Buy something that is cheap and running. Get the kid fired up. Show him how to do the maintainence/grunt work. (And make sure that he does it, have him keep a log.)
If he is still interested after he understands the work needed to run a competitive race effort, morph it into a "Let's build a better cart, with all the stuff we have learned."
Have FUN!
Rog
forget the kid - start buttering up the F-I-L............
I know the existing kart way would be faster and easier, but again, the build is half the point here. This was my FIL's idea, he offered to help us do this using his shop. Who's going to turn that down? 
Good info, keep it coming!
Tom, you are right that the build is half the point, maybe more. There is so much instant gratification these days, and for my kids, having to plan, build, find out the plan wasn't working, etc., taught them a lot about fabrication, project management, patience, and more. It also made them much more respectful with the karts when they were done--they knew how much work went into them.
We have bought a few craigslist karts for cheap ($35-100), usually with something broken. The kids fixed them, ran them for a little while, and then sold them again, sometimes for a profit, sometimes not (although they always expected a profit!). More skills learned.
Carl
In reply to Carl Heideman:
I started to read your post, but it was too long so I quit.
Cycle cart at 13; $300.
Taking the drivers ed test in a self built Locost at 16,
Priceless
www.diygokarts.com if you haven't been there already. I started my autox kart build with an existing frame and there is a lot of helpful posts and info there. We just bolted parts on but my son and I still learned a lot. Over the winter we're going to do some mods to the HF engine and fabricate new nerf bars. www.oldminibikes.com has good info on small engines, controls, gearing, etc.
We have started a class based around the HF 212cc Predator and those things can be made to move quickly with little cash investment. For more umph there is an 11hp and 13hp version.
While I would go along with doing a complete build, the boy is 13. You aren't going to have his attention much longer.
chrispy wrote: www.diygokarts.com if you haven't been there already. I started my autox kart build with an existing frame and there is a lot of helpful posts and info there. We just bolted parts on but my son and I still learned a lot. Over the winter we're going to do some mods to the HF engine and fabricate new nerf bars. www.oldminibikes.com has good info on small engines, controls, gearing, etc. We have started a class based around the HF 212cc Predator and those things can be made to move quickly with little cash investment. For more umph there is an 11hp and 13hp version.
Excellent, bookmarked!
I think I'll start working on a simple frame design in CAD, see what I can come up with. I need the practice anyhow, I haven't been on the tube in a few years.
If you want dimensions to replicate a 64 Dart kart frame, let me know. I've got one in the garage. It's a pretty basic design compared to today's stuff. You can hang 2 engines off it though :p
In reply to Tom_Spangler :
How to rebuild
a gokart
By Jakub Nowicki
Restoring a Gokart or any other basic, mechanical vehicle is difficult with no experience. There are many unexpected challenges that make your life more difficult along the way. I have learned this during the last 6 months of working on my project. I will try to guide you through your process of restoring in 4 parts: preparation, disassembly, replacing and assembly. The goal of this tutorial is to prepare you for the problems you didn’t expect, and minimize the time wasted on them.
1 Preparation
1.1 Choosing the right gokart
There are different types of gokarts, all built with different intentions and for different purposes. Here, I will not speak about professional racing karts or off road buggies but rather, old racing gokarts, meant purely for fun. There is a surprisingly big amount of these to buy online. Wherever you go, whether it’s OLX or Craigslist, you will find a surprisingly big amount of vintage racing karts that usually cost less than 250$ or 1000zł. Another place to buy these types of machines is to get in contact with someone getting out of professional karting. These people are also a good place to look for parts like tires, as professional karting takes a lot of these. Once you find the gokart you are interested in, it’s time to check its condition. The obvious thing is making sure the engine works. The other thing you would want to know is if the frame or back axle has any cracks or bends. Cracks can often lead to the frame breaking which can result in a big accident while driving. It is also crucial to know if replacing the brakes will be needed. Once you have checked that, check if the bearings work well and if you can spot any parts that are loose. The one component that you really want to focus on, is the steering column that takes the biggest amounts of force when cornering. It, having any flaws, could result in snapping, and losing control at a high speed.
1.2 Workplace
To start the project, you need to have a space to work on it. Around 15 square meters of surface you are not scared of destroying are needed to work comfortably. This space will mostly serve as a warehouse for the disassembled parts and frame, but it should also have a table for cleaning parts and taking care of the smaller ones such as the brake system. The area you will be working in also needs good lighting, around 400 lumens per square meter.
1.3 Tools
You can’t start doing anything without the proper tools. The two main pieces of equipment you are going to be using, is a regular brushless drill and an impact wrench. There is a huge difference between these two devices. Unlike the drill that needs to get momentum in order to unscrew a screw, the impact wrench delivers the power immediately with rapid hits. You should do fine with the impact wrench with 400 nm of force. To be able to use an impact wrench, you should get a decent quality wrench box (if the quality will be insufficient, the wrenches could break while trying to unscrew some parts). If you plan on using a brushless drill, get yourself a set of bits. Apart from these, a set of open-end wrenches and a drill brush are necessities. You need to remember that while buying, think about whether the size of the impact wrench adapter is the same as the size of the wrenches themselves (usually ½ inch)
2 Disassembly
2.1 Main parts
The most important thing to remember while taking apart, is to document where everything was originally. You should do it by making detailed pictures with your phone that you will use later on. I recommend starting your disassembly with the biggest parts, such as the seat, steering wheel and wheels that you will likely face problems with. To remove the tyre from the wheel you need a lot of force, which you most likely lack at your workplace. Therefore I recommend taking the wheels to the closest vulcanizer who should take care of them in about 15 minutes. The disassembled parts and screws should be kept in boxes by categories such as steering system, engine attachment or seat to keep track of where components are going. There are also several parts that are covered in grease and rust, and don’t want to move. While dealing with them I used WD-40 and a rubber hammer.
2.2 Back axle
The back axle will be another challenge. It is heavily based on being kept together by pressure. The main pressure suppliers are the two bearings stuck on the axle itself. You don’t have to replace them, but it is a thing I highly recommend doing if you want better performance. I tried treating them with a hammer which didn’t go well. The effects I ended up with were very small and the axle was damaged. To remove the bearings, you need to go to a car shop which has a special tool for that. The tool works on incredibly high pressure and will do its job with no problem. Now your go kart should be in pieces.
3 Replacing
3.1 Brakes
The brakes are the only part of the gokart that actually keep you safe, and that’s why they are crucial to the build. The type of brakes you will most likely encounter are hydraulic brakes. The common problem for this type of brake is the piston getting stuck because of being old. To get the piston out, I connected a bicycle pump, and just pushed it once. If you want to remove the pistons this way, be careful since the pistons can jump out of the cylinder with a high velocity. I suggest you take the brakes apart and clean them. The parts that will need replacing for your safety are the lines. The lines are working on 800psi, to 2000psi in the case of maximum effort, so when you buy one, choose one with over 2000. After several years of being used they are pretty vulnerable for cracking which is undesired at high speeds. To replace a part like this you just take it to a hydraulic shop and order a new one of the same size. When you put it all back together, remember to add brake fluid, not water or any other substance. You can get brake fluid on pretty much any gas station.
3.2 Sanding
You will surely want to make your gokart look like it’s brand new, and the first step to doing that is sanding. Sanding is a process of blasting small pieces of material (usually glass) on the old and dirty surfaces to remove the unnecessary coat and get the parts ready for painting. You want to sand only the major pieces made of metal like the steering system or frame, not the smaller ones like screws. One more important thing to remember is not to treat moving pieces that are in constant friction with other elements with sand. Doing that can result in destroying the parts and having to get new ones. I was pretty lucky to have a sandblaster that I had access to personally, however, most people don't, so I advise you to give the parts away to a professional who will take care of it. This will spare you time but cost you some money. It’s important to note that sanding is not a necessity. If you don't have equipment for it, you can use method 3.3 which will be much more time consuming.
3.3 Using the brush
There are some parts that you don't really want to sand. Using a wire brush compatible with your drill, will clean heavily painted parts and will produce a really cool looking effect of brushed steel. You will not want to paint all surfaces because the paint easily comes off in areas that are often hit, like the floor, rims or back axle.
3.4 Painting
To make your project look ideal, you have to customize it by painting it. This is the part in which I committed the biggest mistake because of using the wrong paints and painting parts I shouldn’t have. The effect is still satisfying but once the paint is scratched, it goes off. It is a process that cost me a lot of time and money. Therefore, If you are not a big fan of spending time doing a continuous and boring job, it can be painted by a professional. The amount of financial resources I invested in paints would be similar if I had given it to be painted. If you are willing to do it by yourself, the first thing you should think of is the paint you want to use. Regardless of the color you should use automotive spray paint you can buy anywhere online. The paint should be applied from around 20cm, in a quick way, making thin layers. At least 3 coats of paint are needed to bring the desired effect. You ought to use a primer beforehand to add a layer of depth to the paint. Depending on whether you use light or dark colors, you would want to choose a light or dark primer. You need to know that if you wait >7 days after sanding, the metal might start getting a ginger color, which doesn't really disturb the paints, but can damage the metal to some extent. The only parts that should be painted are the ones that don't move. Paining any bearing mounted in the chassis will create huge problems while steering, and you will likely have to replace them.
3.5 Blackening the bolts
If you wish to make your bolts black, and make them look fresh, a bit of chemistry is needed. The first step is to wire brush them. You can also use a sandblaster if you are looking for a more matte finish. The next step is making a black oxide concentrate and distilled water mixture in the proportion of 9 (boc) to 1 (dw). The concentrate you can buy online and to
distill the water, you just boil it. After keeping the bolts in the mixture for about 20 seconds, you ought to dry them and put in distilled water. To add an extra layer of protection, applying WD-40 and waiting for it to soak in will help. It is important not to paint the bolts and nuts, as then, you will face problems while trying to screw them in.
3.6 Engine
Unfortunately, there is not enough space on a 100 pages that could tell you how to repair your engine. The first thing to do is check these 3 most crucial elements: fuel injection, spark plug and air intake. These are the 3 pillars of any working engine, so if any one of these fails to work, just find a way to replace it. Watch out when testing if the spark plug works- it may surprise you with a few volts in your body, so always wear a rubber glove. You ideally buy one that already works, but if it doesn't, you have to look for problems with your particular model online. That’s what I did, and I found that a typical flaw of 147FMF engines is the parts getting loose, because they came from cross bikes which jump a lot. I stripped apart the whole ignition chamber and a big part of the cylinder. While putting it all back together I did my best to assemble the parts as tightly as possible. Unfortunately, that still didn't help, and so I asked a person who knows a lot about engines for help. It turned out that the ignition was not connected ideally to the rest of the motor, and that was why it didn’t want to start. It is really difficult to make an engine run with no experience in this field. You can also buy new engines for your gokart. It doesn't have to be a shifter kart, it can also have a torque converter and no gears. This type does not have the greatest performance, but it delivers enough fun, and is much simpler due to having no gears. If you are looking for something like this, the Predator 212cc and its Honda rival make up for best choices. These 212cc engines however, are difficult to get in Poland. An option that is much easier to acquire is a motor from any motorcycle. The cheapest one available in Poland is WKS125, which is also extremely easy to disassemble and assemble with no experience. I don’t recommend trying out engines from street bikes and naked bikes, as these will most likely kill you, and even with a good amount of experience, you will never be able to extract all of their 100hp.
3.7 Gear shifter
There are often problems with the gear changer being too loose. Often people use the wrong parts to connect the shifter to the engine. The components connecting the both parts have to be tight and perfectly aligned. You wouldn’t want to use noble metals for this cause, because you couldn’t drill through them on your own. I recommend using standard steel, at least 4mm thick, and over 20mm wide. Then the part will not bend and will work smoothly. To guarantee it will work well, something slippery between the bolts and hole edges would be necessary. I used a rubber line, and it worked perfectly.
4 Assembly
4.1 Order
I recommend starting the assembly from the front, and only then moving back. I scratched the bigger parts, such as the seat or floors because of putting them on first. You should start with the smallest and heaviest objects first, and only then move to bigger surfaces and bumpers. The steering system is a good place to start. It’s important to assemble the back axle as the last thing, as only then, after you have mounted the engine, will you be able to tell where the sprockets should go.
4.2 Geometry of the front axle
To make the front wheels perfectly aligned together, you have to do a bit of geometry. The first step is to hold the steering wheel, you can ask somebody to do it for you or just tie it up to the back of the gokart with ropes. After that, you will have to find two flat objects of the length of around 1m. Put them parallel to the wheels and measure both sides, the goal is to make both sides equal. To make it equal you have to either tighten, or loosen the steering rods.
4.3 Back axle
Arguably the most difficult part of the whole project is assembling the back axle. Its important for the axle to be clean- no paint, no grease and no bumps. Then you can start putting in whatever should be on the inside part (between the bearings) Then, you should put on the bearings which requires some kind of lubricant. If the lubricant doesn't help, resort to polishing the axle with sandpaper or the wire brush. After this is done, Align the bearings with where they should be and put the axle on the gokart. The axle won’t be perfectly in the middle, so you have to measure which side it should move to. Once you know that, hit it on the other side with a rubber hammer. Make sure it is perfect, and lastly, add the hubs. Screw the hubs in applying a lot of force since you don't want the wheel to come off. Also don’t remember to add the little screws on the bearing.
That would be it for building your own gokart. It is certain you will encounter challenges that are not listed here, but it's impossible to list all of them. Solving each issue requires some creativity and patience. Stay safe and have fun with your wonderful machine:)
hope that helped
Ooo, 9 year canoe?
In reply to kubulek :
Do you realize that his then 13 yo is now 22? Rather late on the info.
Run_Away said:Ooo, 9 year canoe?
At least it was a canoe with useful information.
alfadriver said:In reply to kubulek :
Do you realize that his then 13 yo is now 22? Rather late on the info.
Still 21, but yeah. He drives a Volvo S40 now. The kart thing never happened, unfortunately.
When I was a kid I wanted a cart more than anything in the world and I had no interest in mini bikes. My mother said something along the lines of, "No, they are illegal". I eventually discovered cars and finally built The World's Scariest Volvo. Now 45 years later, I am thinking about my future needs and how I need to start planning for when I can't get around on two legs very well. I want to buy a youth rear wheel drive 4 wheeler, replace the front hubs with 48 volt motors, come up with some sort of battery, put golf cart wheels and tires on it, and move the gas tank to somewhere else so it has a step through space like a Vespa scooter. Then I can drive to Walmart with the gas engine, drive through the front doors (less than 36" wide), drive around the store with battery power, and then drive gas powered home. :)
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