my friend has a trailblazer that has lost a lot of top speed , he has done everyhting to try and fix it (rebuilt it, new belt, cleaned carb), i assume it has to be a problem with the cluthcing any ideas what it could be?

 

Maybe a worn belt?

Steve Lubecki

 

it has a brand new belt

 

Full shift out, it should be at the top of the primary sheeves.
Check the weights.

JIm

 

what could be wrong with the weights?

 

Make sure the distance between the 2 shafts are around 10".This is from center to center.

 

gearing change?
helix?

 

how about compression it seems to me if it was getting close to top end time and lossing compression it would get slower.

 

theres 10" between the shafts, theres 1 1/3\2 inches of belt deflection, compression is good it was just rebuilt and tested

 

It looks like you've got the clutch covered, and it was just rebuilt. I would focus on carb and engine timing.