lousy gas mileage

right now on my 70cc I've got a one quart gas tank from a lawnmower. Figured that would be fine for the short hops I make. Went out for a haircut the other day, 16 miles round trip, and didn't make it! Ran out of gas two miles from home, and I had topped it off just before leaving. So that's what, not even 60mpg? What's up with that? And I do a lot of pulling the clutch to roll down hill, and even shutting the engine off on long down grades. Bike runs fine. Checked the plug and it looks fine fine.

Bruce,
Can you offer us some information such as your weight, rear sprocket size and how much wide-open-throttle time you ride? These figures would help determine why you seem to be getting poor milage. The 150 to 160 MPG figures offered by the kit suppliers might be a bit overstated for every condition but your milage does seem a bit low from the norm.
Tom

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I'm no lightweight, around 200 lbs. I never ride with the throttle wide open. 15-20 mph is the perfect cruising speed for me. I have an over sized rear sprocket (52 teeth, I think) because I live in some very hilly terrain and am willing to swap off some top end speed for extra torque. My bike is a Kulana beach cruiser, which I realize is not the lightest bike around either. Still, last year I was driving an 1100cc, four cylinder Yamaha and getting 43 mpg. Something is seriously not adding up here.

The 52 tooth sprocket is certainly not helping your gas mileage. Thats alot of R.P.M.'s at low speed.

John

I understand that's a factor, but that much? I drive a 95hp motorcycle at 75mph and get 43mpg, and I don't have to mix oil with the gas. Going from a 44 tooth sprocket to a 52 tooth sprocket I would think would cause a barely perceptible drop in gas mileage. But 55 mpg? Maybe it's part of the larger picture, which would include my weight, the weight of the bike, the terrain I ride on, my usual cruising speed. Most of these are factors which I can't change. I never took seriously the claimed 150mpg, but if this is the best I'm going to get, then I have to consider whether I want to bother with a motorized bicycle.

wow,cause im getting 180-200mpg with a 44t sprocket and im 120lbs on mostly flat ground at speeds around 25-35mph.

Don't know what else to tell ya. The rest of us are getting well over 100 m.p.g.

John

I'm 300# and I figured the last gallon went thru at a little over 90MPG. And that was mixed 20:1. I'm running 24:1 now and it looks like maybe I've increased mileage to maybe 130.

Well, this is quite a mystery then, isn't it? I'm stumped.

The plug looks fine, just a little gray soot, like you'd expect to see. But, if I did want to adjust the mixture, how would I go about doing that?