I saw this over there. http://cr500riders.com/cgi/yabb/YaBB.pl?num=1212196648
Since I'm not a current 500 owner according to them I have nothing of value to offer over there. Anyway, my solution to loosening or tightening the flywheel nut without an impact is: pull the plug, find TDC then rotate the flywheel about a 1/4 turn opposite the direction you want to turn the nut. Take several feet of CLEAN small rope and feed into the spark plug hole until no more will push in. You are now ready to turn the nut. The piston will compress against the rope and combustion chamber and motor will lock solid allowing you to break loose or tighten the nut. Sure beats the hell out of a stick thru the spokes!