Rear pulley mods?
Clutch stall rpm?
#1 issue with hobbits is belt position. Mod vari to drop belt down to the boss at rest (just off the boss by 1mm max)
And mod rear pulley to close more (grind rivets/weld and shave down)
Belt should sit outside of pulley by 2mm or more.
Also what belt are you using?
Please don't say BX. They suck shit