I’m breaking in my 72cc Airsal right now.
By modification, do you mean other than matching? Cause that’s all it needed.
I have a stock clutch and 18x43 gearing.
Even babying it for break-in it pulls my 200lbs quick up to 30mph with little throttle. Blasts when I open it a little more.
17.5mm PHBG. Estoril.
I’d say it’s got torque for minimum effort.