Re: 1990 Force 90 hp piston damage?
First remove the cylinder head and asses the condition of the cylinder itself. If the cylinder is not scored (not very likely) Then replacement of the piston is relatively easy. Just remove the carbs and manifold with reeds. Reach in with a 12 point 1/4 inch drive, 1/4 or 5/16 inch socket depending on engine, and remove the big end of the rod. push out the piston and rod through the back end of the engine. Be sure to retrieve all 16 rollers and the two bearing half cages. You must press out the wrist pin and if you use a stock piston again, you must use a special tool to space the needles on the rod small end when you press in the wrist pin. Wiseco uses circlips on the wrist pin and no special tool is needed. When you re-assemble the big end of the rod you must use a sharp pencil point or dental pick the be sure the cap is properly aligned (very important! work slowly and carefully) then finish torque the 12 point bolts to 180-190 inch pounds. 5/16 are higher, but I rarely do them and forget the torque number. Should be in the manual though.
If the cylinder is scored, or out of round or worn by more than 2 thousands, then the block needs to be rebored and must be completely disassembled.
