Kids' go-kart

[gman]

help .has anyone got an old nifty fifty or sim they dont want??
willing to swap beer for it!!

as normal i have no budget and my kids would really like it too....

cheers

[ManDownUnder]

Not here but I have had some luck getting an old chainsaw motor stripping it down.

Next hurdel is to put a sprocket onto it, but it comes complete with clutch etc... no gears just point and squeeze!

Also - got some really good go-kart plans but they're going to actually need a budget (and a cut off saw, welder etc etc etc).

[TonyB]

Had a gokart with a chainsaw motor when I was a kid. They work really well, though you need a decent sized one to get the required grunt. One point to remember is the noise- chainsaws aren't quiet...not so good for kids hearing long term.

[ManDownUnder]

Had a gokart with a chainsaw motor when I was a kid. They work really well, though you need a decent sized one to get the required grunt. One point to remember is the noise- chainsaws aren't quiet...not so good for kids hearing long term.

Points all noted. This one is really quiet, but then I suspect that's because it is in pieces all over my bench...

[gman]

im working in an engineering shop so welding and lathe work is no probs.

[ManDownUnder]

im working in an engineering shop so welding and lathe work is no probs.

Where are you (Where the f is bainesse). I'm a Fitter Turner (turned computer geek) and I miss things that go round and cut metal (read "mill", "lathe", "drill press" of any calibre).

I have a bunch of bits that need machining to get this cart on the road - swap you some (bloody good) plans for a spot of machining on the exles and steering gear?

MDU

[TonyB]

Points all noted. This one is really quiet, but then I suspect that's because it is in pieces all over my bench...

Have you thought about using a motor from a stepthru- like a CT90 or CT110? They have a centifugal clutch and about 4 gears (+ hi/lo ratio). You could lock it in a low gear while they're learning and then when they get bigger introduce the gears. After the gokart with the chainsaw motor we built one that had a CT90 motor- it was good for 80kph.
One other thing, make sure you get the steering geometry right- I forget the correct term for it, but the steering needs to be designed so that the inside wheel turns at a sharper angle than the outside wheel. If this isn't done they tend to understeer (or not steer at all) badly on grass which is what the second go kart we built did. Not that it was all bad, I had to learn to turn rally style by putting it sideways before I got to the corner

[ManDownUnder]

Have you thought about using a motor from a stepthru- like a CT90 or CT110?

Yup - looking at those opions for later on. Trademe has good bike engines coiming up semi regular and for $400 I can probably pick up something that'll give me a thrill on something a little bigger (like a 400cc go cart)

Steering geometry points notes. All very true and I have plans that address all that.

Cheers!
MDU

[gman]

Where are you (Where the f is bainesse). I'm a Fitter Turner (turned computer geek) and I miss things that go round and cut metal (read "mill", "lathe", "drill press" of any calibre).

I have a bunch of bits that need machining to get this cart on the road - swap you some (bloody good) plans for a spot of machining on the exles and steering gear?

MDU

dude ...Bainesse is state highway 56 between palmy and himitangi.blink and its gone!!!

our lathe at work is a bit of a shitter so as long as u dont want 40thou of the middle of a 2foot shaft its ok.
we use it to make large pins ,turn pipe down ,make square round etc..

we dont have a mill or keyway cutting (yet hehe)
let me know what ya want done and ill see if i can do it.
i love making shit at work .....just love it..

[wonder_nz]

dont know if your still looking but here is some plans for a realy good kids buggy kart http://homepages.slingshot.co.nz/~anguskarts. has cads to make chainsaw adapter sprocket you just need a lathe for a hour or 2. realy easy to make and you dont need to savage a perfectly good saw, just bolt it on

[xwhatsit]

One other thing, make sure you get the steering geometry right- I forget the correct term for it, but the steering needs to be designed so that the inside wheel turns at a sharper angle than the outside wheel. If this isn't done they tend to understeer (or not steer at all) badly on grass which is what the second go kart we built did. Not that it was all bad, I had to learn to turn rally style by putting it sideways before I got to the corner

That's called toe-out, or negative toe. You're quite right, this will massively increase the ability for the kart to turn in on loose surfaces, but in a straight line it will be a little bit unstable. One way of getting around this is to have an eccentric so that when you turn, the inside wheel always turns more than the outside -- so while the wheels are at neutral toe in a straight line, the more you turn, the more toe-out you get.

Steering geometry is very important on a kart. If you do it right, you can avoid the need for a differential (at least on grass). Rake back the steering axis, and if you faff around enough, you can get it so that when you turn, you unload the inside rear wheel by slightly lifting it off the ground -- so it will wheelspin in a corner. Not a bright idea for tarmac, of course, but in a wide-wheelbase kart designed for grass or gravel, it works quite well.

In terms of engines... yeah, a scooter one is good, with the centrifugal clutch. Gear linkages can be a pain in the arse though.