That engine should be a gem. When warmed up and at idle, simply pinch off the fuel line to the carb. If the engine speeds up quite a bit, then lean out the low speed needle some more. Keep doing this until it speeds up very little when you pinch it off. You will have to reset the top end needle each time too. It has a twin needle carb, not an air bleed carb I think, so turning the low speed needle "in" will lean out the low end. Other than that, check all gaskets including the o-ring on the carb mount and check for piston, ring, or cylinder wear.

OS SF owners now have an option if they need a new piston and liner..... The Leo ABC piston and liner is a drop in fit! See the article at Just Engines. They sell them also....:-)

Ernie ([email protected])