I have a Zinger that is in great shape, recently rebuilt, but I have to replace the spark plug very frequently, or it is nearly impossible to start. The plug looks great, when I pull it, but as soon as I put the new one in, it fires right over with no problem. Any ideas??

 

when you pull the plug does it look tan or does it have some hint of black on the eloctrode? even a 2 stroke the plug should come out tan looking, are you pre-mixing fuel-oil, if so what mixture are you using? here's a couple of suggestions, keep the airfilter clean, and do not over oil it, very lite coat of oil, dirty or to much oil on the filter will cause the engine to run rich causing the plug to foul. if you are pre-mixing instead of using the injector, pre-mix at 40:1, to much oil will also foul the plug. go to a hotter spark plug, this will not damage the engine but will burn the fuel-oil mixture off the plug eloctrode better.