[Kartbuilding] Gear ratio

[Stephen Burke]

Hi John,

I have used a very similar Honda GX engine. See:
http://www.kartbuilding.net/gallery/v/Kart_Clearance_and_Memories/DSC00988.JPG.html

Without gears that Honda engine will only propel a kart up to approx. 
30mph, and thats with a slow take-off speed.
Typically, you would want at least a 6:1 gear ratio. 14" (inch) diameter 
wheels are quite large.

If your looking to use *only* the gearbox out of the Kawasaki and attach 
it to the Honda engine, I would advise against it, unless you have a lot 
of spare time, you like tinkering, and if its only for a test. I attached 
a Honda 90 gearbox (4 gears and a manual clutch) to a Honda GX engine. It 
worked, but it was not reliable with two chains turning at high speeds, 
and a large cumulative weight! (gearboxes are heavy). It was a good 
challenge, but looking back, I would have saved myself a lot of time and 
money if I had bought a complete motorbike engine.

I hope this information helps.

Best of Luck,
-steve

On Sun, 18 Nov 2007, John Parsons wrote:
> To whom it may concern,
> I am recently after visting your site and find it very imformative, I am building my own go- kart and am unsure of a few things that maybe you can help to rectify;
> What gear ratio would be required for a Honda GX 390 with rpm of 3600? (driving 14' wheels)
> Would ripping the gearbox out of Kawasaki GPZ 750 be a wise adventure, considering it is shaft driven to gear mounted in the back wheel?
>
> Any response would be greatfully appciatated,
>
> Yours Faithfully,
> John Parsons
> _________________________________________________________________