I want to fit a flywheel weight to my 250 Pro but can't see how to hold the flywheel when refitting it as the weight uses the two holes for fitment, can anyone tell me how they have done it, also how tight should I torque the bolt?

--Put it in gear and depress the brake

or

--Feed rope into the sparkplug hole to keep the engine from turning

or

--Drill 2 more holes

That's a pretty bug fastener.

I guess 70-80 ft/lbs

Use an impact driver to loosen and tighten flywheel nut. You then can hold it from turning with just your hand. Also put loctite on the thread when refitting.