If it was me I'd put it back in the original position and go and do a few plug chops. You may get a starting point if you ask Amal or from the owners manual but it all depends on levels of wear, inlet and exhaust pressures (type of air filter, silencer etc) so you need to be able to tune it to match the bike. It's not tricky. Do you have the Ratio book? There is plenty of info in there on carb tuning.