Topic: CB650C gas mileage (I'm out of ideas).

[ABikeNamedTrouble]

It seems most people whose 650s are in good shape are getting anywhere from 50 to 60 mpg.  The highest I've ever gotten is 47, and I average around 44. 

I posted previously about rough engine breaking, etc., but new idle jets (who says pressed in jets aren't replaceable! ha.), tuned mixtures and re-syncing the carbs have cured that problem.  Now the engine runs strong and smooth at all RPMs and throttle settings.  Front and rear brakes are operating correctly and both wheels spin freely by hand: a good strong pull gets me 15 revolutions or so on the front and probably 25 on the rear.  My spark plugs look good as well.  Air filter is clean, tires are inflated to spec.

So, what's the next thing to check??  It seems I should be getting 55mpg, so what in the world could be causing a 10-15% reduction in fuel economy if not the above issues?

Thanks in advance for the help.

[72500john]

mpg depends on alot of things..driving habits,aka do you as they say "dip into the 4 barrels frequently". are you doing alot of highway driving or city driving? sorry guys motor cycle or car all these rules apply. and dare i say it without starting a ruckus. what type of fuel are you using. my opinion..for what it s worth. is try and stay away from ethonal fuels if you can. sorry but alocohol, which basically ethanol is. will evaporate and hence = less mpg. sorry if i opened a can of worms.

[ABikeNamedTrouble]

I tend to get 45 or so in the city; sometimes < 40 if traffic is bad.  My best (47) was a combination of county roads and highway, averaging probably 55-60 miles per hour. 

We can talk about ethanol later, but even the most cynical would't say it drops mpg by 15%.

[trueblue]

My 650 gets on average 5.5l/100km which works out to about 42 miles/us gallon, I don't particularly care how much fuel it uses, it runs well starts first time everytime and is a ball to ride, I don't particularly care that there are other bikes out there that use less fuel than mine, but I think 60mpg is a little optimistic.