[kurt98]

This is a design i am working on for a go kart. I plan to put at least a 600cc superbike engine on. I hope to build this project but it will have to wait until after my triumph chopper project.

[Splint]

I used to be pretty friendly with a guy who built a few super karts of his own. He made a revolving jig so welding the frame would be easier. The jig had movable fixtures to allow the tubes to be located in different positions so he could make any design he wanted on the same jig. With a 600cc superbike engine you'll be the fastest thing on the track, is there such a class for racing this or is it just for fun?

Splint

[Splint]

Just some of comments on the design, you might want to consider running without the cross brace under the seat as you will need to get the bottom of the seat about 1" off the ground otherwise it may get too top heavy. Another thing is you might want to consider running a pair of inboard chassis rails from the inboard axle bearings which run parallel with the outboard rails and then merge into the outboard rails approaching the waist line of the frame, or use one u shaped rail which runs from the inboard axle bearings and across the front of the seat, this could have bolt together, rubber insulated stays which join the inner and outer frame near the waist line which would be adjustable to control torsional stiffness of the frame. Also, most modern karts have frames that start to taper in to the waist line much further rearward than your design. You may also want to run a torsion blade across the rear of the frame, turn the blade virticle for max rigidity or flat or removed for max flex.

Splint

[RICHARD ZASTROW]

kurt98, Is that a 600cc 2-stroke (GOD HELP YOU) or a 4-stroke? In race trim a 600cc 2-stroker can push over 200 hp. Scary!!

[kurt98]

The motor will be a 4 stroke engine off a wrecked crotch rocket. The point made about seat height is a very good point i will get rid of those cross members.

[Switcher]

Maybe add a full roll-cage, air-bags, & a paramedic on standby?

Dude thats going to hurt like a mofo, If you wreak!

Good luck.




.

[kurt98]

A roll cage would add to much weight. When you go and buy a $200,000 lambo you pay a little for going fast and a lot for safety. They have high safety coefficient. Since i do not have the money i am throwing safety concerns out the door. The lower the safety coefficient the cheaper the project. No I am concerned with safety but i want a crazy power to weight ratio.

[kurt98]

I made some improvements to the frame. Are there any other suggestions for my design.

[CNC Darren]

Not to get off topic but i have to add this. check out the multimedia section... www.turbokart.com

crotch rocket engine on a gokart.... cool
Jet turbine on a kart.... insane

note: the jet is not thrust only, it is tied to the wheels via a transmition.

I'm not connected with these guys at all but i wouldnt mind playing with some of thier toys lol

Darren

[Splint]

Kurt,
have you measured up the engine to see how much space is required to make it all work? 250cc karts frequently run the driver offset to one side and the motor on the other side as there isn't enough space to mount the motor behind the driver. Mounting the motor behind the driver makes the frame excessively long which makes the handling less responsive. See the pink Thundermaker frame for an example of an offset frame.
If you think you can go with a conventional frame, take a few design ideas from the blue frame, it's a very conventional, common design and well proven to work on the track. These days the design differences between the different frames is so subtle that you should be able to copy pretty much any modern frame and end up with a pretty good kart.

Splint

[CNC Pro]

I enjoy visiting nearby Watkins Glenn raceway to watch the Kart races. If memory serves me correctly, they ran a 500cc shifter-kart class that might give you some ideas for your design. Also, there is a “super–kart” class very popular in Europe as wells as in the US.

If you’re designing a one-off kart (not intended to meet certain class specifications) but instead as a fun personal project. There are many individuals & companies building mini-sand rails that run engines up to and including the Suzuki Hayabusa 1300cc engine (even with turbo’s)! There is even a company now which produces a mini version of VW’s type 1 transaxle for just such an application.

[RICHARD ZASTROW]

Trouble is thats way beyond "gokart" classification. There you're into SCCA formula size stuff. It's still fun though. Do me one favor though, WEAR LEATHERS.
CNCPro, I live near ROAD AMERICA, they added a kart track in addition to the 4 1/2 mile road course. Lotsa good stuff.

[fyffe555]

Kurt, you might want to reconsider the bracing across the frame between the curved front rails. Karts chassis are waisted between front wheels and driver to give a degree of suspension, or controlled flex to the chassis, not to give wheel clearance. That's the only compiance you get apart from tyre sidewall flex. The way you have it you'd lock the front end tight and loose the benefit of curved raills. It won't handle well. If you use the braces as shown you might as well have straight side rails, and you're building in a stress point right at the joint...

the others add good comments too. positioning the masses, ie driver location, enigne etc is important to make the thing drive straight and go round corners.

The second rail on the drive side is imortant as is a spreader across the back as close to the axle mounts as is reasonable. I used to build and drive 250 nationals in the 80's. 'Only' about 75hp but over 160mph and we would regularly bend rear frames on short tracks if we made the frame too light and not brace for thrust and twist from the drive.

You might want to be thinking about front brakes as well as a rear,,,

Andrew

[kurt98]

This project is still in the future so i do not have the engine yet. I do not know how much a motor from a 600cc or 1000cc bike weighs. But i think that there weight will throw out all chances for handling. With how much weight the engines weighs I do not want the chassis flexing. That is just what i think but i am not an engineer so correct me if I am wrong. I am not going to be building this kart to any specs it is just for fun.

[RICHARD ZASTROW]

kurt, you might want to talk to sme of those super kart folks. a little controlled flex might actually help. SCCA formula 440 is very similar to a gokart. They allow only a 2" rubber disc in the rear and nothing in the front for suspension, if my memory serves. As far as power/weight considerations, I'd look into the big snowmobile motors. I think you can get 1100cc reed valve 3-cylinder 2-strokers. You won't get as much power in warm (relatively) air as in the cold air (dense, lots of oxygen) that snowmobiles run in. They don't weigh much but thet do put out power.

[kurt98]

I got ride of the front cross brace. Do you think i should get ride of the cross brace supporting the steering shaft? All the suggestions have been very helpful. I hope the suggestions keep coming.

[Splint]

Kurt,
I wouldn't go any larger than 600cc. With 600cc you should be able to easily break traction, and once you break traction by about 25% any further break of traction will actually result in slower acceleration and excessive tyre wear. Also a larger engine means more weight (not to mention more space and the need to run a larger fuel tank) which results in faster tyre wear and possbly a less nimble kart.
I think because of the "experimental" approach to the design and so many unknowns, you should have some pretty substantial leeway for adjustment of flex in the frame, keeping in mind that getting a kart handling well is a critical part of karting. In the picture below there is a tube directly to the left of where the seat goes, this tube is removable. There is also a short chrome tube at the rear of the kart which can be removed from the kart to make the frame more flexible. Some karts have a tube which has been pressed flat in the middle to give it a blade effect, simply change the orientation of the blade to change the rigidity, or remove the blade altogether. I have also seen variations of the blade principal used in the front end of karts in east-west and north-south applications.

Splint

[kurt98]

Splint I think your have some good points about engine size. I think i will go with a 600 because it has good power and is much lighter than a 1000. In this application minimum weight is the goal.

[NEATman]

http://video.google.com/videoplay?do...c+gocart&hl=en
http://video.google.com/videoplay?do...c+gocart&hl=en

I think 1000cc's is a bit overkill - Look at the video's above.

I'm also thinking of making a gocart, but it will have full suspension for offroad capability. I'm planning on a snowmobile engine, and I'd like to make it along the lines of this:
http://www.ridgerunner.biz/

Good luck with your project!

NEATman

[RICHARD ZASTROW]

kurt, That reference to an 1100cc snowmobile engine was a bit of tongue in cheeck humor. Those things are are capable of so much horsepower IN RACE TRIM a gokart could not handle it. Seriously, I would look into a Rotax 2-cylinder 2-stroke engine. There's a lot of stuff available for them. They're used in snowmobiles, motorcycles, ultralight aircraft, jetskis, quarter midget and SCCA formula race cars. They develop anywhere from 55 to 170+ hp. As noted above, a lot of power is great. However, too much power is not only unneccessary but causes loss of control. (IMHO is stupid). I used to race when I was a little older than you are now. When I got a car with basicly too much power, I ended up off the track more than on. The fastest lap times were turned in by the best handling cars, not the most powerful. Again, Good Luck.