Hi. I'm looking for advice. My son has a blaster. He rides it and I get to fix it. Problem is, I don't know anything about 2 strokes although between us we're learning. Last time it broke down we replaced the piston and had the cylinder rebored to fit. We put in a new plug and it ran great....but only for 1 day. The next day it wouldn't start at all. It sounded like it was going to but it just wouldn't. We took the top end off to check and it looked OK except for oil on the plug - not 2 stroke oil. We put it back together and put in another new plug and it works ok again but I'm worried about the oil getting into the cylinder and fouling the plug again. Someone told me that it could be a cracked crankcase (sounds serious) or a leaky crankshaft seal causing transmission oil to get in. A crankcase seal sounds like something I could handle but I've no idea where this is or how to check it and replace it. I don't want to go to a dealer because we got ripped off pretty bad last time we did that. Does anyone know where I can get more info on this problem or details on how to check and replace the seal. Any help would be appreciated.