gear ratio

Discussion in 'Transmission / Drivetrain' started by robert baving, Jul 18, 2016.

  1. robert baving

    robert baving New Member

    Trying to figure out my gear ratio. 10T clutch sprocket, 17T jackshaft in, 11T jackshaft out, and 16T axle. With 20" rear wheel

    Attached Files:

  2. CrazyDan

    CrazyDan Active Member

    According to that's 2.473:1 but those 2 smokers have internal gear reduction already, so multiply that by 2.473.

    Edit: searched the forums, internal ratio is 4.1:1. So your full reduction is 10.1393:1. Think you need a bit more reduction than that.
    Last edited: Jul 18, 2016
  3. robert baving

    robert baving New Member

    So what should be changed. Jackshaft sprocket or axle. And which way more or less teeth.
  4. CrazyDan

    CrazyDan Active Member

    With your current setup you should see about 53 mph at 9000 rpm, 29 mph at 5000 rpm. What top and cruising speeds are you looking for? Are you doing hills? Also what's the peak rpms you are seeing?

    The stock left rag sprocket with the 44 tooth coming from the 10 tooth does 4.4 additional reduction totalling 18.04:1 with the internal reduction. This is all based off someone in another thread saying your 2 smoker has 4.1:1 internal reduction.

    You can increase your rear sprocket or jackshaft input, or decrease your engine output or jackshaft output to get better takeoff/hill climbing capability.
    Last edited: Jul 18, 2016
  5. robert baving

    robert baving New Member

    Not sure of peak rpm. Looking to be able to cruise smoothly at 20-30 mph. Not dealing with a lot of hills. But with 20T axle I could go up a hill with 12% grad and still pick up speed on the way up. It's the GT80 4.5 hp engine from Gasbikes. Guess I should invest in a tach.