Any suggestions to lock the motor to tightenthe nut that holds the magnet/final drive sprocket? I have broke my brake cable trying and now use large vise grip between the brake lever and axle nut with rags to protect parts and it works and have never lost paint or broke anything but I can not seem to ever achieve a total lock even with engine in gear, like now tightening up this nut tthe best I get is 70 ft/lbs torque. I have heard of putting rope in the spark plug hole on the compresion stroke. Us farmers have plenty of plastic twine. Any suggestions that won't hurt my pretty bike?
Things you might want to try in addition to applying the brake: Let some of the air out of the rear tire. Have someone sit on the bike, and either back it against a wall, or have the front wheel against the wall, depending which way you need to loosen or tighten. That, with a person on board, and the bike in top gear will make it easier to get things tight. Back wheel should not spin. I have used variations of this technique with great sucess through the years, on both loosening and tightening things. I would not stick anything in the spark plug hole.
I don't think the weight matters much but having someone on the bike is the big thing. The bigger the better? Anyway, they can help steady the bike, and hold it up against a wall. I think this will give you the advantage you need in letting the rear brake/gearbox lock things up. I'm not sure on the steering lock, I think they might just lightly press in.