Torque?

Discussion in '4-Stroke Engines' started by wm_carter, Aug 16, 2010.

  1. wm_carter

    wm_carter New Member

    I'm mounting a Honda 3.5 hp 144cc 4-cycle engine on a chopper frame. I was wondering how much torque these engines have compared to the ones comenly used here in this forum (80cc) that have a lot more rpm verses 3600rpm? I'm tring to figure out what gearing set up to try. I will have a max torque 10t centrifugal clutch up front and then I am thinking of a 32t or a 56t rear sprocket, turning a 20" wheel.

    What do you guys think?

    Thanks
     

  2. tjs323626

    tjs323626 Member

    I would start with a 10 to 1 gear ratio. I built one with the HF 2.5HP using a 20" wheel and 50 tooth sprocket. I disabled the governor and got about 40MPH at a bit over 5000RPM. I used a jackshaft for a 2 to 1 reduction then a 10 tooth to power the 50 on the wheel. Your engine will have more power then the 2.5 so YMMV, but that would be where I would start.

    Good luck, and do keep us posted.

    Tom
     
  3. professor

    professor Active Member

    The only bugaboo with the 3600 rpm engine is lack of rpm range.
    You do have a lot of torque but you still need to gear the thing so it will not burn the clutch on take off.
    I think even the 56 is not big enough. After all, that is 5.6 to one, double that number for a start is my guess.
    I am using a HF with a similar rpm and when I went to a 3 speed hub in the engine driveline, it became a new machine. So, I suggest using a jackshaft of some sort.
     
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