I got a reed valve in my 49 cc pocket bike motor and it keeps that spray back off the frame. It's Ment to have a balanced bottom end and big bore kit. Ment to make 4 hp and do 12000 rev at the moment it hits 64kmh and revs out so going for a smaller sprocket soon no peddling ever so far after haveing like 10 66cc and 1 for stroke this is the best motor never eny issues and go's like that out the box. just aim and hang on