Hear is my question i have black marks on the primary clutch 1/4"
from the top what could be causing this.thanks

sled 97 mach1

Stock sled? Stock clutching/gearing? Stock track? Studs? How heavy is the rider? What belt are you using? How long has it been in there?

When's the last time the clutches have been cleaned? My sled was doing the same exact thing, and I ended up taking the clutches apart, and two of the arms in the primary were locked up, I couldn't move them at all. They were causing the clutch not to close all the way and causing a ton of belt slip.

Also could be caused by running a real hard belt and a heavier rider. I like the -127 doo belt on my sled.

I know i when i use lite tip wheights and do a lot of wide open throttle there is some slipage and the last 1/4 inch or so on the clutch tends to get black.