Need help building my off road go kart.

[elonmusksbigfan69]

Hello. Im a new user, that has been thinking about building a go kart. I want an off road kart, with suspension, and a 250cc 5-speed manual pit bike motor. Or a 750cc cross kart, just raised. Since its normal here to have 10cm rocks. Im thinking about the frame being from 40mm aluminium tubing. If you have any recommendation, just message me. Thank you for your ideas.

 

[madprofessor]

What's the 4" rocks about? Why 1.6" tubing? Need to choose powerplant before deciding on frame, 250/750 have different needs.

 

[elonmusksbigfan69]

What's the 4" rocks about? Why 1.6" tubing? Need to choose powerplant before deciding on frame, 250/750 have different needs.

Im just worried ill pop my tires, or damage my underside. Im not too sure on the motor, we here mainly got rocks, loose dirt, gravel and that's it.

 

[madprofessor]

Can you weld aluminum? Can you cut near-perfect copes and fishmouths in it? Can you afford the higher costs over using steel?
My last bike was a 650, and it would do 120mph on asphalt. How fast do you want to go with that 750? Gear ratios can trade off high end speed for end low torque if that's more what you want, something that will do doughnuts in a parking lot.

 

[elonmusksbigfan69]

I could learn how to weld, but i have 2 people that can weld the frame for me. I dont know what copes and fishmounts mean, but the 2 people can cut near perfect. I mean, i could use Steel but im just not sure if the 250 would handle the weight. Im thinking the frame would weight around 100kg the frame. The 250 has 18hp, and 20ft-lbs of torque. If i could i dont even wanna go like supa fast on asphalt. I just like off-roading more than speed. But 50 mph on asphalt is more then enough. Also, i forgot to mension this, but my budget is 2500$, the 250 costs around 550$.

 

[madprofessor]

Just checked out that Cars and Cameras video of the 750 Stormtrooper. Took them 4 months and $4,000 to do it, and they're basically pros at it. That certainly blows the $2500 budget, and 18 hp. for the 250 should be plenty enough to wrap you around a tree.
I think you would never regret getting a $110 house current Ironton stick welder from Northern Tool and watching some weld videos to learn it. It's basically the same one I got from them made by Klutch. You can make a kart out of round or square steel tubing and weld it all yourself.
BTW: A cope is a rounded cut through a round tube (made with a hole saw) to join that cut end smoothly to the side of another round tube, making contact all the way around. A fishmouth is a more complicated compound cut.
Here's what overweight kart means: My 520 lb. kart with a Predator 212 hotrodded up to 15+ hp., but unable to get up to the high rpm's where all the horsepower is. A 250cc dirtbike motor will easily launch a one-seater gokart, even a two-seater if not extremely overbuilt like mine.

 

[elonmusksbigfan69]

Since im just a newbie to the sport, what size tubing would you recommend? Should it be steel or aluminium? We can talk somewhere else if you wanna.

 

[madprofessor]

Nowhere else, this is really the forum you need to be on, lots of experienced and smart people on here who enjoy helping with builds.
BTW: There are no stupid questions, that's the way people learn stuff.
Welding aluminum is for experienced and properly taught welders, you need to start learning on steel. Round tubes require the cuts described above, and that's harder than the straight cuts required on square tubing. For a new welder/builder the square tube is much easier.
Most square tube builders use 1" tubing for single-seater karts. My current absurdly overweight kart got built with 11 gauge 1.5" tube, nobody needs tubing that big and heavy. Look online for free gokart plans and how to build at KartFab, or to buy at SpiderCarts to name a couple.
Go Kart Plans | Download Free PDF - KartFab.com
Go Kart Plans and Blueprints by SpiderCarts

 

[Bansil]

Before metal recommendation, what country?

I know here I throw out terms like 1-1/2 dia x .12 wall erw tube, or 14 ga 1 x 3 tube etc or 1/8 wall 1 in diameter or even .083 wall.

Notching isn't as hard as folks think, it gives a nice full penetration weld with strong base metal...



Good start


keep us posted

 

[madprofessor]

I dont know what copes and fishmounts mean

Great picture for him, Bansil. See the 90 degree joint that's already welded? That's a cope fit. See the 45 degree compound joint that's not welded yet? That's a fishmouth fit.

 

[elonmusksbigfan69]

Before metal recommendation, what country?

I know here I throw out terms like 1-1/2 dia x .12 wall erw tube, or 14 ga 1 x 3 tube etc or 1/8 wall 1 in diameter or even .083 wall.

Notching isn't as hard as folks think, it gives a nice full penetration weld with strong base metal...

View attachment 127751

Good start


keep us posted

Im from Czech Republic. My dad works at a company, they do metal and more things. I could probably get some scraps, or get new metal. They also have so many great welders, he knows all the people, and he could probably agree with the guys that weld, to do the frame.

 

[elonmusksbigfan69]

Sorry, I didnt reply yesterday, i have school, and im not that much on the phone.