As the clutch is let in and revs slowly increased (as normal) to take of in 1st gear, the clutch isn't gradual. It is sudden, grabby and noisy. It will stall if abnormally high revs aren't applied. Impossible to take off on hills. Once in a while it works normal. The problem doesn't seem to appear temperature sensitive.
The clutch is NEW! It has been out since replacement and is fine. Gearing isn't too low.
Fully Synthetic oil is used and changed regularly.
Any ideas??
Thanks
I'll bet you replaced the "fiber" plates only in which case you need to either take the steel plated out and have them sand blasted, or preferably "glass beaded", you have a hot spot on one of the plates which is causing the clutch to be "grabby" also not sure if you replaced the clutch springs but if you did and they are after market they may be to high of spring pressure.
Did you install a stock clutch or a after market one? Many times the after market hi-performance clutches are made with aluminum plates and then they add the fiber and the clutch will chatter because the engine HP to to substantial for the aluminum to handle. I highly recommend using the stock Yamaha clutch plates and springs. They are of the highest quality and are the best to use.
Please let me know what type of plates you are running and I'll work from there with you. Also if you cannot get the plates blasted you can take them out and rough them up on your garage floor. Your want to use even pressure and move in a circular motion to scratch them up. Make sure you clean them afterward in mineral spirits. You can buy that at any paint store real cheap.
Good Luck,
RSelvy
Did you replace the springs too? Are they after market? IF so please be sure to compare them to the stock ones you took out, often times replacement heavy duty stuff comes at a price, the springs are to high of spring rate which causes the problem you are having and again the composition of the clutch plate material is critical. Can you please let me know if you replaced the parts with genuine Yamaha parts? This can be a major cause of all your problems. Again I strongly recommend scratching the metal plates if you are using the old ones, if you installed "new" metal plates then he is right, you do not need to do anything to them.
You are telling me he sold you a "good brand" clutch, I have been in this business for over 30 years now and ones opinion of "good brand" can be greatly mistaken simply because your application may differ from others.
The key here for me to help you is I need to know a few things:
By answering these questions I can give you the exact solution to your problem. I know you don't know me but I spent most of my career building strictly hi-performance and racing application motors and chassis. I have worked for all 4 major factory's building engines for them. Please trust what I am telling you.What exact brand did he sell you? I need a name please.
What type of clutch springs did he sell you
Are the clutch springs heavier than the original ones you took out?
Did you visually compare the springs, i.e. count the spring coils. (they can coil bind)
Did you replace the metal and friction plates both?
Are the friction plates aluminum or steel based?
Regards,
RSelvy
I was sincerely hoping you were not going to say Barnett. This is a hi-performance clutch and they are well known for this type of issue. Try this, get a set of stock Yamaha clutch springs and see if this does not help the problem.
What's happening is the springs are so aggressive that when you let the clutch out it's all or nothing. The combination of the plates and the springs will cause this because this particular clutch is best suited for drag racing. A better brand of clutch is made by Vesera but truthfully, the stock OEM clutch is the best with perhaps YZ490 clutch springs.
I have many years in this industry, please trust what I'm saying. Your problem is in the clutch, not anywhere else.
Let me know if I can help any further.
Regards,
RSelvy
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Thanks for the reply. OK, no the entire clutch has been replaced with a good brand heavy duty unit (everything except the basket) including the springs.
I asked the bloke who sold me the clutch about roughing up the steel plates and he said not required for this clutch.
Any other ideas?
Cheers
Phil
BRAND- Barnett, including springs which are heavier than Yamaha.
FRICTION PLATES- Barnett, steel.
I think the problem lay elsewhere. The clutch is new however this problem existed with the old ORIGINAL clutch.
Thanks.
Keep it coming.
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