Re: 94 Force 120
If you have aluminum throw-off on the sparkplug--specks from piston on the sparkplug-- then you already have damage. How severe is the question.
First, check the needle setting on the bottom carb. It should be around 1 turn out. If it is correct, then remove the bottom carb and clean it well. Look for a low float setting or general junk in the carb bowl which would result in partial clogging and a lean run. Put a fuel filter between the fuel pump and carbs if there is not one there already.
10 pounds low is not much and after correcting the lean run condition and installing a new plug, the engine may run well. HOWEVER: Look through the plug hole to see if the piston crown is the only part damaged or if there is scoring on the cylinder walls. If in doubt, remove the head and look at the cylinder. It may have some aluminum wipe-off on it, affecting compression. If it does and if it is light, it can be scraped off. heavier accumulations need to be scraped then cylinder lightly honed.
