boardmandan
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Blew 2 yamaha belts in 2100 miles this season. Have 8500 on sled. I am looking at the primary clutch surfaces and there is a noticeable depression near the center of the surfaces. More so on the outer surface than on the motor side surface. Let's see if I can attach a picture. Not the best shot but you can see it. Is this normal or should the surfaces be flat?
Sevey
TY 4 Stroke God
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It's normal for the clutch faces to groove over time. But it's hard to tell how deep the grooves are in the pics. The unevenness of the sides would concern me. Perhaps someone with more experience can comment.
Ms
Ms
R00STER
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The grooves down there will only contact the belt on engagement or very low speeds.
Last season I was going through belts like crazy. After inspection i noticed that i had a lot of play in my secondary's bushings, that I believed was causing binding. I noticed that i was getting different shift RPM's all of the time. Also my clutches were running hot to the touch, letting me know that i had belt slippage. I changed both of the secondary bushings, and that seemed to solve the issue.
I had grooves like that as well, but this past summer I sent my primary to Schmidt Bros and had it serviced and i also had them machine it for overdrive.
Last season I was going through belts like crazy. After inspection i noticed that i had a lot of play in my secondary's bushings, that I believed was causing binding. I noticed that i was getting different shift RPM's all of the time. Also my clutches were running hot to the touch, letting me know that i had belt slippage. I changed both of the secondary bushings, and that seemed to solve the issue.
I had grooves like that as well, but this past summer I sent my primary to Schmidt Bros and had it serviced and i also had them machine it for overdrive.
kviper
VIP Member
When the belt's blew were they all ground up in chunks or de laminated?
sprintcat
Expert
Rooster ,Over drive?
boardmandan
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I think I've gone through 4 or 5 belts since I've owned it, they've all delaminated. Always near wot when a chunk comes out. I put a straight edge on it. Now I can see both clutch surfaces are worn about the same. No shifting problems. Up to around 60mph it pulls strong.
hibshman25
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2018 snoscoot
As long as it's smooth across the wear area I would not be concerned. I see some clutches that are grooved that deep and have a sharp edge that would appear to have been machined there!
kviper
VIP Member
Usually delaminating is from slipping (starts to pull cords out on the sides), all ground up in small pieces is from the belt Rolling over due to alignment issues.
R00STER
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They machine the primary so it will close a little more allowing the belt to ride a little higher in the primary.
Big_Phil
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If its delaminating your secondary clutch is the problem. My brothers sled would delaminate a belt every 1000kms or so, always on a long pull. Changed the secondary from a parts sled we had, went 4000 kms with the low boost turbo added this season and no more problems.
YamBam
Pro
My dealer recommended running a soft compound 8CH or 89L belt to reduce sheave wear and grooves in the primary. Anyone else hear of this? I seem to blow more belts now. Sled seems to perform fine with soft compound.
Big_Phil
TY 4 Stroke Master
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I've never heard of this. You shouldn't blow any belts. I run 11 psi on the trails and have buddy's that run more. We all run the 8dn. None of us blow belts. I get between 1000-1500 kms on a belt before it starts losing a little bit of performance, but they still don't blow.
Don't worry about the grooves at the bottom of your clutch sheaves. Every Yamaha has those. If the compound is a lot softer it will bring your rpms down a bit
SXRPILOT
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Make sure your deflector under your secondary isn't bent up from when the first belt blew. When decelerating from wide open throttle, your belt is loose and can hit it, catching a top cog, then delaminating. Here is how i fixed mine. Made a bracket, used a plastic body dart to attach.
Attachments
gmfamily2008
Pro
Not to hijack the thread,
,but "boardmandan" ,I'd be concerned about that chunk out of your primary clutch.
,but "boardmandan" ,I'd be concerned about that chunk out of your primary clutch.
livewire_101proof
Extreme
I have seen them grooves before, actually I picked up an 08 nytro with only 800 miles on it last year and already had them grooves. My thought is the way the clutches engage stock, primary spring with less engagement or smaller rollers would help it out slot, most people clutching these sleds end up doing that as part of the kit anyways
