Hello
I have a bsa m20 and wanted to find out a bit more about its history. I have found a frame number on the headstock: z (or 2) 869 and engine number: 1798. I have looked at other m20's and they seem to have numbers starting with wm. I can't seem to find any numbers anywhere else on the bike.would anyone know if these numbers are correct or just part numbers? I have attached some pictures as it might be easier.
Thank you
Alex
Hello Alex, Please see attached for frame number info.. Maybe the actual frame number on your bike is covered with a thick layer of paint? The engine number you provided doesn't seem right as there should be a %M20 prefix or 'possibly' suffix (but numbers seem to be in correct place).
Why don't you put your question to the WDM20 website they may have the answer.
Or if it's a KM20 frame the engine number will be stamped lower down the frame at top engine mounting bracket on the front down tube. The numbers shown don't look genuine BSA. All the best, Glenn
WD replacements engines would just have 4 digits as yours does.