poor fuel consumption

Message

telefunkin · Wed Jul 01, 2009 4:52 pm

So I've been having fuel issues with my 81 KZ750 H2. I am only getting about 15mpg and am wondering if it is from the jet needles. I replaced my old carbs with a newly rebuilt set and the problem is still there. The jet sizes are correct for the stock setup and I have not done any mods to the bike. I am using the needles from the old carbs and am wondering if they could be the problem. Anyone know if worn needles will cause this kind of drop in gas mileage? My float levels are also good and there are no leaks that I can find. No gas in the crankcase either.

Johnj · #2 Unread post by **Johnj** » Wed Jul 01, 2009 4:57 pm

Ok where is the gas going?

BuzZz · #3 Unread post by **BuzZz** » Wed Jul 01, 2009 9:04 pm

Needles can indeed wear. They can usually be moved up and down in their mounts in the slides via movable circlip and grooves in the top of the needle. The hole in the carb that the needle slides into wears too, it is often replaceable and is called an emulsion tube. All these things could be making the bike rich.

But 15 mpg? That's alot of fuel to lose through jetting. How does the bike run? Jetting that bad would be noticeable. Really noticeable.

Check the air path through the bike. Clogged air filter and blocked/collapsed exhaust? Does the bike roll freely? Dragging brake or bad wheel bearings? Mileage like that should have a symptom someplace, I would think.