hebo

Wanted to ask if this cylinder can still be riden or should i not use it because of the nicasil damage around exhaust ports. I can't feel any scratches with my nail, but it seems pretty bad.

What bearings should i buy for a pretty powerful mid-race moped? Hebo manston, yasuni c21..... I saw some Stage6 skf, Polini skf are they any different or just basic skf bearings?