpg

Right flow go directly to IAP sensor and original hose to IAP sensor is linked sideways. With this set up flows are very balanced, because the right-flow course is more direct and the left flow (wich has a largest bore) has a course less direct. For an optimal performance it is necessary a correct vacuum sync (between -0,37 and -0,38 bar). The hose between left and right sync bores must be smaller than the hose connected to IAP sensor (4 mm vs 6 mm).
Mox put another T near the left sync bore to easly connect a vacuum gauge.
Warning: it is necessary to wait above 100/150 miles to allow auto sets with new parameters.

very easy to do and great results ;) :thumb: :clap:

Bye

I remember seeing all those configuration evolutions, bur I opted for the first simple and highly efficient setup with a single 6" (15 cm long 1/8" [3.175 mm] ID) hose on both TB vacuum fittings... Do you run it with the last shown configuration? Doesn't the IAT sensor require vacuum pulse feedback from the left TB for proper fuel injection sequence, since there's no camshaft position sensor?

I found this discussion only few weeks ago.
At the moment I run the solution 1.
Maybe next mounth I will try last solution, when I'll remove tank and airbox to check sparkles and air filter. I think I'll cut air intake hose (what's the correct word?) like these
http://img218.imageshack.us/img218/8035/dsc00023ey2.th.jpg (http://img218.imageshack.us/img218/8035/dsc00023ey2.jpg).

Sorry, but I'm not sure I understood second part of your post (my english isn't so good):
IAP sensor don't needs left connection?

Bye

You mean the airbox inlets or snorkels... I fitted larger ones instead.
IAP hose senses vacuum pulses from left cylinder to determine proper fuel injector sequence, which is why it won't run properly with a single T fitting in between both TB's.

...
IAP hose senses vacuum pulses from left cylinder to determine proper fuel injector sequence, which is why it won't run properly with a single T fitting in between both TB's.

Ok. I'm not so well-trained in technic.
But the last solution adds to left signal the right signal coming from T. The hose connected to T don't replace left hose in IAP sensor.
Reading the discussion I understood that the last solution (wich balances left and right input from both cylinders) gives an altered signal to IAP sensor that modifies its output so it give a more rich air/fuel mixture at low RPMs.
This probably cause a little decrease of MPG.

Ι am thinking to do this mod, and to get rid of the Memjet(other thread)
What sollution is best?The first or the third?

Another question:
As i realize, this mod makes the mixture richer at the low end, but at the high end?
If leaves it at the stock setting, then its more than a must

Reading all the history of this mod, you understand that first config make your bike smoothness at low rpm, increase MPG and became easiest to go from low rpm to high rpms.
With third version of this mod, you will notice an amplification of effects of first version, because because IAP sensor is deceived by mod. At high rpms you can't feel big difference because improvement is very noticeable at low rpms with probably a little decrease of MPG.

It is very easy to do, you can try both solutions and then you can run what you preferred ;) .

Bye

Reading all the history of this mod, you understand that first config make your bike smoothness at low rpm, increase MPG and became easiest to go from low rpm to high rpms.
With third version of this mod, you will notice an amplification of effects of first version, because because IAP sensor is deceived by mod. At high rpms you can't feel big difference because improvement is very noticeable at low rpms with probably a little decrease of MPG.

It is very easy to do, you can try both solutions and then you can run what you preferred ;) .

Bye

So this mod makes the mixture richer at all rpm's?
If so, for my configuration it's useless, i can keep memjet for example

I don't know about the 3rd configuration, but there's no such concern with the 1st configuration. Smooth low-end throttle response, improved tractability and driveability, and fuel mileage seems a bit better.

I don't know about the 3rd configuration, but there's no such concern with the 1st configuration. Smooth low-end throttle response, improved tractability and driveability, and fuel mileage seems a bit better.

Invader, I'm lost. Just for the record, could you show me exactly what the above mentioned (1st config) mod is that you recommend ?

1st config is a single 6" (15 cm) long, 1/8" (3.175 mm) inner diameter vacuum hose on both TB vacuum fittings. Leave the inlet air pressure sensor hose on its specific outer fitting which has a smaller inner diameter... I used GoodYear automotive 1/8" vacuum hose which has a thicker wall that is less prone to collapsing under vacuum pressure, and I also upgraded the IAP sensor hose with it. :thumb:

http://img192.imageshack.us/img192/7090/standvac007.jpg (http://img192.imageshack.us/i/standvac007.jpg/)

Invader thanks, that's the way I'm headed once the riding season starts. :thumb:

Wait a minute
The picture above isn't the 3rd config?

Wait a minute
The picture above isn't the 3rd config?
It is 1st config.
http://img191.imageshack.us/img191/8042/hosemod1.jpg

and this is 3rd config
http://img3.imageshack.us/img3/6813/hosemod2c.jpg

In original italian topic (http://www.motoclub-tingavert.it/t245846s.html), they said that the mixture more rich is only under 3000 rpm and in on/off accelerator.

I did the mod today, the 1st option - just added a hose between the TB's. I won't speak about performance improvements or engine braking as I don't think it makes enough difference to really mention, but I will say that the bike does idle better now and it does seem to accelerate smoother from a stop.

I only have about 30 miles on the bike since the mod so I really haven't had a chance to really review it. If my opinion about the mod changes as the miles go on, I'll let you guys know.

- Benjamin

I did the mod today, the 1st option - just added a hose between the TB's. I won't speak about performance improvements or engine braking as I don't think it makes enough difference to really mention, but I will say that the bike does idle better now and it does seem to accelerate smoother from a stop.

I only have about 30 miles on the bike since the mod so I really haven't had a chance to really review it. If my opinion about the mod changes as the miles go on, I'll let you guys know.

- Benjamin

Benjamin, could you note any changes in MPG? thanks, Mark

Sure thing, but most of my driving is highway so I doubt there will be much change. I'll let you know though.

- Benjamin

Been using 1st config. for more than 6 months now.
IMO, idles better, less/minimum backfire and slight increase in mileage.
It takes off much better from stand still then before.

What I have connected to this 1st config. is the scottoiler's vacuum connection. No problems. Happy with the results.

This mod simply makes an improvement at low RPMs, the bike became more smooth and you have a little improvement of MPG. You can feel the difference in a road with a lot of curves, when you open and close accelerator.

Bye

helo alll ; y did tha PAIR vacum mot today too my V very inpresiv at low and midl,pulling wellie on second gear easy
but lost on top[over 8500]...sow back too normal

y hawe arrow heders,hurric exhaust,bmc filter.43 sproket

sory for my engls

helo alll ; y did tha PAIR vacum mot today too my V very inpresiv at low and midl,pulling wellie on second gear easy
but lost on top[over 8500]...sow back too normal

y hawe arrow heders,hurric exhaust,bmc filter.43 sproket

sory for my engls

The throttle body vacuum fittings' hose mod is not related to the PAIR valves on the valve cover... Power normally drops off at over 8500 rpm. Is there actually a difference in top speed?

this mod....bike not pulling sow hard in 2-5 gear after 8500rpm like befor..bike puling too 9500 in 5th imagin wat hapening in lower gear

normally drops power after 8500 ...but with arrow heders things change

I haven't noticed any top end power loss with vacuum hose mod config #1... It still pulls well up to rev-limiter at 10700 rpm in the first four gears. I already had a Muzzy header, custom Magnaflow silencer, removed sub-throttle plates, +5 degree ignition timing, airbox mod, sealed-off PAIR valve, 150/70 rear, 45T, etc.

maiby because of tha ignition timing eny wai since u mods warck well
u top speed...... pls

and thx,inveder

I just completed mod #1, got out last Friday. One thing I really noticed was when braking hard using the engine, I could smell a very rich fuel odder in the air. I am not sure if my mileage has dropped or not, I am going to leave it for one more try out with a full tank of new fuel. I assume this occurred before, but the increase in performance at low rpm has been due to the more vacuum on the IAP sensor, giving a a richer mixture. Engine braking seems to have the same effect, correct me if I am wrong.
Once I realized this, I started using the front and back brakes only, no engine braking.:feedback:

I did mod#1 today. Initial impression going around the block was: 1. Idle dropped around 200rpm; 2. Otherwise, no significant difference.

Will test more tomorrow if the rain stops long enough.

I tested mod config#1 a little more today. The idle is around 1100rpm after warmup; that's 200 rpm lower than before the change. I do notice the V is a little softer (smoother) taking off from a full stop. Otherwise, I could not find any difference. I'll leave the mod (#1) on for awhile and see how it does for a couple hundred miles. I may then switch back to check the difference again. Don't know if I should increase the idle rpm - everything feels ok at 1100 rpm.

I just completed mod #1, got out last Friday. One thing I really noticed was when braking hard using the engine, I could smell a very rich fuel odder in the air. I am not sure if my mileage has dropped or not, I am going to leave it for one more try out with a full tank of new fuel. I assume this occurred before, but the increase in performance at low rpm has been due to the more vacuum on the IAP sensor, giving a a richer mixture. Engine braking seems to have the same effect, correct me if I am wrong.
Once I realized this, I started using the front and back brakes only, no engine braking.:feedback:

You may test left and right vacuum: optimal synchronization is about at -0.38 bar in both cases.

Bye

Benjamin, could you note any changes in MPG? thanks, Mark
OK, I've had a chance to run a few tanks of gas through the V after the Mod (#1). I can't say that I've noticed any gas mileage changes. Most of the miles are on the highway between 60 and 80 depending on traffic so the bike hangs out between 5K and 6K on the tach.

I think this mod mostly affects lower RPM's, so I wasn't expecting to get any better gas mileage. It does take off a little smoother from a stop and seems to idle better, those are the only differences I've noticed after doing this mod.

- Benjamin

... those are the only differences I've noticed after doing this mod.

- Benjamin

These are the effects of this easy mod. more smoothness at low rpms and a little bit improvement of MPG, because V starts easier from a stop or a curve.

Happy rides!!

Thanks, that was what I was looking for. No bad news. This is next on my list.

OK, finally did the simple mod 1. Added the 6" piece between the TB's. I had some 7/64" windshield washer/ vacuum hose lying around so it was free. Did it with the tank on, a long skinny screw driver, my bare hands and some spit. Took five minutes to do (but 30 minutes to locate and remove the right hand vacuum cap that I dropped between the TB's). It is smoother at small throttle openings off idle for sure and during slow acceleration. I hadn't ridden the bike just prior to making the change for a comparo as it would have been hot.:thumb: