primary clutch question

[michiganman]

It appears that my belt is not riding all the way to the top of my primary. It is bone stock 07 Attak. I was told that there was a problem with the 06 & 07 and that the fix was to split the primary and have one sheeve machined down to allow the clutch to close all the way. Anyone heard of this problem or fix? Sled still runs great top end but am wondering if there could be more. Thanks for the help.

 

[tttario]

Machining the face allows for overdrive, yes. I would think you would want both faces machined equally for even belt grab. Also, the shoulder need to be machined off of the helix for full shift out. Allen Ulmer can machine and balance your primary and cut your helix for OD if needed.

http://www.ty4stroke.com/viewtopic.php?t=66029

Oh, you will be asked to add your location as it is site requirements.

Welcome!

 

[journeyman]

Yamaha does this for a reason. Less blown belts. They usually will go to about 1/4" down from the top edge of the sheave. You can do the overdrive thing, but in the 2 stroke world you usually had to gear down. Maybe the 4 strokers won't need it...not sure. I tried it (overdrive) on my old 600SX Yammie and didn't notice any gain at all. Well sort of like that. I lost ET but gained MPH. So in essence I had more top speed, it just took me longer to get there. 4 strokes are a different animal though.

 

[170plus]

it works on the apex for sure,you also have to space the helix on the posts or cut the helix on the inside face to allow it to shift out too,then you can gear down to gain on low end and it will shift out and be even faster on top,

 

[michiganman]

Thank you for the info. I just put on the Ulmer Stage 2 kit so I will see what it does this weekend.

 

[trailnazi]

does the ulmer helix in the stage II kit need to be machined also