im working on a sr50 old shape with a minarelli engine i just fitted a stage6 70 bore malossi vari and clutch, 21mm carb yasuni z pipe, and polini belt.it has 4.7g rollers.to pull off on the bike you have to have the bike revving its nuts off then the bike will pull off slowly and gradually the bike rides beter as you go faster.i was thinking it needs looser clutch springs?
Sounds like it does need slightly weaker springs plus the rollers are too heavy.....if I HAD to suggest a weight it`d be 3.5-4.2g approx.
I'd say torque spring needs changing or you clutch springs and lighter rollers , if not, then im sure a bike shop could look it over, mine used to do that too, i dunno what happened, but few days after it being slow, it was quick accel and just shot off
