YZ 426 clutch grabbing

[rmx]

I recently bought a 2000 YZ426 that has been at best unloved... most fluids were low(or empty as for the rear master cylinder), the thing sounds like a plane during take-off and the clutch was refered to as an on-off switch by my best friend.

With that said, all immediates have been tended too, now the clutch. I now about the work around and think it is great, I wasn't really sure it wasn't my only solution though.

I figured I might as well take a look at it too see what condition it was in since the bike is like 9 years old. When I pulled it apart the friction plates didn't show any visible wear, but the metal drive plates looked severely glazed like some old flywheel from a teenager's beat-up mustang. I used a medium grit polishing wheel on an angle grinder and did both sides of all plates. I also cleaned the entire clutch pack with brake clean and reasembled.

Once I got it closed up and oil in the case I tried it out. The clutch is smooth as can be. I think this was all due to lack of maintenance, dirty oil on the friction plates...no proof but thought this might be of interest.

[Brett1981]

Yeh the same thing happened to me and I cleaned up the metal drive plates to fix the problem. Only thing was, I noticed the clutch slowly returning back to normal (on/off switch) towards about 3 hours use with new oil in it. So I hope it never goes back to on/off for me or you.

The guy I bought my bike from says it was an 02' model. I bought it for cheap because it wasnt well looked after. It sounds like a plane too gives me headaches after a couple hours riding.

I want to quiet mine down are they supposed to have packing in 4-stroke mufflers do you know?

[rmx]

there should be packing in 4 stroke mufflers. My problem mostly is the 2 inch tip with no spark arrestor. Also, the bike came with a Titanium 4 full exhuast that is known to be noisy so I am running way to lean with that much air flow. I have ordered a spark arrestor and carb jet kit for it in hopes that will quiet it down as well as cool my pipes(lean burn giving me cherry pipes).

[642MX]

I recently bought a 2000 YZ426 that has been at best unloved... most fluids were low(or empty as for the rear master cylinder), the thing sounds like a plane during take-off and the clutch was refered to as an on-off switch by my best friend.

With that said, all immediates have been tended too, now the clutch. I now about the work around and think it is great, I wasn't really sure it wasn't my only solution though.

I figured I might as well take a look at it too see what condition it was in since the bike is like 9 years old. When I pulled it apart the friction plates didn't show any visible wear, but the metal drive plates looked severely glazed like some old flywheel from a teenager's beat-up mustang. I used a medium grit polishing wheel on an angle grinder and did both sides of all plates. I also cleaned the entire clutch pack with brake clean and reasembled.

Once I got it closed up and oil in the case I tried it out. The clutch is smooth as can be. I think this was all due to lack of maintenance, dirty oil on the friction plates...no proof but thought this might be of interest.

The 2000 was known for a grabby clutch. You might find this interesting: https://www.thumpertalk.com/forum/showthread.php?t=461631

[rmx]

Thanks 642MX, I have read this and do appreciate the link. I will eventually put a new clutch pak in but am happy that the a little tlc has me working smooth for now. I went for the '00 model for durability and price, I can't afford much atm and delaying a clutch for 6 months or so really helps.

[grayracer513]

I've seen people (me included) "clean up" a clutch this way and get temporary results from it, but the clutch typically reverts to its old habits rather quickly.

The '01 mod really only requires the boss spring, spring plate, and the innermost friction plate to work, although if the steels are not fairly flat, they may cause the clutch to drag a little, post-mod.

[seehogs]

I rode my 2000 426 with it's grabby clutch for 3 years. You get used to it, just give it more gas when you take off. Don't try to be smooth like a street bike because it will just beat the clutch up.

[BC3]

Probably not applicable here but I used to ride TT 500s

and one day while visiting Dick Manns shop in Richmond CA.I was talking to

him about clutch grabbing...He said to put a washer under one or two of the clutch springs (Giving them more pre-load) and try that...I did and for sure the grabby-ness went away...

Springs right next to each other....

[grayracer513]

Probably not applicable here but I used to ride TT 500s

and one day while visiting Dick Manns shop in Richmond CA.I was talking to

him about clutch grabbing...He said to put a washer under one or two of the clutch springs (Giving them more pre-load) and try that...I did and for sure the grabby-ness went away... :

Springs right next to each other...

This is kind of an old school trick. Its intent is to deliberately cause the pressure plate to tilt as it lifts. When re-engaging the clutch then, the pressure is applied more gradually, rather than all at the moment the plate contacts the clutch stack (this is also the principal on which the '01 mod works).

The thing that may spoil this in the case of the YZF is that the short push rod is specifically designe to prevent the pressure plate from tilting, even (or particularly) when the springs don't provide even pressure. Still, it would be an easy thing to try.

[RogerDedrick]

Thanks 642MX, I have read this and do appreciate the link. I will eventually put a new clutch pak in but am happy that the a little tlc has me working smooth for now. I went for the '00 model for durability and price, I can't afford much atm and delaying a clutch for 6 months or so really helps.

When you can update it with the 01 parts you will not regret it. It makes a world of difference.

[rmx]

So a new clutch kit is not a fix?

[grayracer513]

A new 2000 model clutch is not a fix, no. It will work "OK" for a while, but will return to its grabby self soon afterward. A new '01/'02 clutch kit WITH the addition of the boss spring and spring plate, neither of which are expensive, does correct the problem.

Note that the innermost friction plate in the late clutch is distinguished by having a slightly larger inner diameter to make room for the spring and plate.

[buzzgrizz]

Get a Hinson pressure plate it will make a huge difference.

[divebobber]

Probably not applicable here but I used to ride TT 500s

and one day while visiting Dick Manns shop in Richmond CA.I was talking to

him about clutch grabbing...He said to put a washer under one or two of the clutch springs (Giving them more pre-load) and try that...I did and for sure the grabby-ness went away...

Springs right next to each other....

Tried it on my grabby 2000 426 clutch. Still just as grabby. I'll have to go with the 2001 mod. Nice try anyway.

[rmx]

Well Grayracer513 was right, it doesn't last...but for a different reason than I thought. The problem doesn't seem to be the "glazed" metal rings, but the fact that I soaked the friction plates each time I worked on it was "fixing" it for a short time.

I did try the washer under the spring and had no luck. During a recent look into the problem found out the stock system lacks oil transfer, the clutch boss, #1 & #2 puchrods are part of the problem and the spring added was insurance but work well together.

We switched back to Amzoil synthetics on both bikes and also added Amzoil clutch addative(friction modifier). First day has gone good, will let you know as more time passes.

[grayracer513]

The YZ426 clutch (as with all YZF's) is pressure fed through the main shaft by oil fed from the filter well, through the external manifold, and into an oil feed pipe that runs from the right side of the crankcase (where the banjo bolt goes in) across to the bearing pockets on the left side of the trans. Another upgrade that all but the earliest 426's got was a drilled clutch boss. The boss should have a row of 3 holes drilled into the splines near each spring peg.

You might do well to check up on the condition of the entire oiling system. Perhaps upgrading to the '01 push rod set with the ball would help with oil delivery to the clutch as well.

[rmx]

Update on the 2000 426...

New wheel bearings/seals

new 14/52 sprocket and chain

installed 2001 inner friction plate with spring and ring

installed Twisty pilot screw set 4 turns out

installed #48 pilot jet

new brake pads

new throttle cables

new grips w/throttle

this is on top of:

FMF Ti4 full exhaust

FMF jet kit

Found bike already has Hinson basket

drilled extra holes in clutch hub

Moose intake filter

new fork seals

Now have about $1650 total in it and love it, still need some minor things like replace a few screws and missing tank rubber latch. We rode at Utopia (Defuniak Springs, FL) today first time for MX...had to get my buddy to ride my bike I was so pleased with it wanted a second opinion:ride:

Thanks for all the help and comments leading up to this.