1989 Force 125 piston/head gasket help

[dogboy8]

finaly got the head off this thing, and overall it looks pretty good. I need to clean the crud out of the water passages (some sand in there) and make sure none of it is in the cylinders before I can rotate the crankshaft, but what I can see of the cylinders there is no scoring ( I overheated this baby pretty good). In fact, you can still see a very faint cross hatch pattern as would be left by a cylinder hone. The tops of the top 3 pistons are perfect, however the bottom piston looks rough, almost as if it had been pounding against something. The combustion chamber in the head looks perfect, just like all the others. Also, that bottom cylinder tested 5 psi lower than the top 3. Any clues???? Thanks a million for all the help. Greg

 

[jim dozier]

Re: 1989 Force 125 piston/head gasket help

Usually that would indicate that a busted piston ring was bouncing around in there but your compression seems OK so I'm wondering if that may be from a repair in times past. Has the head ever been off before? Perhaps a previous owner had a problem, had the cylinder honed and replaced the rings but not the bunged up piston. The only down side to the dents is they make hot spots that are prone to cause pre-igniton and detonation.