Pete before I scrolled down to your possible solution comment, I had also worked out from your first two pictures that 1/4" off each side of the lug would line the later sprocket up and fit between the plates. As for chain adjustment, It looks like the M20 system could be adopted.
Although to my mind it's a stupid system......As is the rear chain adjustment.:rage: Why they didn't just use the tried and tested simple methods adopted by other manufacturers is a mystery to me. Ron
The B33 frame has a bolt going through the plates where the forked part of the M20 adjuster goes so I will probably get away with just extending the adjuster to replace that bolt. Although I think some of these adjusters are already in that form (65-4596), if I can get hold of one.
Hi Pete, We have an 1947 B33 which also had a later box fitted with the same one side cut out as your picture. Have not checked if that cutout was correct regarding the chainline but replaced it with a correct early box.
They are nice little lightweight bikes but I agree that the early box is probably to light for the 500.
For me, cutting down the feet of the case would be out of the question.....you also have to remove the ribs which supports the feet. If I really wanted it I would first concentrate on modifying the plates in a way so they can take the later box.
thanks Ian, I think I have a spare case in the parts bin but I'll keep the offer in mind if I can't find it. I hope to get to Torrington as soon as this virus allows!
I am a bit concerned about the strength of the case if the webs are cut off but thought I'd go that route before making new plates. What's the worst that can happen? :thinking_face: :fearful: :scream: