Do you ever wonder why these things get lousy gas milage?

professor

professor

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I mean, compared to a moderate size car (3000 pounds/ 30 mpg around town) the bikes should get 10 times the milage at a tenth the wt. Right?
My 89cc gets 120 mpg (w/generator, 2 jackshafts and 3speed bike hub)
My 212 gets 120 mpg (w generator, 2 jackshafts and straight drive)

I am sure without having to power lights and having a more efficient driveline, it would be better, but even then, it would be about half the value of the wt/mpg ratio a car gets.

I am always asked what milage the bike gets and 120 sounds great until I think about it for a while.
How about you guys?
 
If you go mini-motorcycle (what I call a tweaked out frame mount) there is going to be much drag.If pedaling it through all gears without the motor is too much work you have a scooter/moped.89cc's is pretty big, plenty of scooters that run with 50cc's very well.There's a chart here somewhere that shows the exponential need for power after a 35cc.

The EHO35 got roughly 175 180 mpg, the Tanaka PF4000 roughly 155 165 mpg and I can only go 4mph faster, though the overall power is considerably more.

Remember to take into consideration a motorcycle/scooter/moped won't get you home if the engine craps out, you pay no reg/insurance, the cost of tires and parts in general is measly compared to other forms of transport.If that doesn't bump your overall savings, pedal pedal pedal, or work up a fairing, OR get a nice scooter.
 
4 strokes naturally get better gas mileage.
the bike weight is a main factor when accelerating, not much when cruising.
2 strokes are a sloppy design unless you go fuel injected.
 
It's all about streamlining or the resistance of pushing through air.

Modern cars are much more streamlined than a motorized bike or even
a motorcycle with a fairing.

Efficient streamling allows you to run higher gear ratios and use a fraction
of the HP of an upright rider on a bike which is like pushing a barn door
through the air.

Look at any high mileage competition like Craig Vetters and the first thing
they do is a fully enclosed fairing.

Mileage contests with motors like we use get the rider to lie down in a
very streamlined body and they get hundreds of miles to the gallon

professor said:
I mean, compared to a moderate size car (3000 pounds/ 30 mpg around town) the bikes should get 10 times the milage at a tenth the wt. Right?
My 89cc gets 120 mpg (w/generator, 2 jackshafts and 3speed bike hub)
My 212 gets 120 mpg (w generator, 2 jackshafts and straight drive)

I am sure without having to power lights and having a more efficient driveline, it would be better, but even then, it would be about half the value of the wt/mpg ratio a car gets.

I am always asked what milage the bike gets and 120 sounds great until I think about it for a while.
How about you guys?
Click to expand...
 
I have been trying to maximize fuel mileage on my 49cc HT, so far my best is 173 miles on one gallon. My avg. is more like 140-150. Even at these rates of fuel consumption, it's pretty thirsty compared to a good 4 stroker, plus the added expense of 2 stroke oil. I think fairings are the way to go, now that I have reduced internal friction about as much as possible. Also considering tweaking the timing, as neither ignition nor piston port timing is optimal, but I doubt it'll help much, these engines just aren't very efficient and were designed to be cheap to make back when gasoline was very cheap. Different wheels would help a lot with aerodynamics, but I like the look of spokes, image vs. max effect!
 
Re-jetting and slightly increasing the compression could probably help with better mileage, but I agree there isn't any "cutting edge" technology going into these bad boys, but they are FUN!
 
Diamond frames effectively turn the body into a parachute above 15-18mph.Fairing a diamond frame has it's own difficulties, not to mention the sidewind problems.
Though it's recumbent based, my fav site for aero-dreaming is http://www.recumbents.com/wisil/whatsup.htm, some good ideas there.The front fairing on my LWB bent gave me headwind cutting, wind off my body, pushes my cap down instead of blowing it off, and tailwinds are a blast!
 
I think you could approach 200 mpg on a well tuned recumbent in a flat area due to low wind resistance. I just don't like the way recumbent bikes handle in traffic.
 
When it costs $3.50 to fillup and goes 120 miles who cares about mpg? I ride full blast whenever there's a clear path ahead. Have fun and enjoy. Guess it might matter to some though.
 
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