Don't use plastic spinners with a four stroke. I've tried using the Higley light lock and Dubro spinner nut combo, but I found it was not safe especially if an electric starter is used (it loosens the spinner nut). A double jam nut is needed and after tightening the first nut, I tighten the jam nut against the first nut using separate wrench on each nut. You could get the Vortech spinners and jam nut kit from Dave Brown, which is cheaper than Tru-Turn.