REMOVING FORK SHIMS - any down side?

[KDX220 Rider]

There have been several threads in the past on removing two of the shims from the compression stack on the bottom of the fork. The results that people have posted have all been extremely positive. I didn't see any posts where anyone had any issues with the change. I have not done the mod yet, but will likely try it. I got to thinking, "if this improves the fork action that much, why didn't Kawasaki send the forks out this way?" It's obvious they never spent a lot of R&D time or money on the KDX line, but this seems so simple a change. In fact, it would have been cheaper for them to leave out the two shims in the first place. Am I missing something?

Also, there was discussion about posting pixs of the procedure, but I never could find any link. Did this ever get posted, or can someone post them now? (Flop2 was one person that mentioned this, but I was unable to send him an email.)

Thanks,
KDX220 Rider

 

[KDX220 Rider]

Anyone have problems with the mod?

Bump. Any feedback would be appreciated.

Thanks,
KDX220 Rider

 

[exbike]

I think Kawasaki's original design theory included having the KDX 200/220 lightly sprung up front with relatively heavy compression damping to compensate. I think more modern suspension thinking includes spring rates that are much higher than OEM KDX rates. If you pull the shims without getting springs that are appropriate for your weight, you will be undersprung and underdamped (compression-wise) for that spring rate. A good combination is to install rider-weight appropriate springs and then remove two compression shims.

I'm a heavy-ish guy (195 nekkid) and I installed .43 springs and removed two compression shims. This modification was a distinct improvement in my mind. YMMV. Of course I fully serviced the forks while they were apart, replaced all seals and bushings and loaded fresh fork oil to the appropriate level.

Good luck.

-Matt

 

[KDX220 Rider]

exbike,
Thanks for your comments and they seem to make sense. I'm about 160 w/o gear and have been running Race Tech 0.38 springs for a several years. They seem to work okay for my weight, I suppose. I've never been that thrilled about the fork action but don't have the $$ to revalve. I've been away from DRN for several years and just recently came across the old tread. This seems to be a good compromise.

If I understood you correctly, you took the forks completely apart so you didn't use the impact wrench trick while the forks were together. I don't have an impact wrench but can probably get access to one. I do have some concerns about the bottom cap not coming loose and the internals spinning. (The bottom of my forks have a few dings so I'm not sure if it's enough to keep the cap from easily coming loose. They're not dinged real bad, I'm just paranoid.) Do you have an official "internal fork holding tool" or did you make one? I haven't checked yet to see if anyone has details on making a homemade tool. I'm thinking someone has made one.

Thanks,
KDX220 Rider

 

[Yamadad]

The only down side is that you have to be veeerrrrry careful in removing the nut that holds the shim stack in place, because its staked and the aluminum housing will break very easily.

 

[seb33]

Just go on justkdx site and you will find a drawing to make the tool you need.

 

[glad2ride]

Buy the tool from www.frpoffroad.com. It works great!

 

[robl]

Primary down side: poor rebound
It's an easy job if you have the following tools:
impact wrentch
14mm allen socket - got mine at an industrial tool supply store
dremel tool, or bench grinder
tie-down straps

Here’s what I did:
1. I compressed my fork legs with a tie-down strap
2. Loosened the valve body with the impact wrench, but didn’t remove it
3. Removed the tie-down strap to release the forks, and turned them upside-down.
4. Removed valve body
5. Ground off the “stacked” part of the nut so it could be removed.
6. Removed 2 shims, and reassembled. Loctite might be a good idea on the shim nut.
7. Don’t use the impact to tighten it up. I just used a torque wrench and I think 35 ft-lbs was all I could get it to.

I have lots of trail miles on it since, so here are my thoughts.

On smooth easy trails, the difference isn't very noticeable. However, it is a significant improvement over the stock forks on difficult trails as long as you have the correct spring rate. I ride rough / rocky single track in North Idaho and found the bike to deflect quite a bit less. The high speed compression is better, but now the rebound is more than you will want.

Overall, the KDX forks still are terrible. Removing two shims makes them suck a lot less, but they’re still terrible when you push the bike hard on difficult terrain. Having them reworked with racetech components is the best thing that can be done for them, but that’s $450 or so. I plan to switch to KX forks in the future.

 

[KDX220 Rider]

Robl,
Thanks for the feedback on the trail manners. This is the first mention I've heard on the rebound change. Did the rebound slow down or speed up? I'm not sure I understand why, since this change is on the compression stack. ??? Can't this be offset with a oil level change?

I have a couple of questions on your instruction list.

On step #1 with the tiedowns, I'm thinking you put the axle through the axle clamp and then put a hook on each side of the axle, with the strap around the top of the fork. Is this correct?

On step #6, I'm assuming that the loctite takes the place of the factory staked nut. Is this correct?

Thanks again for your feedback,
KDX220 Rider

 

[robl]

Well, these forks are pretty simple. With these 2 shims removed, the forks compress and rebound quite a bit easier. It's a trade off I guess. Overall it is an improvement though, so I wouldn't worry about it. You may be able to further fine tune things with the oil level, or possible a 7 wt oil. I've never tried either.

On the tie down strap, yes I did put the axel back into the clamp on that side.

On the loctite, it could be a little insurance that the nut won't come loose. I actually didn't do this and I'm thinking I should have.

Good luck with it! I should have taken pictures. I didn't even think about it at the time.

Rob

 

[matt-itude]

I didnt notice a rebound change when I did mine. Like previously stated it shouldnt change (different stack of shims)the rebound. For free it is a huge improvement over stock. Make shure and get the right springs to go with it if you havent already. I weigh 225 and used 44 springs and mixed half and half 5w & 7w oils. I have lost weight since (about 20 lbs) and wish the springs were a little lighter.dont remember what height I set the oil at. For the price try it then decide if you want to spend more. It is well worth the little bit of time it takes.

 

[glad2ride]

The rebound valving is at the end of the damper rod, so something else caused your rebound change. You may want to check your damper rod bushings, rebound piston bands, damper rod surface, cartridge surface, etc.

YES!! You need some Loc-tite on it! I think the post is actually peened over the nut and not the nut being staked.

 

[john stu]

any down side to removing the forks?

 

[seb33]

No it is really easy to remove with the proper tool I did mine (change the oil and remove the shim in about 3 hours) one thing to consider is to change the o-ring on the valve cartridge one of mine was broke when I remove the cartridge.

 

[steve.emma]

on my 99' 220 i did the whole fork mod thing including using xr400 springs and removing 2 of the shims etc.. this worked great for me and made a big difference over stock, but i thing the springs do more than the revalve by itself.
doing this mod will not affect the rebound in any way. if you want to change rebound you can use a thicker oil (although this will slow the compression down as well) or you can do what i did and add 1 of the spare compression shims to the rebound stack using the same method as before. this is easy to do and helped slow the rebound down and reduced some of the arm pump on fast rutted trails.