If the M frame number suffix is genuine, then it is not a long wheelbase frame. LWB frames have room between the magneto/magdyno and rear mudguard for a toolbox; ie. the extra length of LWB frames is all in the rear frame tubes, and they do not have the M suffix.
Thanks for that, Brian,
Yes the frame number is genuine as its stamped on the frame, although the engine has changed.
Which models had the long wheel base frame ? , was it just flyers up to 28 that had long wheel base frames ?
Here’s a spanner to throw in the works. I have two 1927 frames both long type and both with M suffix’s and both are authentic factory stampings in the right place (they did vary where they are stamped). One is ‘Bitsa’ a January ’27 registered FS the other is a frame only and has no known history but is dated as being approximately March ’27 and was a 500cc Flyer.
I have seen other long frame models with M suffix’s. Anything after 1928 will be a short frame.