According to Rupert, for the year ('69), this bike should have a 398 (butterfly) or Concentric AMAL
926. It actually has a worn out Concentric
626. Probably fitted aftermarket. I rebuilt the engine using
an 8.5:1 piston although have no plans for a different cam, but I may do some work on the inlet port. What are my options? Can I get my AMAL
re-bored and new slider? If so, what jetting should I aim for?
Or should I look for a different model and if so which one and what jetting. Compliance with original is not necessary as frame and engine are not matching. I have a lathe so could attempt re-boring the 626 and machining up a new slider although unable to incorporate the choke slide. Would omission of this be a problem if I could put a 'hit and miss' choke between air filter and carb?
I expect I could run the bike with the old carb but as its not standard and possibly fitted with dubious jets and needle and is well worn, I need a datum to start from.
Any help would be gratefully accepted.