I was asked to rebuild a OS 50 SX that was lacking in power.

I found that the piston was dished. the guy had flooded the engine and forced the piston through top dead center. The resulting pressure caved the piston in. That engine ran, idled great, etc but just din't have much power.

He had a second 50SX that developed the no compression syndrome. His rear bearing had lost the bearing retainer cage. It was plastic. But the plastic parts did something to the ring. I replaced the bearings and the ring and she was good as new.

Enjoy,

Jim