Hi mr jims, i was thinking about this and wondering if your sparkplug is right one for mower or plug is too cold as they say,perhaps worth a try, dont go too hot though as could damage engine..besides that all suggestions so far i recond is worth looking into.reducing oil a little and looking or changing muffler definatly a goer.. next obvious thing would be to check ring specs, or even oil ring could be stuffed ...Toroman
