Carburetor relocation for Honda GX 31/35. How and who has done it?

Discussion in '4-Stroke Engines' started by alexander, Nov 17, 2009.

  1. alexander

    alexander Member

    Me again.

    One of the tricky missions i still have to complete is to relocate the carburetor on my GX 35 back towards 'sort of behind the motor' so i will get my legs past the motor better (Frame mounted).
    It would be nice if somebody has all ready done might save me some 'head sratching'.
    I was also wondering if anybody has any professional opinion about if a longer inlet pipe would make much difference in performance.
    I personally think it shouln't make much difference if any at all but i dont know for sure.
    I will of course polish the inlet pipe inside to try to make up for the longer/more friction airflow.

    A similar but not as big of a problem with the exhaust.
    I would like to totally change it but might have to settle with just extending it to start off with.
    The problem is that with a motor mounted in the frame and with the crankshaft vertically the exhaust outlet points straight upwards towards my face so the least that needs to be done is to face the outlet downwards.
    Even better to extend it past the seatpost otherwise all the noise will be in my ears instead of behind me.
    Even better to build a totally different exhaust that is quieter as long as the motor doesn't loose any power like that.
    But just to hear from somebody who has made an custom exhaust up would be great.

    My old idea from my motorcycle days was to have a valve in the exhaust that can be moved from the handle bars so that when coming into town one switches to 'quite' (if power is lost like that it wouln't matter much in town) and out of town switch back to 'nice sounding' and 'freer airflow/powerflow'.


  2. loquin

    loquin Active Member

    Curious - why do you have the crank oriented vertically?
  3. alexander

    alexander Member

    Hi 'Loquin'.

    The reason for why the crank will be oriented vertically is that i am running my bike with a Worm Drive/Reduction Box that attaches to the end and in line with the motor as in my present bike setup, see the photo below.
    Except that in my next bike the motor setup will be mounted in the 'frame triangle' meaning the present setup turned 180 degree horizontally and then 90 degree vertically so that the motor is above the reduction box and the only way it fits into the (modified) frame triangle is with the motor/crank oriented vertically.

    Attached Files:

    Last edited: Nov 18, 2009
  4. Old Bob

    Old Bob Member

  5. loquin

    loquin Active Member

    What's the reduction ratio on the worm drive? (A roto-tiller gearbox, by any chance?)
  6. alexander

    alexander Member