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Discussion Starter · #1 ·
Disclaimer

Following are the steps that have been followed to complete front end suspension modifications on my bike.

I am not a mechanic and these are not shop manual instructions.

If you choose to follow the steps on these pages, you do so AT YOUR OWN RISK.

I assume no liability for any damages, direct or otherwise, resulting from the use of this information.

If you are not comfortable or unfamiliar with this process, stop! Do not proceed and seek out a qualified technician to complete your suspension modifications.

Introduction

I have often heard suspension experts say that harshness is mainly caused by damping. In general, their findings have indicated that a controlled comfortable ride usually comprised linear springs that are stiffer than OEM along with milder compression damping and adequate rebound.

For many years, my quest for a more compliant touring suspension comprised the installation of progressive fork springs plus the use of lighter viscosity fork oils. Progressive springs are a compromise which allows low-speed comfort while preventing excessive bottoming. These springs are useful to ride on the street but not on a race track … but I like them because I’m a street only rider. :)

After having completed the above on my 2015 Versys 650, I decided that it was about time for me to stop procrastinating and to modify the front suspension damping assembly of my bike. I prefer a suspension that soaks up small bumps and pot holes on the road, but at the same time that is still firm enough to absorb the heavy ones. Along with enhanced riding comfort, I needed to avoid causing excessive front end dive during braking.

With the above in mind, I decided to revalve the damping (compression and rebound) in the right front fork of my 2015 Versys 650.

Note: This decision was inspired by this fork revalve thread for Gen 1 and Gen 2 Versys 650:


Fork revalve/ MK-1 / Others

Note: Before tackling a fork revalve, it is important to adjust the bike’s sag. Sag adjustments are well explained in Gustavo’s:

The Science and Black Magic of Suspension Setup

Important!

Before reading any further, download Race Tech’s PDF instruction document for the Versys 650.

Print the above downloaded instruction document, read it and also examine the diagrams closely. This should prove to be a very useful reference while going through the valving steps below.

Front End Disassembly

The front wheel, fender, calipers, forks, etc. need to be removed as explained in chapter 13-10 of the service manual.

Whenever fork legs are to be disassembled, it is important record each adjuster positions before disassembly. This makes it easier to return the front suspension to the current setting if need be.

If the left fork to be disassembled, the spring preload adjuster should be turned into the softest position.

Top Fork Plug Removal

For USD forks, I like to tape the top of each aluminum plug to protect them and then used a 30mm socket to loosen them.

Note: It is easier to loosen the fork plugs while they are still held by the steering stem rather than waiting to clamp them in a vice.





For the right fork, there is nothing special to watch out for other than the details shown in section 13-11 of the service manual.

Damping (Rebound & Compression) Cartridge Assembly Removal.

As explained in section 13-18 of the service manual, the bottom of the right fork was clamped into a vice (with soft grips). The bottom Allen bolt and copper washer were then removed as shown below.




This 6mm Allen key was used.



Note: I like to use an impact driver to loosen that bottom Allen bolt because, without using it, I have never had much success. When trying to remove these with a regular ratchet, etc., the loosened cartridge often tends to turn with the loosened Allen bolt that you are trying to remove. When that happens, it’s a royal PIA!

From the top of the fork tube, it was now possible to pull out the damping cartridge assembly.

Cartridge Assembly Bottom Cap Removal





The bottom cap shown in the above pic was easily removed by hand. Without the cap, the bottom of the compression valve assembly was now visible.





The removed Allen bolt was then screwed in a couple of turns into the compression valve assembly. I used a plastic mallet to tap the Allen bolt/compression valve assembly in far enough to be able to see and free the lock ring inside the cartridge tube.


Note: This Allen key/socket assembly was used to tap onto the screwed in Allen bolt:





As shown below, a small flathead screwdriver was used to move the lock ring sideways in order to be able to pull it out with long nose pliers.








The inside edge of my cartridge had rough edges, burrs, etc. which prevented me from easily removing the damping assembly. A round file was used to quickly deburr the inside end of the cartridge tube.




(continued)
 

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Discussion Starter · #2 ·
Gen3 Versys 650 Front Fork Valving - 2 of 5

The compression portion was used to gently tap out the compression assembly, etc.



Note that the rebound assembly is attached to the end of the guide rod while the compression assembly is by itself on the right side of the image.





Notice that the compression piston valve has an o-ring while the rebound one has a flat bushing. These two piston valves must not be interchanged.

Important!!! It is now a good idea to verify (with finger nail, etc.) how each of the check plates can be moved back and forth on and off its associated spring and cupped washer. Thus we know how these parts MUST be seated in order to function properly after having been reassembled.



Compression Shim Stack Disassembly

Cleanliness is critically important!
It is of utmost importance to work in a clean area. Any dust or dirt within the damping stacks will screw up the damping. I like to disassemble these parts inside a large plastic container on my work bench. Thus small parts have less chance of flying off and hiding from me. :)



The Allen bolt that retains the compression shim stack was unscrewed before laying each removed item down flat in order of disassembly.

After having unscrewed the Allen bolt, all pieces of my OEM compression stack assembly were laid out right to left in the same order as they had been assembled at Kawasaki.
Sorry … I should have laid them out left to right):



OEM Compression Stack Assembly - Top to Bottom:



In the above, the shims that could be changed to modify the damping are highlighted in yellow.

High Speed Damping vs Low Speed Damping

Damping is required in a suspension to control the speed of spring reactions. High vs low damping pertains to the speed of vertical up and down movements of the wheel. In other words high and low speed damping relate to controlling how fast the fork (or shock) is being either compressed (compression) or extended (rebound).

High speed damping comes into play when encountering sharp bumps (pot holes, curbs, etc.).

Low speed damping controls slow vertical wheel movements such as when going through slow dips or gullies, during braking at slow speeds, etc.

In our valving stacks, low speed damping will be controlled by low speed shims and high speed damping by high speed shims.

Note: It is important to realize that low speed shim adjustments will also have an effect on high speed damping.

Rebound Shim Stack Disassembly


In the following photo, to remove the rebound guide rod out of the cylinder tube, it was pushed out from left to right.



The rebound piston valve assembly on the end of the guide rod could now be disassembled.



If the end of the rebound valve shaft is peened, that peening must be gently filed off before removal of the nut. The end of the threads must also be deburred.

The nut was removed followed by the OEM rebound shim stack.

The pieces of my OEM rebound stack assembly shown below have been laid out left to right in the same order as they had been assembled on the guide shaft by Kawasaki :



OEM Rebound Stack Assembly - Top to Bottom:



Using the Race Tech Gold Valve approach without the Gold Valve (i.e.: using our modified OEM Showa piston valves)

When comparing a Showa piston to a Gold Valve piston, it is apparent that their large oil ports are of similar size.



Also notice that the Showa piston on the left is stepped in a similar fashion as the Gold Valve on the right. Shims will sit directly on top of these raised surfaces.

These Showa valves are therefore good candidates for modifications.

Chamfering the Piston Ports

To massage the pistons, I fastened each piston to a piece of plywood with a washer and screw before using a Dremel to open up the 3 ports on the stepped side.

Note: The ports on the raised portion where the shims sit were NOT chamfered.



My goal was NOT to enlarge the ports. It was to reduce turbulence by chamfering the port holes and removing sharp edges. I believe that this could enhance the quality of the flow (not necessarily the quantity). Think of how velocity stacks work on intake systems.

Before:






Getting There:



The above was done on both sides of each piston valve.

After:





(continued)
 

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Discussion Starter · #3 ·
Gen3 Versys 650 Front Fork Valving - 3 of 5

Bleed Holes:

Bleed holes are found on the Gen3 Showa valves.

Their purpose is to regulate (and soften) low speed damping. In low speed condition, the damping is controlled solely with the oil flowing through these bleed holes. In other words, the oil bypasses the shim stack. Note: The bleed hole also softens the high speed damping.

Note: I would guess that the Gen 1 & 2 Versys 650 damping valves might not have these bleed holes. If that is the case, this might be one of the reasons that the Gen 3 suspension feels more efficient.

I took a few pics of the pistons with a .57 mm piece of wire threaded through the bleed hole in each of the OEM Showa pistons.

For their Gold Valves, Race Tech mention that the standard (street) bleed hole size is a #55 (1.3 mm) diameter drill bit. For racing, to use a #60 (1.0 mm) drill bit.

I chose to leave the .57 mm bleed hole as is.

Bleed Hole in the Compression Valve:



Bleed Hole in the Rebound Valve:





Lapping the Piston Faces

Valving shims need smooth and flat surfaces to sit on. With this in mind, I lapped both faces of each piston over a plate glass with 400 grit followed by 800 grit sandpaper.



Lapped Piston Faces





Cleaning the Lapped Pistons

Mineral spirits have been used to remove dust, etc. from these piston valves. Other products such as contact cleaner, etc., could have been used. This is critical. Any dust or dirt within the damping stack assemblies could impede efficient damping.



Building the Compression Shim Stack

The fork compression chart in the Versys PDF instruction document that you have downloaded from Race Tech looks like this:



As can be seen above, each of the suggested shim stacks may comprise six 0.10 mm shims (one 9 mm diameter clamp shim followed by diameters 10, 11, 12, 13 and 15). These are constant (up to CH39).

17 mm diameter shims are to be added on top of the above .10 mm shims. For example one .15 X 17 mm shim could be chosen to obtain the softest setting possible. For much stiffer settings, as many as twelve .15 X 17 mm shims could be used.

The choice of shim stack largely depends on each individual’s particular weight, type of riding, skill level and personal preference.

Note that the main difference in the stacks listed in the above chart appears to be in the number of 0.15mm X 17mm shims used. The rest of the stack is almost always the same (from CH36 to CH39).

The objective is to create a valving stack that combines OEM pieces along with a chosen group of low and high speed shims. On the chart, I chose to start with CH36. Each item shown below is laid out left to right in the order that the CH36 stack was assembled.



CH36 – Top to Bottom:



Note: In the above, I needed to add 2 spacer washers to properly seat the shim stack. Otherwise the Allen bolt would have touched bottom in the valve body. This would result in a stack assembly that is too loose to function as it should.

Later on, I simply shortened that bolt to be able to use it without spacers as shown in the following CH33 example.


(continued)
 

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Discussion Starter · #4 ·
Gen3 Versys 650 Front Fork Valving - 4 of 5

Compression CH33 (left to right):



CH33 – Top to Bottom:



Cleaning the Shim Stack

All parts of the shim stack were washed in mineral spirits. Contact cleaner, etc., could have been used.
This is critical. Any dust or dirt within the damping stack assemblies could interfere with damping efficiency.



Compression Stack Assembly

My chosen compression shim stack was assembled in the order shown in the above CH36 and CH33 examples.

Note: On page 2 of your downloaded PDF instruction document, refer to steps 7, 8 and 9 and also to the Tuning Notes (information about damping, spring rates and oil levels).

As explained previously, it is critical that there is no binding between the check spring and the cupped washer.

A small amount of blue Loctite was applied on the Allen bolt before torquing it EXACTLY to 30 inch pounds (NOT foot-pounds!!!).

Caution: These threads can be easily damaged. This step is NOT to be taken lightly.



Building the Rebound Shim Stack

To build the rebound damping shim stack, the same logic as used previously for compression was followed. Refer to the following rebound chart in your downloaded Race Tech PDF instruction document.



As previously done for the compression valve stack, the chosen number of low speed .15 X 17 mm shims will depend on each individual’s preference. The number of high speed .10 mm shims remains constant.

Starting on the rebound damping rod, the following OEM parts need to be installed in this order: Cupped Washer + Check Spring, Check Plate, Rebound Piston. Low speed shims plus high speed shims are then installed followed by the base plate and the nut.

Caution: It’s very easy to misplace these small shims. I misplaced one of my .10 X 9 shims and therefore had to use a .20 X 9.5 shim to replace it. See below.

Note: I had started with RH19. This is the layout for RH16.

RH16 – Left to Right:



RH16 – Top to Bottom:



After having cleaned the complete rebound shim stack, etc. it was assembled on the rebound guide rod in the same order as shown above in the above RH16 example.

As explained previously, it was now very critical to make sure that there was no binding between the check spring and the cupped washer.

Note: On my rebound shim stack, I needed to add a spacer between the nut and the base plate because my new shim stack height was now lower than the original OEM one. Otherwise the rebound stack would not have been seated properly on the rebound guide shaft. For more shim stack seating information, in your downloaded PDF instruction document, see step 8 on page 2 and also steps A to C on page 3.



A small amount of blue Loctite was applied to the end threads on the guide rod before torquing the nut to exactly 30 inch pounds (NOT foot pounds!!!).

Caution: These threads can be easily damaged. This step must NOT be taken lightly.

Damping Cartridge Assembly



I used Race Tech Ultra Seal Grease to lubricate the compression o-ring and the rebound piston ring. In a pinch, fork oil could have done the job.

The rebound damping rod was pulled back into the cartridge. Then the compression assembly was now pushed far enough into the bottom of the cartridge to permit installing the retaining lock ring.

Finally the rebound damping rod was used to push the compression assembly back to the bottom of the cartridge. The bottom of the cartridge should now look like this:



With the addition of the bottom cap:



As explained in section 13-20 of the service manual, the newly built guide rod/cylinder unit assembly can now be inserted into the inner fork tube.

It is recommended to use a new Allen bolt copper gasket. I didn’t have a new copper gasket and there are no Kawasaki dealers in my area. I therefore purchased this one at a local Honda dealer.



A small amount of blue locking agent was applied to the threads of the Allen bolt.

The Allen bolt and gasket were installed to the bottom of the inner fork tube. The Allen bolt was then torqued to 20 N·m (2.0 kgf·m, 15 ft·lb).

(continued)
 

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Discussion Starter · #5 ·
Gen3 Versys 650 Front Fork Valving - 5 of 5

The Oil that I am Now Using:



In the past I have sometimes used ATF in my front forks. Most of the time I preferred to use Bel Ray fork oil.

After having read that many suspension tuners use Maxima fork oil because it is as “slippery” as any of the aftermarket fork oils such as Hyperpro, Race Tech, Ohlins, etc., I decided to try Maxima which proved to be a good choice.

Note: I chose to use light 5 weight oil because I wanted to let the valve shims do most of the damping. If the resulting compression damping on my bike had been too soft, I could have changed to a viscosity of 10, etc. Another choice could have been to add one or more slow speed shims to the compression valve assembly while keeping the same 5 weight oil.

Air Gaps On Top of Fork Oil Levels

Air gap is the space between the top of the oil level and the bottom of the fork cap.

For Gen3 Versys 650s, along with their higher rate springs, Race Tech suggests to try an air gap of 130 mm (without the spring) in the left fork and 70 mm in the right fork

https://racetech.com/ProductSearch/12/Kawasaki/Versys 650 ABS (KLE650)/2016

Since I’m using a Hyperpro fork spring which is of a higher spring rate than OEM, I decided to start with their suggested air gaps. I quickly realized that the results were exactly what I was looking for. I didn’t need to make more air gap adjustments. My suspension was now smooth and plush without excessive front end dives during emergency braking.

Had I been using the Versys OEM fork spring, I would have most probably started with air gaps which are between Race Tech’s suggestion and Kawasaki’s OEM specs (43 to 45 mm air gap in the right fork and 63 to 65 mm in the left fork). These measurements are to be taken from the top of the outer fork tube with the fork fully compressed.

Note: Fork oil viscosity combined with the shim stacks in our right fork controls the damping. The top air gap over the oil level has nothing to do with damping. When air is compressed, it acts like a spring. That is why it is said that air gaps that are too large might cause your forks to dive too fast. If the oil level is too high and that the air gap is now too small, it will affect the last bit of fork travel.

From Race Tech: “Oil levels can drastically alter bottoming resistance and only affects the last part of the travel (near bottoming). If you like the action, but the forks bottom too easily, raise your oil level by 10 mm (.4”).

It’s a personal call. The choice of air gap will depend on what fork spring rate is being used (OEM or aftermarket) and also your own preferences.

Different Strokes for Different Folks

Above was listed the sequence of steps that I have followed to revalve a Gen3 Versy 650 suspension. If you decide to follow these steps, make sure to customize them to satisfy your riding needs. This will depend on the types of roads ridden, your weight, riding style, etc. Thus the outcome will be result of combining your own damping valve specs with your own oil weight with your own air gap with your own spring rate, etc.

Look at your downloaded Race Tech document and see where you would like to start. Do you want a softer or stiffer compression? What about rebound? Do you want it faster or slower?

Note that this process required lots of testing and readjustments. I needed to disassemble the right fork more than four times before being satisfied with the results. During these changes, tests, etc. I also had to modify the rebound adjustments (how many turns out) over seven times.

I chose to start with compression CH36 and rebound rh19.

Since June 2018, my final choices have been: Compression CH31 (one .15 X 17 mm shim) and Rebound rh13 (two .15 X 17 mm shims). These shim stack settings suit my relaxed touring habits very well.

5 weight Maxima oil was used in the right fork with an air gap of 60 mm. The rebound adjuster has been set at 2 turns out.

Note: I kept the 15 weight oil in the left fork because it is not involved in damping. Its sole use is to lubricate the parts inside that fork. The air gap was set at 130 mm.

Because I’m using a Hyperpro Progressive fork spring, the preload on the left fork is set at zero.

The Static Sag (bike only) is 34 mm.

The Dynamic Sag (bike + rider) is 52 mm.

Where to Purchase Shims

Suspension Direct

6 mm ID shims are needed for our Versys 650. Note that the low speed shims are .15 mm thick while the high speed ones are .10 mm thick.

At the beginning of 2018, I ordered enough shims to be able to test different compression and rebound stacks. These were:

10 X .15 X 17 mm KLV61517
1 X .10 X 17 mm KLV61017
2 X .10 X 15 mm KLV61015
1 X .10 X 13 mm KLV61013
2 X .10 X 12 mm KLV61012
1 X .10 X 11 mm KLV61011
1 X .10 X 10 mm KLV61010
2 X .10 X 9 mm KLV61009

This was the detailed invoice:



If you look at their web site shim prices, you will realize that their shim prices are still the same today!

For anyone needing to order shims, I suggest calling SDI. I had ordered through their web site but nothing happened. After a while I decided to call them. Once I spoke to someone, the order was processed and shipped in a timely fashion.

Further Reading:

For anyone wishing to read additional information about motorcycle suspension tuning, following are a few references that I have particularly liked.

Race Tech’s Motorcycle Suspension Bible has been/is a very important reference.

Many excellent suspension tuning threads can be found the Triumph motocross forum:

IMHO Bruce Suspension knowledge base contains very good suspension information.

Conclusion

I have been riding with my revalved front fork for over 20,000 km and am quite satisfied with the results. I should not have procrastinated so long before getting this done.
 

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Nothing like a well documented How To do it right post, possibly a winter project. Now that I have the EBC brake pads, the dive is getting annoying.
 
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Discussion Starter · #9 ·
Now that I have the EBC brake pads, the dive is getting annoying.
In this case I would be tempted to add 1 cm of oil in each fork and then test for front dive. If still diving, add 1 more cm and then test, etc.


Before valving mine, with a Hyperpro spring, the air gap was 180 cm and everything was fine.


However with the valving, the dive was a bit too much. I gradually added oil a few times followed by testing until I hit the sweet spot: 130 cm as suggested by Race Tech.

Note: To do the above, I didn't open up the forks. After having my bike held up by my stand and ceiling lift, I removed the fork cap. Then lowered the front end a bit to let the cap come up away from the fork top before adding a measure amount of oil (the equivalent of 1 cm of oil).

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well.... I just finished the mod, and wow... I can not believe how much better it is. way so much better. this is really worth doing and total cost in parts is a bit over 30 bucks including the oil. I only did the right leg, using the suggested shim lineup in the CH33 list. the left leg still has the stock spring.

well of course, the bottom Allen bolt spun during the disassembly, even using the impact. I fooled with it for an hour at least but its not getting better. this isn't the first time I've had to do this so I know the fix is to drill off the head. BUT, that will never happen again on this bike. I pined it. with the compression valve body completely seated, I drilled a 1/8" hole through the cartridge assembly tube and into the valve body. I stopped before I hit the threaded part but got a hole almost 1/4" deep. I cut a piece of 1/8" steel rod to fit the hole & filed it to the contour. the bottom cap slides right over it & holds it captive. I have things that will grab the tube, so next fork seal change I won't need to worry, it will come out the easy way.

now, back to this mod.... do it. I took it out to a gravel road that has a mix of hard pack, moraines, has baby head boulders in places, etc. has some steep pitches that make washboard a couple inches deep too. I hit a pothole at speed (accidentally) & smoothed over that like its not there and the washboard is nothing... its so good it made my Ohlins rear shock feel rough
 
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