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Discussion Starter · #1 ·
My '02 XC 500 SP revs to 8600 or 8700 rpm at WOT. But it seems to have lost some top-end speed. If I hold WOT, it will pull that higher rpm all the way to top speed. But, if I hold partial throttle, to keep it at, say 8200 rpm, it will top out around 60 to 80 mph, depending on snow conditions.

So, I think I have a problem with the clutches. What is a likely cause?
 

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Huh? So you don't hold full throttle, and it doesn't wind out all the way, or go as fast? Sounds pretty normal to me...
 

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sounds like a clutch binding problem.
 

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Discussion Starter · #4 ·
ripperd said:
Huh? So you don't hold full throttle, and it doesn't wind out all the way, or go as fast? Sounds pretty normal to me...
No, if I DON'T hold full throttle, it DOES wind out all the way--8200 rpm. But it won't pull higher speeds. If I hold WOT, it over-revs by 400 to 500 rpm, and still doesn't have the top end speed it used to. On long runs on hard-pack, I used to see 100 mph on the speedo. Now, 90 mph is about the end of it.




madcow said:
sounds like a clutch binding problem.
Would it be binding on the primary or the secondary?
 

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thats for you to find out.

remove primary, take out spring and see how the sheave moves.
take apart secondary and inspect helix/buttons.
 

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Oh, I see. Your peak power is at 8200, not at 86 or 8700rpm. I'm used to high revving sleds :p It wasn't apparent that your target rpm was 8200 from your first post.
 

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Discussion Starter · #9 ·
Yeah, sorry, after re-reading my post, it wasn't very clear.

Yes, my target rpm is 8200.

I'll start by taking the clutches apart.

But, it doesn't sound like a weak spring to anybody?
 

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bad spring would have your rpms way low.
 

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Discussion Starter · #11 ·
I took apart and cleaned the secondary clutch. It was a little gummy inside, but not bad. The buttons are a little worn, but don't seem too bad.

But, the primary clutch is a different story. I found a little rust on the chrome shaft between the two sheaves.

2010124195449984_13597.jpg


And some pitting on the black shaft where the outer sheave slides.

2010124195417187_13597.jpg


The outer sheave does not slide completely freely. Can I use some emery cloth on the pitting on the black part of the shaft? Or, even a file? On the chrome part, I don't think I'd want to use that, but maybe some fine steel wool. What suggestions does anybody have?
 

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you can try some emery cloth.
 
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