Off Road dirt bike engined go kart. PLease help

[=SMITH=]

Today i purchased a two seater old yard kart style frame and i have a 125cc 4 speed manual motor i am putting on it. and i also have a old set of 33x13.50x16 super swamper truck tires i want to put on for one just to use them and second cause i think it would just be cool too see a dirt bike engined go kart lifted to your belly button with truck tires. So heres where the probablems start lol Does anyone have any ideas as to how to get a 16in. rim on a go kart? maybe 4wheeler hubs? or adapters?? and also its NOT live axle so how could i change it to posi? Any ideas or imputs would really help. Thanks guys Also i need to mention that i will be choopin the frame up to make it longer and wider because im 6ft. and with the frame like it is just isnt gonna work. also anybody know where i can get about a 90 tooth sprocket for a 420 or 428 chain???

 

[1992suburban]

wow.. good luck with the build


POST PICS

 

[modelengineer]

Defs post pics. Sounds like a cool project.

Any particular reason you want the big wheels? A kart that high up is going to be way unstable (unless the actual frame is close to the ground and the axles are higher than the frame, or if it's really wide)

 

[Kaptain Krunch]

That engine might have trouble turning such big tires, don't expect a whole lot of speed. Also why a 90t sprocket? Seems way to big, you might want to go a few teeth above the stock rear sprocket on the bike but that's it.

 

[modelengineer]

That engine might have trouble turning such big tires, don't expect a whole lot of speed. Also why a 90t sprocket?

I think the 90t sprocket is to compensate for the large tyre diameter. That way he will have good speed and acceleration.

 

[dpaxson]

i would recommend a jack shaft instead of a 90 tooth sprocket. also you might want to try to find a 420 sprocket that fits the output shaft of the engine. then you can use #40 sprockets which are really easy to find.

 

[Rickracer]

Just the tires and wheels will weigh more than most complete karts with the driver in them. 125 ccs isn't gonna cut it on a kart that big and heavy. If you're serious about the big tires and wheels, you gonna need a regular automotive type rear axle and a LOT more power.

 

[Carlman]

http://www.xtrememowermayhem.com/monstermowers.htm these guys have it down packed with the big wheel idea

 

[=SMITH=]

Hey thanks for all the replys guys, And thanks carlman that website really helped out. they are using a hub that slips over the spindle shaft. im trying to talk to them and see exactly what there set up is but it looks like im gonna try what there doing as far as being able to bolt rims up with the tires.

 

[=SMITH=]

dpaxson what exactly is a jack shaft? i guess im not familer with it.

 

[=SMITH=]

This is where i got a 90 tooth size sprocket from. This is a 90cc that came with alittle bigger than go kart tires on it and now has 31s. Im working on getting some pics up of what im starting with. i still need rims but i have to figure out the hub situation first because of the bolt pattern.

 

[=SMITH=]

o and this 125cc is a port and polished with a 4 speed manual. the casing is a honda crf 50 so its light weight and haus ***

 

[newrider3]

You don't need something that hauls ***, you need something with nuts torque.

 

[Kenny_McCormic]

Maybe get the rear axle out of a AWD subaru or some other small car with driven rear tires?

 

[Kaptain Krunch]

Ok I was thinking dirt bike tires which would be around 24-26" diameter and going from that to 33s wouldn't call for a 90t sprocket. But I still say you need a more powerful engine to power such a heavy set of tires, especially if you use a car rear end.

 

[Kenny_McCormic]

Nah, just gear it to crawl in first and it should be alright.

 

[Kaptain Krunch]

Yea with a top speed of 40 it wouldn't be worth it. Especially when your redlining just to get there, plus shifting that much would suck.

 

[modelengineer]

Just put normal tyres on it. It will be better in every way, not to mention cheaper and easier to make.

 

[dpaxson]

a jack shaft is an internediate sprocket reduction shaft. it allows you to use a smaller sprocket on the axle. you have a small sprocket going to a bigger sprocket on an independent shaft with a smaller sprocket on the other end. this smaller sprocket is attached to a larger sprocket on the axle. you multiply the two ratios together to find the final drive ratio. so instead of having a 10 tooth clutch and 90 tooth axle sprocket you could have a 10 to a 30 and then another 10 to a 30 on the axle giving the same ratio.

 

[=SMITH=]

Hey that jackshaft idea sounds pretty good. if i did that i wouldnt lose as much ground clearnce with a 90tooth sprocket hanging down to get snagged on things. A jack shaft setups used on go karts? Or do you just make your own?