honda cr80 engine

Discussion in 'Motorized Bicycle General Discussion' started by squirrel, Nov 13, 2012.

  1. squirrel

    squirrel New Member

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    when i was 10-12 i rode dirtbikes, i had a kx 80 and my buddy had a cr 80. those bikes were strong for their size. they had 5 gears and were fast.
    i see lots of morini clones and ktm 50's being used on MB but why not one of these engines?
    seems it would be more reliable to have gears in the tranny instead of a jackshaft and derailleur?
    someone educate me here....am i missing something? is it the watercooling that makes it a pain? i feel like my kx was aircooled....
    i would like to put one of these engines on a 27inch road bike frame with a lightweight aluminum fairing, scary fast.
    thoughts? am i crazy?
    squirrel
     
  2. 16v4nrbrgr

    16v4nrbrgr New Member

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    They're big, and make in frame mounting hard and pedal cranks need to be chopper style to clear the case. Those are the main drawbacks, they're awesome though. People are planning stuff with them, just check around and there are builds.
     
  3. socialdistortionkid

    socialdistortionkid New Member

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    Its funny that you mention 80/85cc dirt bike engines in a motorized bike because ive been thinking about how badass that would be in a bicycle. I plan on building one in the future with a fmf fatty expansion chamber and reeds. It would wear out the sprocket and chain tensioner very quick though. It can be done.
     
  4. JonnyR

    JonnyR New Member

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    i dont see a size issue with the KX80 engine just the issue of mounting the radiator
     
  5. dragray

    dragray New Member

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    are you nuts? sure it would be bad ass, and it would be very fast.
    but, how are you going to stop it?
    bicycle brakes won't do it, so you'd have to modify motorcycle wheel drum brakes to it.(or disks).
    and then there's the quality and strength of the bicycle frame.
    bicycles were never meant to go that fast and withstand that much vibration.
    a bicycle frame would eventually fail under all that power (but it would be fun as **** up to that point....lol)
     
  6. squirrel

    squirrel New Member

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    my nickname is squirrel...so of course im nuts! haha!
    front and rear disks i think would stop it.
    ive considered the vibrations and clearances on the chain stay.
    the frame could be reinforced with steel plates that wrap around integral welds like around the head tube and bottom bracket to seat post and chain stays.
    while thinking about the radiator mounting i could only come up with two choices. one would be the underside of the down tube or in front of the handlebars...banshee style...i always thought banshees looked a little odd though.
    the other issue would be the 27inch tires...i know they make some kevlar high pressure tires for road bikes but 60+ on a 1.25 inch wide tire seems sketch!
    im no expert but i would assume a 212cc predator vibrates just as much.
    this is not a start of a build...just throwing around ideas for my second build which i will start next summer. not gonna build another china girl, i want more power!!!brnot
     
  7. squirrel

    squirrel New Member

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    sportscarpats bonneville flyer would be the ultimate!
    lol
     
  8. JonnyR

    JonnyR New Member

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    you are going to need moped or small motorcycle rims and speed rated tires like on the Bonneville flyer sportsmans world record holder
     
  9. squirrel

    squirrel New Member

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    found a complete 1987 kx80 on craigslist for 300...just needs a piston kit...
    buying a complete bike would be the way to go i think.
    that way i would get alot of the parts i would need including the hubs, brakes parts, electrical components, ect. the rims on an 80 are pretty small...19inches i think...
    tons of vintage frames on craigslist, cafe? BTR?...
    i need to finish the rebuild on my current bike and sell it before i think about this too much more, its nice to daydream though.
     

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