I got a 1976 CB250, (UK G5), model, in nice condition which the previous owner left for over a year but didn't bother draining the tank or the carbs before laying it up. It did start but would only run on the left cylinder, the right plug was bone dry indicating to me that the carb was bunged up.
I cleaned the tank and had it lined, cleaned both carbs to within an inch of their lives, refitted them and both cyls fired, pleased with that but noticed when revved it would hang off idle before slowly settling back down. As there were a few things I wasn't happy with I decided to go through the bike, starting at cam chain adjustment then valve gaps, points and timing, the auto advance unit was filthy so that was stripped, cleaned, and lubricated, everything put back together and the hanging revs problem was gone, good chance it was the auto advance unit sticking a bit.
I realised the only thing I hadn't done was the float heights and the question is with regards to the float height, I have searched for a definitive answer and read info in various places and there seems to be differing opinions on float height and how the carbs should be sitting whilst checking the height, FSM says 18.5mm, carbs vertical with tang just touching float needle and choke side at the top, others give a range of heights from 19mm-23mm with the carb slightly tilted, others stating because of the newer fuels E10 etc heights should be increased slightly.
I would be grateful if someone could tell me which would be the best setting and way to do it please?
Thanks
