Improved C15 mill with tougher internals and castings, troubled by high state of tune, the big-end being the most likely area of concern. Many improved with CCM bits. B25 had street scrambler styling, conical hubs, and handled better than similar era Japs but ruined by engine reliability problems and nasty vibes – some now run Jap engines! The odd nice one running a detuned mill, but needs loads of care to build one to a reliable spec.
1967-72 247cc (67x70mm) OHV single 25hp, 80mph, 70mpg 300lbs