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super stiff yz forks after rebuild


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the fork on my 2002 yz125 were getting really stiff and harsh. so i got the pivot works seal and bushing kit and rebuilt them. used racetech ultra slick lt wt oil. i put a stiffer spring on the rear but didnt have the $$ for stiffer fork springs, (has .41kg/mm springs) so i put in 3 racetech 5mm fork spring preload washers on each side. they didnt feel that stiff when i was done and pushed down on them but now that they are on the bike they are almost immoveable!! cant barely push down on them an inch. i reloosened the bottom axle blocks and made sure they wernt out of line but they are soooo stiff. but they were that way before too. so what gives? i didnt see anything inside the fork that was wrong. clickers have no effect on changing the stiffness. i think something may be bent and binding. any opinions?

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hard to give a remote diagnosis

but if you are sure the fork isn't bound, check the torque of the tripple clamps, esp. the lower one.

check the sag, might be too little

btw, additional 15mm preload is ridiculous much

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btw, additional 15mm preload is ridiculous much

Ya, X 2 on that. Personally I never cared for the Pivot Works seals & bushs as the quality control wasn't great. I've seen them have lots of stiction.

That being said how did you check the R/S fork for binding, by just loosening the bolts and pushing on the forks? If the end of the axle is mushroomed (from hitting it with a metal hammer) then it will never set itself right.

This is how I do it..........

1.Install both forks and set fork height using calipers or a ruler. It is important that fork height be exactly the same for both sides. Tighten pinch bolts to the proper specs (Top: 18 Ft-Lbs | Lower: 15 Ft-Lbs).

2.Before installing axle make sure the end of it (and the edge of axle hole) has not been "mushroomed" from hitting it with a metal hammer. If theres any lip it must be ground off or fork will bind.

3.Install the axle (use rubber or plastic hammer only) and tighten the axle nut to proper spec. If the axle turns while tightening, tighten one right side axle pinch bolt to hold axle in place.

4.Tighten both left side axle pinch bolts to spec.

5.With the left side axle pinch bolts and axle nut tightened, loosen the right side axle pinch bolts. Take a small flat head screwdriver and carefully tap it into the slot between the two right side axle pinch bolts. This will enlarge the axle hole. You will then be able to grab the bottom of the right side fork tube and push it in and pull it out freely. You will be able to see the fork settle naturally into position on the axle without binding.

6.Remove the screwdriver and tighten the right side axle pinch bolts to spec.

If you're wondering if your forks are currently bound up, put your bike on a stand and start this procedure at Step 4.

If all thats good then I would take those spacers out (would do that anyways) and try OEM bushings & seals or those new MX Teck seals and see how it feels.

You did set the oil level with the forks bottomed, springs out and then make sure to adjust for the oil trapped between the tube & leg right?

doc

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well that sounds pretty technical. I take my kayaba forked bikes and before I tighten up the pinch bolts I bounce the front end up and down a couple times then use 1/4 inch torque wrench and tighten the pinch bolts to spec. When I don't do this front end feels almost solid

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well that sounds pretty technical. I take my kayaba forked bikes and before I tighten up the pinch bolts I bounce the front end up and down a couple times then use 1/4 inch torque wrench and tighten the pinch bolts to spec. When I don't do this front end feels almost solid

Well actually its not. Doing it your way in all reality, you are just assuming that the R/S fork is set right. Doing it my way lets you actually see that its right and not just "assume" it is.

doc

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The end of axle was mushroomed, and i did grind off the mushrooming. maybe there is a burr in the axle block. i think i will take out 2 spacers either side. i torqued clamp bolts to spec. thing is they were super stiff before, thats why i rebuilt them. set oil level to 110mm spring out compressed. im going to try your centering method after i take the 2 spacers out.

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looks like i will have to redo the forks again, as i dont like the opinions i got on the pivot works bushings, the old ones looked fine. no wear and all the teflon still in good shape. i think i will take the caps off, remove springs and spacers and trade out the bushings and check seals for stiction. then re set oil level and put back together and use the shock docs method to tighten the R axle block. fun fun. ­čśĆ

thanks let u know how it works out.

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The end of axle was mushroomed, and i did grind off the mushrooming.

thing is they were super stiff before, thats why i rebuilt them. .

Well if the axle was mushroom before then thats why they were stiff. Do check the inside lip of the axle hole tho as after hammering the axle in enough to mushroom it over time you can easily get a burr from the shoulder on the R/S of the axle as that bigger part tries to go thru the block.

doc

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yes the cartridges moved smoothly and there was no signs of wear on the shafts or knicks.

Bad communication on my part, what I meant was with the cartridge removed (on rebuild) did the outer tubes move in and out smoothly?

Another thing is did you ride it yet? If you didn't put enough oil near the seals and bushings when rebuilding it it might be a little dry and could take a little time for the oil to migrate to the seals and bushings.

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That fork is a cylinder valve fork that has its bottom out system just under the fork cap. I hope you have fitted the preload washers at the bottom and not the top as enormous damage can result if the washers mis-align. As previously mentioned...remove the spacers as 15mm is too much. Talk to Shockdoc about addressing the cylinder valve. This is a major problem with this fork design and the primary cause of harshness and bottoming.

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Took out two preload spacers per side just one now each side. Checked the axle alignment per shockdoc. Was ok. The aclewas mushroomed when I got it ad I fixed that the first time I put a frt tire on, not just now. Rode the bike around for a bit and worked the suspension by popping a couple wheelie and stoppies and now seems a lot better. Going to go her a rip tm and well see how it goes.

Also when I took out the spacers the rubber cones under the caps were broken in peices. Big peices, like 3, guess they were old. Got some on order now tho. What do those do? And what damage could happen from the spacers at the top? I have them at bottom anyways.

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rode the bike on sunday, actually my dad did since its his bike lol. he didnt say anything about the forks being stiff. we softened the shock a bit and set the sag. it was a little tight. i took it for a spin and its as good as new again! ­čśĆ just have to replace those rubber cones under the caps now.

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Also when I took out the spacers the rubber cones under the caps were broken in peices. Big peices, like 3, guess they were old. .

Those are your bottoming bumpers and if they are all broke up then you can bet that lots of smaller pieces are circulating through the oil and getting caught in the base and mv shims and pistons. Gonna need to completely clean them out thoroghly when you get the new ones.

Also listen to what Terry said about the CV as he had them dialed with an all new piece that made the forks work sweet.

doc

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i dont think any peices got in the oil as i never rode it before i noticed they were broken. they were old looking when i rebuilt forks, but ok. then i put forks on bike and they seemed super stiff just pushing down on them. so i pulled the bars off and pulled off the caps and took out those rubbers and they were broken into 3 large peices on one side and 2 peices on the other. left them out and put forks back together. they should be in this week and i will put the new ones in.

you are talking about the base valves right? cv? the forks were revalved by factory connection ages ago. are you talking about those base valves that race tech sells? they seem to be working fine now.

i think it was just dry seals/bushings. maybe a little out of alignment axle too.

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  • 2 weeks later...

no offense doc but i think you are talking about the newer sss forks. the ones i have on the 2002 yz125 are the older style kayaba open cartridge 46mm forks. they have no valve at the "top of cart" unless you mean the bottom as the top, thinking of it like a newer cartridge fork.

its ok now, works good and my dad likes it. thats all that matters to me. replaced those bottom out rubbers, its all good now.

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