when plowing with the xplorer 300 (2 stroke)(air cooled) the other day all was working good until the piston siezed. tore it down and looks like a cold sieze on the exhaust side. it all seemed to be working good until the fan turned on. the cooling fan is right in front of the exhaust. im wondering if the cold air from the fan caused this problem. any thoughts...

 

I dont think the fan had anything to do with it but I think the air temp did. That is a problem with working an air cooled engine real hard in cold temps. Your working the engine real hard so the piston gets real hot. The air temps are cold so that makes the engine go that much more lean. There is a bunch of O2 in the air and that will get that piston even hotter which grows and grows and grows.

Then the barrel is cold, or colder than the piston because of the cold outside air temp. This makes the bore shrink a bit. The piston is already big because it's real hot and then the piston skirt gets sticky and starts to gall on the bore. Friction gets higher and higher and higher until it locks up.

That is one bad thing about working an air cooled engine in cold weather.