Primary sheaves wearing?

[Superman]

For the clutch experts out there. My Attak has about 2,300 miles and the primary sheaves have some grooves in different locations. The worst ones are down @ engagement and another (not as bad) is somewhere around 3/4 the way up the sheaves. Has anyone else ever had this happen? The only reason I caught this is because I blew a belt @ 1,600 miles and I have NEVER blown a belt on any Yamaha I've owned. My clutching is 100% stock never touched. I have seen 11,000 RPMs alot this season. I also notice that my sled/clutching always feels snappier anywhere below full throttle. Based on what I see and feel "I THINK" I have a belt slippage problem causing the sheave wear.???? But how can this be???? Not enough primary weight maybe? a spring issue perhaps??... My Secondary clutch sheaves appear to be fine. I keep hearing that Yamaha is kind of anal when it comes to clutch parts. Any help and theories would be apperciated. Thanks.

Only change to my sled is the 1.5" ripsaw. NO Studs.

 

[LazyBastard]

It is normal on engagement. Very much due to being a high powered sled, and thus, having to be geared very high. There can be SIGNIFICANT slippage on engagement, and there is nothing you can do about it except lower the gear ratio. If you do this AND overdrive your clutches, then you can remain the same, or close to where you were on the top end, ie, 5% overdrive and 5% gear reduction. 5% gear reduction can be accomplished by changing to a 40 tooth bottom sprocket.

 

[SledFreak]

It is normal on engagement. Very much due to being a high powered sled, and thus, having to be geared very high. There can be SIGNIFICANT slippage on engagement, and there is nothing you can do about it except lower the gear ratio. If you do this AND overdrive your clutches, then you can remain the same, or close to where you were on the top end, ie, 5% overdrive and 5% gear reduction. 5% gear reduction can be accomplished by changing to a 40 tooth bottom sprocket.

How do you overdrive the clutches? Changing the angle of the Primary shieve to get a full shift.

 

[LazyBastard]

The primary can be cut at the bottom inside to allow the faces to come closer together. An alternative is a "speed sheave", but they are a different angle than stock, and have the unfortunate side-effect of being harder on belts.

With the secondary, spacing the helix further out, or cutting the bottom of the ramps deeper will allow the faces to open further.

 

[UPsledder]

One thing that will help slippage is to take your belt off and wash it in warm water and soap every 500 miles or so. It will grip the sheaves much better. My 03 RX-1 did wear the sheaves on the primary and was replaced under warranty. Since I have been washing my belt as mentioned there has been no problems on my RX-1 or my Apex. I hope this helps.

 

[Superman]

Thanks guys, I don't think the wear is really bad but I never noticed anything like this on my RX-1's. I scuffed up the sheaves with scotchbrite today and cleaned everything up. I'll evaluate the situation next fall but hopefully its nothing.