clutch slipping?

hi again i bought a used 04 about 2 months ago and finaly just got to ride it saturday. well i change the oil filter and oil used amsoil 10-40 oem filter. the oil level was just about a1/4 low on the upper dipstick, anyway after riding about 10-15 minutes i noticed that the tranny was slipping possibly the clutch? i would twist the throttle and hear the engine rev but it was not accerlerating like it should felt like there was some slippage in the clutch. anyway the dealer i purchased it from said the guy used to hare scramble the bike could it be that there is a slipper clutch in there ? anyway i gonnig to drain the oil and pull the cover, just thought i ask before i did. also i did install new chain and sprockets went the 14-47 gearing not sure if i like that yet going to try a 48 next time and most definately a 5-6 oz. weight on the flywheel. had the bike stall out while in the air over some jumps yesterday only to restart on landing, not to comfortable with that, especially over some of the longer jumps. hope the flywheel weight helps. also how far can you safely slide the forks up into the tripple clamps? currently i am at the first scibe line i wasn't sure if i can run them safely at the second line or not? just trying to help the bike turn a little better than it does. well thanks gentlemen for the suggestions ahead of time and thanks for all the help in the past.

Is the amsoil a full synthetic???

If it is, full synthetics are known to cause clutch slipping, because the engine oil and trans oil are shared; therefore you can run either regular (Dino) oil, or a semi-synthetic like Yamalube 4r, but don't run a full synthetic with friction modifiers.

yes i believe it is had it left over from when i rode a honda. amsoil 10-40 synthetic. that would be awsome if all i got to do is change the oil would rotella be allright or what oil should i run? did some searching on it just not sure what to run yet. but the amsoil is comming ou for sure. thanks flintlock

i am running amsoil full synthetic that is compatible with wet clutches and i have no problems.

on the 04 fork there are three marks on the forks 5-10-15mm i believe and you can run your forks on any of the lines, with high speed stability being the only drawback to running your forks higher in the clamps.


thanks fast frank i going to try the second line and see if that helps. haven't drained the oil yet but i'm going to in a little while then i'm going to pull the clutch cover can you visualy tell if the clutch plates are gone or do you have to micrometer them? just hanging around the computor thanks both of you for responding so quickly

to be honest with ya ive never replaced the clutch in my bikes yet, i beleive you can look at the friction plates and there should be fiber, the other plates should not be glazed,my 426 went for 4 years without clutch replacement and the guy i sold it too is still running it with factory clutch to this day, check your clutch adjustment, there should be freeplay at the lever.


it seems fine as far as adjustment i usally keep a gap the thickness of a nichol at the lever. i did drain the oil it was a light black and looked thin, goin to pull the cover tonight. thanks john

Hopefully others will respond that are more qualified to answer...but I know that I've heard on here NOT to use full synthetics since they have "friction modifiers" in them that will cause clutch slippage. The Honda you had, I believe has seperate chambers for the engine oil and the transmission, while the Yami shares the oil for both.

As Frank stated, maybe your Amsoil is compatabile, but I would make sure.....

my honda did have the seperate chambers, tranny side and engine side. i noticed more as the engine got warmer not at first just the more i ran it.still havent pulled the side cover off yet. but i will said that earlier before dinner , now it's well after.

Send a private message to :


He is a resident "Guru" who will always give great info, especially about Yamaha's.

He may just show up on here tonight anyway.

yes greyracer has been a big help to me before. i did pull the cover off and removed the pressure plate and friction plates just a tiny bit of grooving on the basket i could hardly feel it when i ran my finger nail across it. don't own a micrometer probably woulden't be able to see it if i did ( eyesight and 50) i couldent see anything wrong i there even with the glasses on, but i no expert, just figured i give it a shot. one of the friction plates some where towards the center did look a little different wasn't as wide as the others. not the thickness of the friction material just seemed smaller than the others.

is it necessary to loctite the clutch bolts when you reinstall 10mm 5.8lbs torque , the one that hold the springs on to the pressure plate?

I do not use loctitie when I change my clutch.

Fully syn oil should not cause this - I run 100% Syn Mobile1 - no issues what so ever -

How do the plates look and the basket?

the friction plates looked like they had about 1/32" -not quite a 1/16" of friction material left on them they appeared to be steel plates, i did not pull the basket, is there something that could slip behind that? the basket fingers did not appear to be groved but on the inside of the fingers it appeared that some of the steel plates left some marks

On the subject of oil, it is only the EC II oils that can potentially cause problems. I recommend a high quality full synthetic JASO MA oil. I use Amsoil MCF.

If your clutch slips, here are some possibilities:

> Improper adjustment. Be sure there is free travel at the actuator arm, too.

> Weak springs. Measure them per the manual, or just replace them.

> Worn plates. The manual gives a minimum thickness for these, too. If they wear too thin, there is the chance that the pressure plate could bottom against the boss, at which point it could no longer compress the plate stack. Plate wear will lower the applied spring pressure in any case, although not a great deal.

> Hardened plates. Burned or overheated so that the friction characteristics have dropped off.

There is nothing behind or within the basket/primary gear that can slip. It could break, but not slip. Grooved basket fingers and boss splines normally cause the clutch to grab or drag long before it gets bad enough to make it slip.

Hope that helps.

thanks grayracer i looking to just go ahead and purchase the friction plates and steel plates i guess and new clutch springs. i looked at they have barnett for $139. shipped do you think barnett is any good or what would you recomend and where can i purchase. as always thanks again

Not wanting to hi-jack this thread but. On my new 05 yz450 ( maybe 20 hours ) I am getting some odd tranny slipping or maybe the clutches slipping.

heres the screnerio: Drag racing at the dunes, and I start in 2nd then pop into 3rd.. and then hit 4th.. Some times when i hit 4th i can feel it grab and maybe even acelerate a lil... but then BAM the bike does this neutral type action ( no acceration and the rpms scream like i just went into Neutral ) Only once I let off on the throttle ( 1/4 or 1/2 turn ) will it seem to kick back into gear and be just fine..

What in the hell just caused that?

What in the hell just caused that?

Sounds like the engagement dogs on your gear are toasted.

??????? :thumbsup: Dogs? New bike!!!! Thoes dogs are in the Tranny? or is this a clutch thing.. :thumbsup:

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