60 MPH...achieveable? Who cares?!? Let blueprint an engine!

Discussion in 'Motorized Bicycle General Discussion' started by DVBikes, Mar 18, 2010.

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  1. Creative Engineering

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    Wind resistance becomes a "HUGE" factor at about 120mph.

    At about 80 mph "air" begins to take on the characteristics of a fluid...This is why airplanes fly.

    At about 100 mph...ground based vehicles are severely affected by wind resistance...the effect is nearly exponential from about 120 mph.

    I can see the dilemma...at 185-190 mph!

    Jim
     
  2. Creative Engineering

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    Yes...

    And as always, logic will prevail...good post exavid!

    Based on what I have seen...1/4 mile will be more than enough to wind the little bugger out. My shop is on a dead-end street that is almost exactly 1/4 mile, and DV gets the bike to full speed in a fraction of this distance.

    Jim
     
  3. corgi1

    corgi1 New Member

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    Is there a sand pit at the end too slow it back down?lol
     
  4. foureasy

    foureasy New Member

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    are you going to build a chamber for it? boost ports and multiple transfers seem necessary to me. im very interested in your plans for the motor.
    clay
     
  5. DVBikes

    DVBikes New Member

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    No Basicly its 3 signs and then a lovely ditch. Ok thanks for the coaster brake joke. Ive been messing with small motors for about 5 years. Go peds were big where i live. and i never thought this would make 5 pages. ahahaha
     
  6. Creative Engineering

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    I will definitely make a tuned pipe for it...I have a chamber design that I tested last year...it worked great!

    I'm just starting the tuning process...so honestly I really don't know where I'll go from here. It's a daily process of looking at what happens based on modifications. I will post my findings as I go along. I really don't expect that there will be anything out of the ordinary that will make these engines go.

    P.S. I totally respect all of the work you have done. Most people have no clue as to the amount of hours that go into building a high performance engine.

    Jim
     
  7. bairdco

    bairdco a guy who makes cool bikes

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    as opposed to the 15 minutes it takes the guy in china to assemble the stock motor with a hammer.
     
  8. corgi1

    corgi1 New Member

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    And a screw-driver lol
     
  9. Creative Engineering

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    lafflafflaff...That was good Bairdco!

    Jim
     
  10. foureasy

    foureasy New Member

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    i am not opposed to hammering an engine into submission
     
  11. Creative Engineering

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    lafflafflaff...And if it really misbehaves...it is doomed for the scrap bin.

    Jim
     
  12. skipu

    skipu New Member

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    i think its possible minor stuff gets me to 39 to 41 you ony have to pick up 19 to 21 mph super light wieght and gearing is key but that motor extra rpms i see it doable on a road race bike at full tuck lol !!!!!!! cant wait to see it !!!
     
  13. RedB66

    RedB66 New Member

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    I think this guy is doing 60MPH. Get out your rubber suit.
     

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  14. superschwinn

    superschwinn New Member

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    no way your going to go 60.. and at least not blow ur motor up

    not enough everything unless your under 100 lbs and your wearing armstrong style spandex with a stupid helmit..

    gotta hand it to you for trying tho.. have to beat the wind resistance. and you aint doin it unless ur down wind or something. need bout 70-100cc's at least
     
  15. superschwinn

    superschwinn New Member

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    loooool..
    thas the ticket.. fire it up.. .. get a big aasss rubber band.,, tie the thing to a tree.. and push it backward.. doooeet
    .. lol
     
  16. exavid

    exavid New Member

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    Weight matters on a drag strip but doesn't have much effect on top speed on level ground with lots of room to accelerate. Wind resistance is the real problem. The power required to move a bike at 60mph is 8 times that needed to go 30mph. That's at steady state speeds not counting acceleration from 0 mph on a dragstrip. So you'd need even more power to get to the desired 60mph due to the limited amount of time available to achieve that speed. Whether it can be done or not is up in the air. I tend to think it could be but not with a stock China girl motor kit. Besides the work on the engine that's going to be needed the lightest chain and thinnest sprockets and perfectly mounted rear sprocket is going to be important. A chain tensioner would be a real drag and should be eliminated. A streamlined fairing aft of the engine might help. One thing that might be worth considering would be turning the piston and cylinder around and replacing the intake filter with a ram horn or simply making an air ram horn that wraps around to the carburetor in the usual location. That won't give as much boost but it would still help. Small tires and lots of pressure would also be important. The important thing here is to get the most power possible out of the engine and the least drag in the chain drive system. Gluing some shrink wrap to the bike wheels rims to smoothly cover the spokes would also reduce some drag. That's what was done on WWI aircraft that had spoked wheels. It really is an interesting challenge.
     
  17. corgi1

    corgi1 New Member

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    .........and a double walled helmet and a long sand pit at the end for stoping lol
     
  18. Creative Engineering

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    Corgi,

    Drag strips have a paved, "shut down", stretch after the 1/4 mile trap. It isn't 1/4 mile and then blam nothing!

    Jim
     
  19. exavid

    exavid New Member

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    You really don't have to worry about slowing a 60mph bicycle, it's kinda like throwing a cotton ball, once you take the power off it will slow rapidly just due to the air drag.
     
  20. corgi1

    corgi1 New Member

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    At 60 mph on a bike cotton or not theyed be sucked up so tight that I wouldn't get that much air drag lol
     
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