I tell a lot of people this.
The low end troubles can maybe be easily fixed, following this:
Check how high the belt is riding in the secondary clutch. If it is not about 1 to 2 mm above the sheaves, there is a cam on the side, loosen the 3 bolts and turn it, I think clockwise. Then tighten it back up and take it for a spin, then see how high the belt is riding. It should be 1 to 2 mm above the top of the sheave. This will greatly improve bottom end. If you make it ride too high the belt gets too tight and the belt squeals when the machine is idling and it sometimes even drives away at an idle.
Try it out.
"Might Be Crazy But I Ain't Dumb" - Cooter
The low end troubles can maybe be easily fixed, following this:
Check how high the belt is riding in the secondary clutch. If it is not about 1 to 2 mm above the sheaves, there is a cam on the side, loosen the 3 bolts and turn it, I think clockwise. Then tighten it back up and take it for a spin, then see how high the belt is riding. It should be 1 to 2 mm above the top of the sheave. This will greatly improve bottom end. If you make it ride too high the belt gets too tight and the belt squeals when the machine is idling and it sometimes even drives away at an idle.
Try it out.

"Might Be Crazy But I Ain't Dumb" - Cooter