Need help on my motorized bike

Discussion in 'General Questions' started by Shergernetic, Jan 1, 2012.

  1. Shergernetic

    Shergernetic New Member

    Need help on my bike it won't run

    Hi guys I have a motorized bike that I've build but it doesn't run right I got my gear ratio wrong and I need your help I'm planning to use a jack shaft but don't know what size of sprocket to use so please help me out
    Motor is a 3hp
    Clutch is 11t #41
    Bottom sprocket (right side) is 44t
    Bottom sprocket (left side) 28t
    Sprockets on rear wheel 28t to 14t the wheel is 2 feet tall
    It weights about 40lbs I'm at 210lbs

    Here's a video

    Motor and bottom sprocket (right side jack shaft)
    Bottom sprocket(left side jack shaft) to rear sprocket
    On this picture the right is the motor side left side goes to the rear wheel

  2. Shergernetic

    Shergernetic New Member

    type down on YouTube
    Need help motorized bike
  3. loquin

    loquin Active Member

    At the rear axle, you should be spinning no more than about 420 rpm. W a 24 inch wheel to be running at 30 mph.

    You don't. Mention the engine rpm, but I'm assuming apx 3600 rpm max, so the total reduction should be about 3600/420, or apx. 8.6:1

    The first stage reduction is 44/11, or, 4:1. You would need an additional 2.15:1 reduction... with a 28T sprocket at the front, you would need a 60T sprocket at the rear axle... if you could swap the 14T and 28T sprockets, you'd be close...

    Btw. By removing the pedals, you haven't got a bicycle most states, it'd be considered an unlicensed motorcycle.
    Last edited: Jan 8, 2012
  4. motorpsycho

    motorpsycho Active Member

    how in the h*ll do you ride that thing with the engine right in your chest?
    I personally would not trust that frame with the amount of weight you're putting on it.
    The tubes are VERY thin.
  5. Mud Pie

    Mud Pie New Member

    Additionally, with no pedals, where do you rest your feet ?

    And with the engine right on your chest, it should make a backfire....interesting, not to mention the heat generated.

    But I will give you kudos for trying something so far from the norm.
  6. Sgt. Howard

    Sgt. Howard Member

    I'm thinking the proximity of a running 3 pony engine to my canastas would be of greater concern than my chest... a burn scar on my chest can turn into a fantastic story with full bragging rights while a fried set of canastas .... has no social value whatsoever. That's a valve cover right off the point of the seat, right? Wear a cup...
    the Old Sgt. :army:
  7. motorpsycho

    motorpsycho Active Member

    not only that, but imagine what will happen when that drive chain comes off at 3600+ rpms. it'll be like a huge steel whip headed right at your head, arms, face, etc.
    this thing just looks unsafe as all get out to me.
    I've done some pretty crazy things in my life, but i would never ride this thing.
  8. Shergernetic

    Shergernetic New Member

    Wow I've never thought of all that lol I just I'll trash it and start over again but thanks guys for the help