YZ 125 clutch slipping problem

I have a 99' yz 125 with some clutch issues. I put a new Hinson basket and Hinson pressure plate in it and changed the friction and steel plates along with the springs (Driven clutch kit). The only thing I haven't changed is the hub, It looks fine. I put it all back together exactly as the Clymer manual says. I also adjusted to clutch to obtain the right amount of free play. filled with 10-40 yamalube 4 stroke motorcycle oil and it still slips. Seems to run pretty good after it warms up a little though. I did notice that when i put the springs in they did not seat all the way down on the towers of the hub. when I took it apart the second time to see what was wrong i had to pull the springs off with channel locks. Shouldn't they come right out? Anyone have any suggestions? I think that because the springs are not seating all the way down and are binding on the towers that when I torque them down they are applying pressure to the pressure plate which is taking pressure off the friction plates and allowing the clutch to slip. Does this sound logical or am i way off? Thanks

Edited by joshnobogies
added to the question

Have you tried an extra steel plate?

I checked all the plates with vener calipers and they checked out within the specs. Adding another friction/steel combination puts the total thickness out of spec range

Ok but if the aftermarket basket and pressure plate are different from the OEM setup all your specs are off anyway. So what harm will be done if you try on extra plate?

Good point. I will try it. What about the springs? shouldn't they seat all the way down on the hub towers? this is the first time i have messed with a clutch. I think there is enough room to fit another fiber/steel combo on there. if i can only add one. which one should i add? Steel or fiber? I know i need to start with a fiber and end with a fiber but if i have to add one extra where should i add it and which one should it be?


Hello there

I only worked with OEM clutch on my bike but I know that 1 or 2 tenth of a mm can make a difference between slipping and not slipping. I read that someone advised one extra steel plate which makes sense to see if it is because of the length of the push rod assembly.



anyone else have any ideas or references as to whether or not (and where) a steel plate or fiber plate should be added? as of right now i plan to remove the last fiber plate, add a steel plate then put the last fiber on so i end fiber, steel, steel, fiber, pressure plate.

So far I remember you take the forth steel plate and add another steel plate to it. Doubling one steel plate.

Sounds good to me, I'll try it and post the result. Thanks again

Had time to work on the bike this weekend. Extra steel plate worked great. Thanks again for the help.

Very nice, will this work on a stock setup? I am having slippage issues after a new Tusk HD kit. The free play is adjusted up, but it still slips until it is warm.

Check to make sure the two washers are in the correct order... the thickest one goes in first followed by the basket then the other washer, also be sure to check the push rod and be sure that its not worn.

I put an the extra steel plate in and have been out a few times on the track. I'm a beginner so i'm still "trying" to go fast. It seems to be holding up pretty good so far.

Adding that steel plate is curing the symptom, not the problem. I would take it back down and make sure that all of the parts are in spec, that you have the washers in the proper order, and that the pushrod is in good shape.

Masking symptoms with band aids usually leads to more problems.

not sure if the specs are any good anymore because of the aftermarket basket and pressure plate. I checked the friction plates with veneer calipers and they all checked out within specs. Push rod is in good shape also. The only thing I am not 100% sure of is the washers.

Lets say they are in the correct order (with the thicker of the two going on first), what would you suggest then?

Adding that steel plate is curing the symptom, not the problem.

I don't get it, if the clutch slipps and the extra steel plate corrects it it the problem is solved. The symptom was the slipping clutch.



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