lousy gas mileage

[brucemg51]

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.

[2door]

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

[brucemg51]

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.

[Retmachinist]

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

John

[brucemg51]

Originally Posted by Retmachinist

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.

[Cabinfever1977]

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

[Retmachinist]

Originally Posted by brucemg51

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.

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

John

[Norco 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.

[brucemg51]

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

[brucemg51]

Originally Posted by Bikeguy Joe

I think your carb may be set too rich. What does the plug look like?

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?