Since this thread has come alive again I have a questions for those running BJ's.
I have a set of 44's on a 5mm 780cc engine. I get about 1hr run time on 5 gal of fuel. This sound about right or do I have an issue where I'm buring excess fuel.
More power means more fuel consumption - that power has to come from somewhere.
Install some 38's and see your fuel consumption go down. Just don't expect the same power, either.
Alternatively you could also downsize the engine. Bam, less fuel consumption.
I'm not convinced that bigger carbs waste more gas. They let the engine breathe better the air/fuel mix, so of course it's going to be more power and more fuel.
PS: I got at least 1.5 hours if not more out of 5 gallons on my JW 760 with pretty decent power, dual 46 BJs.