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

Discussion in 'General Questions' started by professor, Apr 1, 2013.

  1. professor

    professor Active Member

    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?

  2. grinningremlin

    grinningremlin Active Member

    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.
  3. professor

    professor Active Member

    Grin, my post is not about saving money. These things are toys for me- cheap ones at that.
  4. jaguar

    jaguar Well-Known Member

    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.
  5. MotorBicycleRacing

    MotorBicycleRacing Well-Known Member

    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

  6. Purple Haze

    Purple Haze Active Member

    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!
  7. StrontiumEthics

    StrontiumEthics Motored Bikes Sponsor

    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!
  8. grinningremlin

    grinningremlin Active Member

    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, 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!
  9. wheelbender6

    wheelbender6 Well-Known Member

    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.
  10. darwin

    darwin Well-Known Member

    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.
  11. wheelbender6

    wheelbender6 Well-Known Member

    A 100 mpg motorized bike costs $300-$500. A hybrid car that gets 60mpg costs $40,000. I think I'll ride a motorized bike and save the $39,500.
  12. MotorBicycleRacing

    MotorBicycleRacing Well-Known Member

    Your comparison is avocados to banana's, how can you compare a one person bicycle to a 4
    seater car?

    A 100 mpg motorized bike which costs $300-$500 and that's on the low side would be compared to maybe a Honda Ruckus 50 cc or Yamaha Zuma 125 cc which get 100 to 80 mpg and go 40 mph to 60 mph.
    Used low mileage examples sell for about $2000 where I live.

    True you would have to register and insure the scooters, but they are much more practical
    transportation than a motorized bike.
  13. OlliesDaddy

    OlliesDaddy New Member

    well, any kind of motorized transport is ideal compared to footin' it in my experience.

    of course people need things like trucks, cars and vans, but for my primary mode of local area transportation, i will vouche for my moped. used to take my moped to work, school, buddies' parties, shopping; now if i need to haul something or shuttle people around, then it's time for the auto, but otherwise i prefer the wind on my face while crusin on my moped.

    don't even get me started on nopeds! the urban express was like driving a recliner! suuch a comfy ride!
  14. wheelbender6

    wheelbender6 Well-Known Member

    I wouldn't claim that a motorized bike can replace a car. I would claim that much of the driving we do does not require a car. The motorbike is better for picking up a six pack, a coffee, quart of oil, etc, (weather permitting). I have commuted to work before, but my current situation precludes it.
    I could commute to work if I had an ebike with a 20 mike battery pack, as I need to be on the sidewalk to arrive alive.