How to make bike faster?

Discussion in 'Forum Help & Suggestions' started by Callum2461, Jul 23, 2014.

  1. Callum2461

    Callum2461 New Member

    Hi, I have a 70cc 2 stroke motorized bike and I have done lots of repair work on it. I was just wondering how I can make it faster? A mate told me to put a bigger sprocket but I'm not too sure? Any help would be much appreciated, thanks.

  2. butre

    butre Well-Known Member

    porting and balancing if you're handy and have a die grinder or dremel. if you can weld, an expansion chamber with a properly tuned header length can work wonders.

    bigger sprocket would reduce top speed and improve acceleration, smaller would work the other way around. that's the theory anyway, in practice with a gasoline engine if you go too small you'll reduce top speed because your engine won't be able to rev as high. a stock engine can get away with a 40 tooth, but I wouldn't want any smaller than 44 if I had to deal with hills.
  3. Fabian

    Fabian Well-Known Member

    Recalibrate your speedo by entering a 29 inch wheel size. That will definitely increase your speed, and you'll be able to tell everyone how much faster your bike goes!
  4. jaguar

    jaguar Well-Known Member

    click on my signature link if you're ready for speed
  5. KCvale

    KCvale Motorized Bicycle Vendor

    I will assume the 70cc was a typo trying to type 80cc but neither exist, you have a 66cc.

    Your least expensive boost will be an NGK 5944 (BPR7HIX) Iridium spark plug for $8, that's all I run in all the 2-strokes I build (~60 so far).

    The real boost however as mentioned above is a properly tuned expansion chamber exhaust, that will give ya about an extra pony (1/2 a horse) boost.

    Though a pain in the butt to install I use the SIckBikeParts X-pipe as most of those single unit banana pipes have issues with the pedals and just don't give the boot you expect.
  6. AssembleThis

    AssembleThis Member

    Very funny.