Hehe. Ran a Mikuni for a while on an old Harley.
Had a hell of a time keeping it tuned. I knew a giant of a bro who ran one on his shovel, so I caught him at the local dive one night and asked him what the trick was.
He told me to fire her up, give it a good run till it was certain it was at top temp, set it level, then tune it.
He went on to say to do that every time you popped it off and you wouldn`t have any more problems.
I bought him a beer and bought me an S&S the next day.