My Go Kart

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Date Of Project: Spring 1999

Image Of Go Kart From Front

This is actually the third of a series of go karts I built. If you think the engine is the same as used on my scooter, you are right. One of the reasons for the go karts was because I got a little too big for the scooter. As I mentioned, this is number three and is officially referred to as the "SM2K". It is a small acronym for "Sewer Mobile 2000". The name came from the first unit that was built. It was about half the size of the one pictured above and ran on electricity. It was small enough in fact that it fit into the large storm drain outlets in a forest near my house. Hence the name. There were two problems with the first though. It was still too small, and way too powerful. I did not want to spend the money to build or buy a proper motor controller, so it had two speeds; off and fast. When the switch was hit, it would rapidly accelerate until it became too hard to control, at which point I would promptly flip over. And the motor was too powerful and had a tendency to rip itself off it's mountings.

So the electric drive was removed (much too my disappointment) and it was retrofitted with the engine from the scooter. Unfortunately, the small vehicle barely had enough space to hold the larger gas engine. It did work though, and I drove it around for a while. It was almost the rolling death mobile, as it was very unstable and extremely fast. Plus, there were no brakes. I decided that I better just start from scratch and build something much larger, rear wheel drive (the first were front wheel drive) and most importantly, with brakes.

Back Of Go Kart

The SM2K actually only took a weekend to build, but about two weeks to debug. I started from the back. The single back wheel was mounted, and then the gear converter was installed. There are two reasons for the gear converter. The shaft on the engine is on the wrong side, and the clutch requires a belt drive. After that the engine was mounted. This actually took some effort, as things had to line up properly and tension had to be put on the belt. I decided to use mounting slots instead of straight bolt holes so that I could adjust things as the belt stretched. It was a matter of using strong rope and a clamp to keeps things tight as I snugged down the four mounting bolts. I would later have to go through this process a few more times after I rebuilt the worn out clutch. The seat is something that anyone who has been in a public school will recognize. In fact, it was, well, liberated from my grade 12 Religion room. It was damaged anyway, and would most likely have been thrown out in a few days. The brake is a standard bike brake, but you can't see it very well in the picture The pads don't last very long and are hot enough to smoke during hard braking.

Front Of Go Kart Front Of Go Kart

The front wheels are simple lawnmower wheels from a very old lawnmower. I tried newer plastic wheels, but they just ended up melting. I did, however, have on hand a pair of metal wheels with actual ball bearings. They were installed in place of the plastic ones, and work really well. The front wheels are attached to a 4x4 which pivots on a bolt to facilitate steering. The actual control of the steering mechanism is done by two thin steel cables in standard "soapbox" fashion. The cable is wrapped around the shaft of an old pair of bike handle bars. As the shaft turns the cable is pulled, which in turn turns the front wheels. It is very insensitive steering. The handle bars must be turned a great deal to get a small movement in the front wheels, but this is good as it means that sharp turns are not accidentally made, possibly tipping the thing over. It is a lot more stable than it looks, but not as stable as a wider go kart. The controls on the handle bars as in the form of standard bike brake levers. One controls the throttle, one controls the clutch and the other applies the brake to the back wheel.

View From The Drivers Seat View From The Drivers Seat

When the basic structure was done it was time for the extras. A AM/FM/Cas stereo was installed, with a single speaker directly in front of the drivers seat. Below the speaker is the small console with the controls. From left to right: Engine kill switch, headlight/running lights, stereo. The one below the stereo switch controls the power antenna. I was tired of stopping to walk behind the engine to pull up an old TV antenna, so I picked up a power antenna out of an old Cadillac at my local scrap yard. Since my radio does not have a controller for a power antenna, it must be raised and lowered manually. But it still more convenient than actually doing it by hand. An the left side of the handle bars there is a small switch to control the turn signals, on the right is a large red button to blow the horn. The small piece of pipe beside the console holds the circuit to flash the turn signals. Power is supplied by a standard 12V car battery, which sits on charge when the SM2K is not in use. There is no alternator.

Current Features

Planned Future Improvements

Want to ride this thing? Well, sorry but I can't have everyone coming to my house to try the go kart. You can however watch a video I made of a short trip around the block. The speeds don't exceed 40KpH (to protect the camera), but it is still quite fun. You can watch the video using the Real Player available from Real Networks as a free download. Choose the version of the video below depending on your connection speed. They are both the same, except one just looks and sounds better than the other. The camera was mounted on the back about a foot from the top of my head.

Low speed version for modem users

High speed for dual ISDN, Cable modems, ect.

Frequently Asked Questions

Please read the following FAQ before emailing me about this project. It may answer your question. The FAQ is updated based on common questions I receive via email.

Are plans for the go-kart available?
No, sorry. I have not drawn up plans for the go-kart, and probably won't in the future. It is a very simple machine, and should be easy to recreate from the images shown.
Can I use a lawnmower engine?
Yes, if it is a horizontal crankshaft engine. Vertical crankshaft engines (by far the most common, with the recoil starter on the top) cannot easily be used. You could in theory use 90 degree gears to get a horizontal shaft, but the expense is probably greater then a horizontal engine. Vertical crankshaft 4 stroke engines cannot just be turned on their side as the lubrication system won't function properly. If you modify the system (replace with parts from the horizontal version), remount the carb and make a custom engine mount, you could do it. No, I do not have any plans or examples on how to do this.
Can I have more details on the "gear converter"? How do I make one?
The part I refer to as a "gear converter" is simply a 1/2" diameter jack shaft, about 8" long, with a sprocket on one end and a pulley on the other end. You can find a similar piece on lawnmowers, ride on lawnmowers, snow blowers, etc. You can make one yourself if you get a length of 1/2" keyed shaft, two "pillow mount" 1/2" bearings, and the appropriate 1/2" bore sprocket and pulley. Install one bearing at each end of the shaft, and then slip on your pulley/sprocket. Now bolt the whole mess to your base, making sure to keep the bearing fairly tight against the sprocket/pulley.
Can I have more info on your electric go-kart? What motor did you use? How did you control it? What battery did you use?
The electric kart was a smaller version of this one, with a single front wheel and rear steering. Picture this kart shortened by about 3 feet and backwards. The motor was a starter motor from a Honda Civic. A sprocket was welded to the shaft, which connected to the front wheel via bicycle chain. The battery was a standard car battery. The only control for the motor was an on-off switch. You would throw the switch, be momentarily blinded by a shower of sparks, then hold on for dear life.
Can you really put nitrous on a go-kart? Are you going to do it?
Yes, you can really put nitrous on a go-kart, you just need to use a "wet" kit and size the jet appropriately (very small). No, I am not going to do it. I have moved on to other things.
How does the steering work?
The steering "rack" is simply a length of 4x4 fence post. A bolt goes through the middle which secures it to the body of the kart. This allows the 4x4 to pivot. To control it, steel cable connects to a screw eye at each end of the 4x4. This cable is routed through two pulleys underneath, up through the body and then wraps around the shaft of the handle bars. As the handle bars are turned, the cable is pulled in on direction and slackened in the other. This pulls the steering from side to side. Look at any "soapbox racer" and you will see the same system. This is also a very poor system. Better systems are to use a steering box or rack and pinion unit from an old ride-on lawnmower or small car.
Where can I get more information and home made kart plans?
A great resource is DIY Go Karts. On the site are plans for go-karts, mini bikes and mini choppers.

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