Big trouble on little bike

Discussion in 'Motorized Bicycle General Discussion' started by trojanmantony91, Dec 18, 2010.

  1. trojanmantony91

    trojanmantony91 New Member

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    hi, i have been wanting to mount a bike kit on my bike for a while now. My biggest question is how fast i will be able to go. I am a 330 pound power lifter and im trying to drop weight, but its going slow. i know from forums here that cops wont be able to spot an 80cc motor from a 49cc, but how fast would an 80cc make me go on flat ground? if i could hit 30 that would be nice, and up hills i have no issues pedaling, as long as the motor can do most of work(hills here are very very steep) my bike is a specialized hardrock with roadbike style tires and rock shox downhil suspension. i plan on doing basic mods from this site on it, and putting high octane fuel in it(my dad uses racing gas in his gto, sounds like it would be best bet after reading forums here).

    is this a pipe dream or possible? im a tech person so i suck at gas engines but i am willing to learn.laff
     
  2. skiball83

    skiball83 New Member

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    For one high octane gas would just take your money and probably leave you with less power, use 87 - 89. These are low compression motors, most 6:1. For what you are saying I would stay with the stock gear to be able to hit 30. BTW 30 is about the max with a 44t gear but will still have power to take some hills. You will probably see less being about 27-28. If you need to climb high hills you need to rethink your gearing and take a bit off the top end. Go to anything higher than a 44t like a 52t or somthing in between, just remember you will never hit 30 with anything less than a 44t(and thats pretty much red lining). Now on the other had if you have a bike with gears and you can spend some more cash the get a shift kit. That will let you do what ever you want. Low end, mid power, high end. BTW if your dad is putting anything over 93 octane in his GTO on a stock motor he is just emptying his wallet faster than he is hitting the quarter mile. Tuned motor thats a different story. Good luck and have fun.
     
  3. trojanmantony91

    trojanmantony91 New Member

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    thx for reply. i will look into shift kits then. no clue what my dad puts in it. but its purple and burns a lot more rich than anything ive ever smelled. leaded fuel.
     
  4. trojanmantony91

    trojanmantony91 New Member

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    prolly a stupid question, but would the shift kit on my mountain bike work? isnt it relation of tire rpm to crank rpm that matters? couldnt i just let off the gas and shift my rear wheel to a diff gear with diff teeth count and yield the result i want? or do i have to buy a shift kit seperate for the engine?
     
  5. scotto-

    scotto- Custom 4-Stroke Bike Builder

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    Welcome to the forum trojanmantony91.....where on earth do you get leaded fuel these days? Is it avgas or something?

    Yes a shift kit should serve you well, especially if you've got big hills. Don't get discouraged with the installation, you have all the help you need right here! Cheers!
     
  6. scotto-

    scotto- Custom 4-Stroke Bike Builder

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    Your motor only uses one drive sprocket with out a shift kit....the shift kit jackshafts the power over to the gear side enabling the use of those gears.
     
    #6 scotto-, Dec 18, 2010
    Last edited: Dec 18, 2010
  7. ruppster

    ruppster New Member

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    Welcome aboard, are you a fellow mainer? If you stay with a stock kit you might be disapointed if your looking for any kind of speed and hill climbing. Imagine your car with only one gear. A shift kit will give you a broad range of gears but you might want to read the requirements for a kit on the SBP site.
    If you expect it to push you along at a 20-30 mph pace on flat ground and help you up hills at much slower speeds your golden.
     
  8. trojanmantony91

    trojanmantony91 New Member

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    so the grip shifts on my mountain bike are useless then? Im from washington btw. even tho 66cc is not legal here i think im going to get one being as how im a big person and a 66cc will prolly get me to 30mph on flat ground so i can commute.
     
  9. Goat Herder

    Goat Herder Gutter Rider

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  10. breno

    breno New Member

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    shift kits are gr8 IMO for higher speed just make sure you get your gears set up well for flat shifting or near enough coz without doing that it'll sound gr8 but IMO you wont really be getting there much faster at all. 6 sprockets, 3 chains and 2 freewheels to go through and look after. If your not exactly too clued up on the whole MB buizzo you might be better off just getting the 44tooth to begin with and get used to all the nooks and crannys before making things complicated as a beginner.
     
  11. breno

    breno New Member

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  12. trojanmantony91

    trojanmantony91 New Member

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    thanks for heads up. my dad is really good with bikes, ive been 35 down hill on my bike, good wheels and brakes :) so far no broken spokes or anything. i just want to commute with it now i got a kona to play with offroad.
     
  13. trojanmantony91

    trojanmantony91 New Member

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    i made sure my wheels and breaks are ok for my weight :) my dads pretty good with all that and ive been downhill 35mph and they held up fine. now that i got a kona to play with offroad tho im interested in making this specialized my commuter bike. so nothing too crazy with it.
     
  14. breno

    breno New Member

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    You might wanna get yourself the heavy duty hub and 12 gauge spokes as the torque from the motor will shred your spokes and you'll find yourself replacing them too too often I only weigh 100kgs and this was a problem for me but then again I do punish the MB pretty hard.
     
  15. trojanmantony91

    trojanmantony91 New Member

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    ok thanks i will do that. chances are my dad put something like that on since he is crazier than me and breaks anything that isnt heavy duty. i will ask him. if the kona was lighter i would use it cuz the things meant for people who jump 20 feet in the air and crap.
     
  16. breno

    breno New Member

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    Theres a coupl of motorcross jumps near by which I like to attack here and then need a good run-up though and there is usually a bad landing to follow due to not enough speed but the HD rim holds up sweet not one buckle yet though I did locktite all the spokes otherwise they tend to rattle themselves loose.
     
  17. trojanmantony91

    trojanmantony91 New Member

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    thats brutal, i dont do jumps, at my size i cant get the speed to. the kona is just a failsafe since my dad doesnt want me to brake a frame haha
     
  18. ruppster

    ruppster New Member

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    I think breno might be onto something start with the basic kit and and build from there. That will familiarize you with how things work and the weak points will make themselves known and you can build from there.
     
  19. trojanmantony91

    trojanmantony91 New Member

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    ok ^_^ thanks for all the input guys
     

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