Reverse Happy Time

Discussion in '2-Stroke Engines' started by Simon_A, Jul 3, 2009.

  1. Simon_A

    Simon_A Member

    I am planning to built a trike, but the design I am leaning towards means the only practical way to motorise it is to mount a happy time backwards.

    Will these motors run in reverse to their standard rotation?

  2. Just_Gasit

    Just_Gasit Member

    I believe the ignition timing will prevent it from running. Spark generally happens before top dead center and it would happen after top dead center if you spin it backwards. The timing would likely be too retarded to even run and if it did run, the power will be very low. I don't know if the timing can be changed as I haven't even recieved my first HT engine yet. I'm guessing here but it may be possible to cut a new notch for the flywheel keyway the correct amount away from the magnet on the flywheel on the other side and that will work. Like I said, I have yet to look inside one of these motors but what I said might be possible.
  3. pdxrhett

    pdxrhett Member

    If you could find a way to make these motors spin opposite direction, you sir have just beat the shift kit.
  4. Simon_A

    Simon_A Member

    Yeah, ignition timing was my main concern. I know you could get offset woodruff keys for pocketbike engines to play with the timing. Wonder if the same thing can be applied to these.

    So I would have to engineer a retarding offset key to have it advanced if running in reverse.

    I cant think of any other issues, can anyone else?

    Edit, Ignition timing might be a easy fix. Just checked the Magnet in a engine and its symetrical with a offset to set the timing. Turn it 180 degrees and it will retard the timing by exactly the amount it is advanced.

    Have a look.

    Attached Files:

    Last edited: Jul 4, 2009
  5. Just_Gasit

    Just_Gasit Member

    From what I see in the picture, the key notch is at about 11:00. You could cut another notch at 1:00 O' clock and that should give you the correct timing. If you 180 it, you will be near the bottom of the stroke, not coming up on top dead center. Does that make sense? I'm pretty sure I am correct about this.
  6. Clotho

    Clotho Member

    That still wouldn't work as a frame mount. You might be able to get that to work as a rack mount however.
  7. Simon_A

    Simon_A Member

    Sorry I wasnt clear when I said turn it 180 I meant pick it up flip it over. This puts the notch at 1 OC.

    It is to be fitted to a delta trike I am making from the ground up. Not a issue :)

    Also I dummy fitted a engine to a bike, if the carby pipe is cut so it no longer has a bend in it, the engine can be turned so the carby is straight and the chain from the output sprocket runs down to the bikes bottom bracket perfectly.

    Edit: So for a bike variant, You would still need a freewheel crank setup like sickbikeparts sell. But from there you are home and hosed.

    Veeeeery interesting
    Last edited: Jul 6, 2009