Valve Shimming Update.

Questions and comments about converting to beefier forks..
jafo
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Valve Shimming Update.

Post by jafo »

Well went out today with the recommended shim set-up to test it out. I ran right to the rocks first thing. It was still pretty stiff. I worked with the rebound and compression adjustments all day and finally got a halfway comfortable feel. I think I'm going to take the BV valves out tomorrow and take out some more shims.

Low speed hits were pretty good not bad, but thats with the comression adjustment dialed all the way out again. The rebound adjustment is at about 19 turns out from all the way closed.. I started the day with the compression adjustment 12 turns out and the rebound 14 turns out from closed. High speed hits were softer but still beat the snot out of my arms and wrists, not to mention my hands.

So now it's time to fidure out what shimms to take out. I was thinking about starting with the second shim stack. I don't think it'll take to much more. It's to the point now where it's not really that bad, but after a 2 to 3 hr. race, I won't be able to drive home. I'll have to pry my fingers from around the steering wheel if I do, they'll be cramped on....locked. I'm going to my other post and take a look at what shimms are left and try to figure out what one or ones to take out now.
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Post by jafo »

I just reviewed the info, and I think thats what I'll try next, taking the 24 and 19 shims out of the lower stack. The high speed hit's were where I was having most of the problem today. Bike ran great though. I had fun, enough fun i got a mild case of Monkey butt.

If this works out, I'm going to revalve the rear shock. I have my eye on a revlave kit on E-bay.
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Post by IdahoCharley »

I think you are on the right track - pulling the 24 and 19 below the cross over will soften both the low speed some and should allow you to close the compression BV clicker setting a few clicks. The real benefit will be felt in the high speed hits. Keep us updated.
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Post by skipro3 »

jafo,
I don't recall you discussing it, but be sure you don't have any induced fork tube stiction due to too tight of T clamp bolts. Tighten these bolts not more than 12 ft lbs. To check your forks for excessive stiction, stand next to your bike, holding it by the bars, and without using the front or rear brakes, bounce the front forks up and down. It should take very little effort. Then put your right foot on the left peg as you stand next to the bike on it's left side and bounce the bike up and down. Both the front forks and the rear shock should compress and rebound at the same time.
Good luck with the fork tuning!
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Post by Green Hornet »

Ski, I torqued the Upper bolts to 18 lbs & lower to 14.5 lbs. Same as KDX Manuel. Does the KX Manual require lighter torque??
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Post by KDXer »

That is too tight. My suspension tuner recommended 14 on both but I had stiction. I kept the tops 14 and backed the lowers off to 12.
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Post by Indawoods »

10-12 is about the norm for KX forks... at least on this conversion.
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Post by jafo »

I'll keep you all updated. That way if someone comes across a set of forks that has a double shim stack like mine, they'll know what to do to get it set-up for woods riding.

One thing I forgot to mention was roots. I hit plenty of them yesterday and it seemed to soak them up pretty well. as I said before, it's almost there. It just needs alittle more softness.

I also tried some downhill rock sections with plenty of baseball size rocks and larger. All loose on topp of the ground. It took the sections good but again just not quite there, just alittle more tweaking. Uphill was the same.

I tried some huge rock sections also where the rocks are very large and partly burried in the ground. The bike did much better, but with a few more shims out, I think it'll be just right.

The major difference I noticed on yesterdays ride was that there was'nt as much deflection. Hardly any really. But you could still feel the hit through the handle bars. Of coarse on real big rocks, your going to feel a hit hitting it straight on, but the deflection was much better (lack of) on the smaller stuff.

After this it'll be rear shock 101.
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Post by Green Hornet »

Okay-Trevor, did that work for ya. Stiction wise???
Same with you Vince??
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Post by Indawoods »

Mine are down to 10lbs.... hardly any stiction at all. They work real well. Any higher and they stick. Assembling the frontend in the right order and following the right procedure makes a major difference too.
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Post by Green Hornet »

I have to remount the front wheel, seems off, but runs straight. What is Stiction??
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Post by jafo »

Stiction is basicaly binding or resistance depending on which way you look at it. When your forks have "stiction, they are basicaly "hanging up". Not sliding in the forks easily because of one or both of two reasons. The clamps are torqued to toghitly, or when you install the front wheel, you get it mis alignedcausing the top of the forks out of line with the bottom of the forks causing binding. Stiction real bad can be seen in forks that when you hit the front break, they basicaly stick down or don't rebound back up all the way, they stick hense stiction. Other ways are more sudel, the forks just don't feel right. Or the action does'nt seem right or they just feel hard when riding. Which was some of the problem on my YZ forks.

I took Ski's advice and went out and double checked the alignment, and sure enough it was off just about a 1/16th of an inch. The forks feel alittle better now and glide much better. On my bike, the caliper side is held in place by the axle nut and the caliper side wheel spacer. Theres no where for the caliper side fork to go. So I lossened the oposite side axle clamp and rolled the bike hitting the front brake and pushing down about four times. Sure nuff, it was mis aligned, easy to do. It all looks good but it's not sometimes.

Just for your info G.H., the forks tubes has an inside and outside bushing. Meaning the inside bushing is the one driven into the lower part of the upper or outer tube just above the oil seal. Then theres the outside bushing. It's located almost at the very top of the inside or lower fork tube. when you tighten the fork clamp down to tight it will interfear with the operation of that top bushing that is located on the lower fork tube at the top of it. Inside bushing has the teflon on the inside diameter of the ring and the outside bushing has it on the outside. These keep everything lined up. Thats why bad bushings can also cause stiction. The inside ( lower fork tube) fork is missaligned to the outside (upper fork tube). The outside bushing glides on the inside of the upper fork tube, where the inside bushing glides on the outside of the inner tube or lower fork tube.

Theres probably a few other things that cause this but those are the most common.
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Post by jafo »

thanks for the reminder Ski, I'm going to have to ride the bike again before making the shim changes just to make sure. It glides much better, i just was'nt paying attention. :blink:
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Post by skipro3 »

Like it was said, stiction is binding; sticky friction.

Here's a way to measure how much stiction you have: With the bike off the stand, Press down on the forks and let them rebound very slowly. Measure a fixed point on the upper fork leg to the ground and jot it down. Now, raise the forks and lower them back down slowly. Measure the same point again to the ground. The difference is the amount of stiction you are having. By tightening and loosening the lower fork clamp pinch bolts, you can see a change in this stiction. In a perfect world, the forks would always return to the same measured point when at rest, wether they were rested from a compression stroke or a rebound stroke.
Stiction for the rear shock can be checked in the same manner.
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Post by Green Hornet »

I re-torqued to 10lbs. and found the one fork was about 1-2mm higher, tapped down and there close enough now.
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Post by jafo »

Well i dropped the bike to the ground and popped the BV's out and re shimmed them anyways. I took the 19mm and the 24 mm out of the lower stack. Kinda cushy. :razz: I went ahead and put the BV screws back in half way for a starting point. Bumped the rebound back up bout 4 turns also. Should be a good starting point. Kinda reminded me of the Ol' KDX forks when I got them done. Pretty plush. We'll see what a high speed impact feels like this weekend.

Yeh I know. I was going to try it out after the stiction problem was resolved before reshimming, but I had to try that neat idea of Charlies of laying the bike on it's side and popping the front wheel up in the air to get the BV out. Worked great. gotta get the front wheel preety far up to get the oil to run back to the top of the fork tubes. But i had both BV's done in about 30 min.


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Post by IdahoCharley »

Jafo - rebound should not change with removal of the 19 and 24 but you should be able to close the Compression clicker about 4 -5 clicks. My suggestion is to set your rebound during your next ride before final adjustment on the compression clicker. Less stiction is Very Good but mostly noticable in small washboard type terrian.
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Post by jafo »

I closed them up about 5 clicks. It stiffened them up alittle. But it's impossible to really tell until you hit something. I'll try adjusting the rebound first. Any good pointers on what I should be looking for when adjusting the rebound? I mean, what should I try on the bike to see where I'm at on the rebound? your basicaly looking to keep the front wheel planted in turns and stuff right? I just want to make sure i'm adjusting the right thing for the right situations. I understand the compression adjustment pretty well, so thats no problem.
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Post by canyncarvr »

Rebound for the fork will be the same idea as rebound for the shock.

The 'front wheel planted' part is indeed part of rebound...gotta keep in mind that there IS no rebound to worry about if your compression isn't right.

Keep the rebound fast enough to avoid packing (incrementally 'shorter' forks over stutter bumps). Otherwise, about as slow as you can get 'em.

That and understeer=too slow and oversteer=too fast. Again...considering you have the compression set up to ALLOW rebound to work.

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Post by IdahoCharley »

Jafo - I like to initially set the compression clicker fairly soft say 16-18 clicks open: I adjust the rebound fast (16-18 open) and then adjust the fork rebound by jumping single or spaced low whoops with the front wheel intentionally high: and slowing (increasing the rebound +) to control the fork's rebound upon landing. Essentially controlling the "bounce" back-up from the forks.

For me - low rises that could easily be rolled (no lip) in 2 gear I approach in third gear and apply throttle and weight transfer to pick-up the front end a couple of feet then I allow the front end to drop quickly (possibly even chop the throttle). Ideally the rear tire pretty much stays in contact with the roller. I increase the rebound + until the fork just rebounds just quickly enough after landing that the tire does not leave the ground a second time. This is usually ends up being within 1-3 clicks of my final rebound setting.

Then I focus on my LS compression clicker setting. Zip -ties/0-rings/dust rings or whatever your method of determining fork travel. I like separated smooth lip rollers that you can jump jump in 3rd or 4th gear with relatively flat landing areas (ditches) where you can bottom your suspension. (or a g-out) I try to land flat and bottom my forks and shock.

I look at the total travel indicated by the zip tie on the fork tube and somewhat go by my objective/subjective analysis of how I landed the jump and how the bike behaved. Normally increase the compression setting + on the fork until it feels good and hopefully balanced with the shock. I may make clicker changes in the shock setting to balance the front and rear.

Then I test ride the bike on a trail paying attention to turning, settling during braking, acceleration out of turns, etc to determine whether or not to make additional clicker changes. Make changes as deemed appropiate at the time and retest. If the forks are not performing to my liking I then make mental note on what the problem(s) seems to be; mentally work that problem on the way home. At home, I write down what I'am going to change on the forks (or shock) prior to the next ride. Usually within 2 or 3 or 4 rides I have an acceptable suspension for my riding style.
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P.S. I really don't know if you can make sense of my process, but the above method seems to works for me maybe it can work for you. I don't ride MX tracks and it seems all suspension tuning procedures are written like everyone rides SX or MX.

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