So after some investigation i've found out that my Piaggio P501 uses a rotary valve instead of a reed valve. I took off the head today and cleaned off some of the carbon buildup. I'm positive it is getting a strong spark. It hasn't been run in 17 years. and i'm not sure of the compression, there is lots of resistance when turning the engine by hand, but when let in TDC the resistance fades away. The car turns over, and is getting fuel, but will not start and back fires though the carb often. When trying to start, the engine will ocasionally burp, and the rythmic starting noise will pause for a while and usually back fires afterwards. I'm not very firmillar with 2 strokes but perhaps it need new piston rings? any insight?