You definitely need the right holding tool for your clutch.
Don’t use an impact gun on a crankshaft. Don’t use piston stops or hold it by the flywheel nut. Get a 5/16″ allen socket from Sears or you can put a piece of pipe over an allen wrench for more leverage.
If the taper is properly fit you only need a tiny bit of blue loctite and 25 ft. lbs. on the starter nut.
FAA certified jet engine and aircraft technician,
Nicholson Speedway class champion 2001,
Yamaha KT100 Service Center,
41 years karting experience