New guy, motor question

[T3clay]

Hey guys, I'm new here and want to build a kart for my son and I in the near future, we want a cart to drive offroad on trails gravel roads campgrounds ect. My question is how big a motor would you reccomend so that we can get a decent speed and hill climbing ability.
Would a 9hp have the power?
I'm excited to start the project!!

Thank you for the help

 

[OzFab]

9hp will be plenty of power; there are loads of karts running on the 212cc, 7hp Predator engine without a problem.

As for the hill climbing aspect, I strongly suggest you use a CVT (torque converter) over a centrifugal clutch with somewhere around 6:1 - 7:1 gearing (depending on weight & tyre size).

Good luck with your project, be sure to start a build log &, of course, let us know if you have any questions

Oh & remember, there are no stupid questions...

 

[T3clay]

Thanks fabroman I did a mini bike project a few years ago and loved it, want to get back into the hobby!

 

[dnuccio]

if you dont want to spend the coin for a torque converter, you could always run a jackshaft setup with a centrifugal clutch. obviously the TC is alot better, but the jackshaft costs probably half as much depending where you buy your parts.

 

[OzFab]

A jackshaft only gives you the ability to create a lower geared system but, it's still constant. A torque converter gives you variable gearing &, therefore, the ability to climb hills while still achieving a decent top speed

 

[dnuccio]

A jackshaft only gives you the ability to create a lower geared system but, it's still constant. A torque converter gives you variable gearing &, therefore, the ability to climb hills while still achieving a decent top speed

right. i was just suggesting the jackshaft in case he didnt want to/couldnt drop the money on a torque converter.

 

[modelengineer]

If you can find a written off motorbike for cheap that'd get you more power and a manual gearbox. Depending on how old your son is that might be a better option.

I'd recommend a 250cc if he's old enough to control the power.

 

[T3clay]

What would a 250 cc cost?

 

[landuse]

What would a 250 cc cost?

That depends on a whole lot of things like location and condition of the engine. Have a look on your local craigslist for a comparison

 

[T3clay]

If I was going to put a 550 in a kart would that be too much power? Too much weight? Too much fun?

Been looking on craigslist and I see there's lots of options out there

 

[Doc Sprocket]

Really depends on the kart. You may be okay with a well-built buggy or a full-on race chassis. On a fun/yard/concession/crap kart, it's a Darwin Award waiting to happen.

 

[OzFab]

See if this answers your question

 

[T3clay]

Wow that's crazy, how difficult is it to rig up the shifting/ gears on a cart like that I have done some work on mini bikes but only with jack shaft kits never with shifting ect

 

[dnuccio]

Wow that's crazy, how difficult is it to rig up the shifting/ gears on a cart like that I have done some work on mini bikes but only with jack shaft kits never with shifting ect

just have to mount a shifter and a linkage/cable. and depending if you get a semi-auto one or not you may need to set up a clutch pedal.