I would suspect points or valves need adjustment. The hard run either wore the points rubbing block down so the gap closed up or either the valves seated in, the rocker is a little worn or you slightly bent a pushrod. So, pretend it needs a tune up and check the valves and points.
If thats not then you have to give me the BSA and I'll give you my Honda or Yamaha in trade.
Ken
AHRMA 412
Vintage racing - old guys on old bikes
If thats not then you have to give me the BSA and I'll give you my Honda or Yamaha in trade.
Ken
AHRMA 412
Vintage racing - old guys on old bikes