03 YZ450 Clutch Mod

Hopefully someone can help me on this. I want to eliminate the clutch chatter issue that I have been having on my 450 for years and have found that the fix is replacing some of the components with the 02 wr426 parts. My question is that in the Dr. D handbook for mods for the 450 they say to install the wr 426 fiber plate, then the base ring, then the waiver spring followed by the rest of the clutch pack ending up with one extra fiber that you would not use which would mean the pressure plate would be up against a metal plate, is this right? The order of the 3 wr 426 parts does not match the order shown on the wr 426 break down. Also ending up with the last plate being a metal plate does not sound correct, can someone please help clarify? Thank you.

There should actually be no reason for an '03 to chatter, but some of them did. If the basket is grooved, the basket cushions in the gear assembly have slack in them, the boss is grooved, or the friction plates have hardened, all those things will contribute.

Nonetheless, the parts and procedure is discussed here in the info for the '01 clutch mod for 2000 model 426's:


The parts you need are:

1 of JG-16321-00-00 PLATE, FRICTION (item 12) **

1 of JG-16383-00-00 SPRING, CLUTCH BOSS (item 13) **

1 of JG-16384-00-00 PLATE, SEAT (item 14) **

To install, remove the whole clutch pack, place the "seat plate" (the flat ring) on the clutch boss (hub), followed by the "boss spring", the "dished" or conical spring plate. It's better to install it with the small end of the cone pointed out, but it will work either way.

Then, REPLACE the first friction plate of the original stack with the JG-16321-00-00 plate. This plate has a larger inside diameter to accommodate the spring, and take the place of the first plate in the stack. Then stack the rest of the plates in in the normal manner until you end up with a friction plate on the outside end where the pressure plate sits, and one original friction plate left over.


Thank you for your help, I will try this. I have replaced the inner basket with a wiesco basket and put a new inner hub, pressure plate and clutch pack in it in the past and have never been able to make this chatter go away completly. So i am hoping that this mod does the trick.

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