there are several other twins or large singles out there that have no balancer weights 😉
Yamaha XS650 or SR/XT500, maybe some of the english twins, not sure.
Maybe the counterweight at the crankshaft must be modified as well to find the best compromise in reducing the forces in vertical direction (agains piston) and in horizontal direction, where the counterweight at the crankshaft causes forces itself.
May start with some weighing.
The piston (+0.5mm) with rings and bolt is 414 gramms.
Maybe I have to consult a “motor builder” to find out if he can calculate or measure the needed counterweight at the crankshaft.
Of course there will be more vibrations, but that is the intention, at least for a hardcore chopper 😉
Attached a graphic that shows the conditions. Especially picture C in the upper line is interesting 🙂