Backfire or popping sound in air box - Kawasaki Versys Forum
 
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post #1 of 17 (permalink) Old 05-15-2009, 09:27 PM Thread Starter
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Backfire or popping sound in air box

I have an 09 Versys with just about 1k on it now. Im noticing that I am getting a poping sound right off idle when I start to take off. It sounds lick a slight backfire or pop in the air box. Like I said it does this when you first twist the throttle off idle. Start the bike, let it warm up, put on my helmet etc hop on, click it down into first and apply some throttle and POP under the tank. Does not happen all the time and its usally right after start up. Anyone else have this issue???
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post #2 of 17 (permalink) Old 05-16-2009, 09:58 PM
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I have heard it usually when bike is cold and I am reving up at a stop light or something. How do you access the airbox?
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post #3 of 17 (permalink) Old 05-17-2009, 12:46 AM
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I'm getting the popping from the airbox normally during deceleration. I have 879 miles and added a custom slip on (cherry bomb equivalent) about 500 miles ago. The initial popping was coming from the pair valve which injects air into the exhaust to protect the cat converter. I disabled the pair valve, removed the subplates and the air box baffles in one shot. I even did the "vacuum hose mod" within the forum. With the baffles removed there was just too much ruckus from the air box. I reinstalled the baffles which quieted the noise but now I notice the popping (or maybe backfire) from just the air box. It does not matter if the bike is cold or hot. Never noticed when everything was stock but at that time I tried to keep her under 4k rpm. Come to think of it, if I decelerate from between 6 to 7k rpm in first I can sometimes reproduce it. Maybe the custom slip on is making the bike somewhat lean. Or maybe with the subplate removal I'm getting a little more or in the intake. But then again it could be the vacuum hose mod. I guess the main question is does your bike have any mods or is it completely stock? In my case maybe the subplate and vacuum hose mod does not work well together.
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post #4 of 17 (permalink) Old 05-17-2009, 04:43 AM
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I run with the vacuum hose mod (6" of 1/8" ID hose on TB's), airbox mod (larger baffles), removed sub-throttle plates and disabled PAIR valve with Muzzy header and custom silencer. The backfire which is in the exhaust (not in the airbox) is caused by lean air/fuel mixture, especially with low restriction exhaust, and is not worsened by stated mods. Adjusting the TPS up to spec virtually eliminated the light pop I had only when opening throttle a bit from a slight low-rev decceleration. Driveability and tractability is now also excellent, without any fuel management device.
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post #5 of 17 (permalink) Old 05-17-2009, 11:39 AM Thread Starter
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My bike is all stock with no mods. Im thinking about bringing it back to the dealer for them to check it out.
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post #6 of 17 (permalink) Old 05-18-2009, 07:04 AM
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Mine has done it once or twice over the past year or so. Seems the bike likes to idle when cold for a few moments before you give it any gas.
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post #7 of 17 (permalink) Old 05-18-2009, 08:32 AM
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My '08 with 1700 miles on it has these symptoms.

When cold and I am approaching a stop sign and I blip the throttle, some times it sounds like it backfires through the throttle body. It is almost exaclty like a backfire upthrough a carbuerator.

Once the backfire was so big, the engine stopped. This was when cold.

However, after 15 miles of a 20 mile commute home on interstate, I got off the highway and was approaching a red light, I went to blip the throttle and heard the backfire.

I think I should let the dealer take a look at it - my warranty expires next month.

ANy thoughts?
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post #8 of 17 (permalink) Old 05-18-2009, 01:15 PM
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If dead cold and I crack the throttle a little it may pop once in a blue moon. On decel you sometimes get a pop out the exhaust if you crack the throttle, that is a lean pop, hot exhaust, a little gas in the lean area of the RPM, etc. My guess, this is all caused by the bike being too lean from the factory for emissions, nothing a PCIII can't fix at the same time, I do not think there is any harm being done by an occasional fart.
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post #9 of 17 (permalink) Old 05-18-2009, 08:44 PM
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Quote:
Originally Posted by invader View Post
I run with the vacuum hose mod (6" of 1/8" ID hose on TB's), airbox mod (larger baffles), removed sub-throttle plates and disabled PAIR valve with Muzzy header and custom silencer. The backfire which is in the exhaust (not in the airbox) is caused by lean air/fuel mixture, especially with low restriction exhaust, and is not worsened by stated mods. Adjusting the TPS up to spec virtually eliminated the light pop I had only when opening throttle a bit from a slight low-rev decceleration. Driveability and tractability is now also excellent, without any fuel management device.
I looked in the service manual for adjustment of the TPS. Are you referring to page 3-42 "Main Throttle Sensor Removal/Adjustment? If so the book is not really helpful. It tells you to check resistance/voltage but if out of spec they want you to replace a part (the ecu). I see nothing about adjustment. The book also says that the sensor is factory adjusted and that the adjustment is very precise. Are you looking the in the service manual or is this a secret trick?

And one more question invader. Does removal of the sub throttle plates cause more air to enter the air box thus making the bike leaner especially with a custom slipon? Or is the amount of air the same but less restricted when entering the throttle bodies? Not to steal thunder from the OP but I'm also concerned about the occasional pop during decel but my pop started with the exhaust (yes, I plugged the pair valve) . So far I've read that the exhaust by itself does not require a power commander but when subplates are removed pc3 is required. Really trying to avoid another $300 dollar upgrade.

Last edited by cdmoore74; 05-18-2009 at 08:57 PM.
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post #10 of 17 (permalink) Old 05-18-2009, 11:48 PM
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It is funny that the section is called "Main Throttle Sensor Removal/Adjustment", yet mentions to not adjust it. It's just like the pilot fuel adjustment on carbs that are sealed off with a brass plug to discourage any attempt at adjusting the government imposed idle and low throttle opening lean air/fuel mixture for lowered emissions. The throttle sensor does have to be properly readjusted if removed or replaced...
I was able to verify that output voltage was a bit low, and adjusted it by rotating it counterclockwise to increase output voltage. This adds fuel and increases ignition timing advance from idle to mid throttle openings.
Before starting engine and with ignition on, check main throttle sensor input voltage and maximum output voltage. Input voltage can vary, which affects output voltage reading. Mine was either 4.76 V or 4.99 V (spec: 4.75~5.25 V). With input at 4.99 V, I set maximum throttle output to 4.22 V (spec: 4.2~4.4 V) to have idle position setting (after engine is warmed up with idle set at 1300 rpm) at 1.031 V, and within standard 1.005~1.035 V. This gave me a 4.04 V output at max throttle with an input of 4.76 V. I then just reduced the secondary throttle sensor to maximum counterclockwise position (it was already close), to reduce fast idle back to normal... I made my own adapter with some 0.032" solid wire and modified flat female connectors.

With removed subthrottle valve plates, admitted air is still controlled by the main throttle plates.
How well are your PAIR's air induction on the engine's valve cover, and airbox outlet sealed? I also removed the valve, and connected both valve control wires together to prevent trigerring an 'FI' trouble code.
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File Type: jpg tps13.jpg (104.0 KB, 694 views)
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Last edited by invader; 05-19-2009 at 02:18 AM.
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post #11 of 17 (permalink) Old 05-19-2009, 01:06 AM
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Quote:
Originally Posted by E46330i View Post
My bike is all stock with no mods. Im thinking about bringing it back to the dealer for them to check it out.
Mine is too and it does it as well. I am sure its "normal", Kawasaki has never built the perfect running bike in my opinion and I didnt expect the Versys to be perfect either.

ST1300, Versys, SV650S
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post #12 of 17 (permalink) Old 05-19-2009, 07:13 AM
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Quote:
Originally Posted by invader View Post
It is funny that the section is called "Main Throttle Sensor Removal/Adjustment", yet mentions to not adjust it. It's just like the pilot fuel adjustment on carbs that are sealed off with a brass plug to discourage any attempt at adjusting the government imposed idle and low throttle opening lean air/fuel mixture for lowered emissions. The throttle sensor does have to be properly readjusted if removed or replaced...
I was able to verify that output voltage was a bit low, and adjusted it by rotating it counterclockwise to increase output voltage. This adds fuel and increases ignition timing advance from idle to mid throttle openings.
Before starting engine and with ignition on, check main throttle sensor input voltage and maximum output voltage. Input voltage can vary, which affects output voltage reading. Mine was either 4.76 V or 4.99 V (spec: 4.75~5.25 V). With input at 4.99 V, I set maximum throttle output to 4.22 V (spec: 4.2~4.4 V) to have idle position setting (after engine is warmed up with idle set at 1300 rpm) at 1.031 V, and within standard 1.005~1.035 V. This gave me a 4.04 V output at max throttle with an input of 4.76 V. I then just reduced the secondary throttle sensor to maximum counterclockwise position (it was already close), to reduce fast idle back to normal... I made my own adapter with some 0.032" solid wire and modified flat female connectors.

With removed subthrottle valve plates, admitted air is still controlled by the main throttle plates.
How well are your PAIR's air induction on the engine's valve cover, and airbox outlet sealed? I also removed the valve, and connected both valve control wires together to prevent trigerring an 'FI' trouble code.

I used rubber caps and screw clamps sold through advance auto parts. It was a variety pack and I trimmed the larger cap as not to leave the cap protruding more than it has to. I noticed that some people were using aluminum adapter plates (opps, just noticed that your using the adapter plate) for this purpose but figured the vacuum can not be that strong to tear open thick rubber.
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post #13 of 17 (permalink) Old 05-19-2009, 08:19 AM
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I'm such a hack I just stuck a marrette into the pair hose, and a glue stick into the air box

2007 Versys Black, V35 Bags, H&B Bars, Skidmarx Hugger.Fender Ex., Avon Distanzia, Braided Lines, Hella 65W bulbs Arrow Can, DNA Air filter, GIVI tall screen (for winter), PCIII, Baldwin Saddle. **SOLD**

2011 KTM SM-T. Crash bars, E55 Top Box, Fender extender front and rear.
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post #14 of 17 (permalink) Old 05-19-2009, 06:46 PM
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I used rubber caps and screw clamps sold through advance auto parts. It was a variety pack and I trimmed the larger cap as not to leave the cap protruding more than it has to. I noticed that some people were using aluminum adapter plates (opps, just noticed that your using the adapter plate) for this purpose but figured the vacuum can not be that strong to tear open thick rubber.
So that rubber can take the heat and is snug in there? I made my own out of 1/4" aluminum plate...
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post #15 of 17 (permalink) Old 05-19-2009, 10:22 PM
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So that rubber can take the heat and is snug in there? I made my own out of 1/4" aluminum plate...

I checked the rubber just now and it's holding up fine so far. I bought this cap because it was advertised for use on heater cores if I remember correctly. I do feel a slight pulse when touching the top of it. I just don't think it will rip a hole into it but the aluminum plate would certainly do the job.

Is it just me or I'm I worried to much over the occasional pop from the air box? I can really get it to happen if I rev up to about 6k in first (showing off the exhaust ) and then let the revs drop when coming to a stop. When riding conservative the pop is rare.
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post #16 of 17 (permalink) Old 05-19-2009, 11:17 PM
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Originally Posted by cdmoore74 View Post
Is it just me or I'm I worried to much over the occasional pop from the air box? I can really get it to happen if I rev up to about 6k in first (showing off the exhaust ) and then let the revs drop when coming to a stop. When riding conservative the pop is rare.
Isn't it a backfire coming from the exhaust? You could try adjusting the throttle position sensor. You might want to try simply rotating the upper throttle sensor counterclockwise slightly and tune it "by ear" like invisabiker did after getting the idea from UK Versys forum. Measure its resistance from both outer connector prongs (ignition on/engine off) at maximum throttle opening (idle position can vary) first for a baseline... Rotate lower secondary throttle position sensor counterclockwise also to reduce cold fast-idle.

Airlock99 from UK forum: "Reconnect the plug, start the bike and set the idle about 2800-3000rpm. With your torx bit, break loose the screw holding the lower pot in place and gently rotate the pot back and forth, noting the effect on engine speed. When you find the sweet spot where the speed is the highest, lock the pot down and turn the bike off."

Last edited by invader; 05-19-2009 at 11:27 PM.
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post #17 of 17 (permalink) Old 05-21-2009, 10:30 PM
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Here's the scoop on the backfire. I decided to reverse the subplate mod and vacuum mod. I noticed that the popping on decel decreased but there was still a hint of pop; just not as bad as before. The down side is that the bike is less manageable in 1st gear at slow speeds. So I went back to config 1 for the vacuum mod and the bike is near perfect. I spent 20 minutes practicing slow speed maneuvering and I can now make slow turns in 1st and 2nd gear with smooth throttle control; no jerkiness, no grabbing for the clutch and very very little popping.

To sum it up:
1. Do the subplate mod if your looking for snappier take offs. Less restriction of air but with custom exhaust it will make the engine run a little more leaner (just an educated guess based on my results).
2. Do the vacuum mod for smoother throttle control at slow speeds.
3. Do not do both (at least in my case)
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