How to Determine the Chain Size for a Go-Kart

Determining the right chain size for a go-kart is essential because it allows the rotary motion from the crankshaft to be transferred to the rear axle smoothly. This is done through the front and rear sprocket, which are connected by a go-kart chain (also known as a roller chain). 

When it comes to determining the chain size for your go-kart it’s important to understand the basics. You should familiarize yourself first, before attempting to buy, adjust or modify a roller chain. You can familiarize yourself with the go-kart chain size chart that I created, in order to understand more about the different sizes. It will also help you to understand how to read the sizes correctly. 

You’ll need this information, in order to determine the chain size for your kart. However, if you want the short answer, you can determine the chain size of your go-kart by using a wrench to measure the sprocket teeth width. I’ll explain this in a full step-by-step guide further below.

What Size Chain Do I Need for My Go-Kart?

The first thing that you need to know is that you should never adjust your sprocket, axle or engine position because you have a particular chain size. If you have an existing sprocket set up, you should buy a chain that suits your sprocket configuration. I’ll teach you how to measure this later on.

If you’re building your own go-kart or don’t have existing sprockets, you can buy them in a set. Buying a sprocket and a go-kart chain in a set would make it easier to install, as all you need to do is to shorten your go-kart chain to the required length.

So, let’s get to the point. In order to determine what size chain you need for your go-kart you need to measure it and then look at the go-kart chain size chart to match your results to know which chain you need. I’ll explain how to measure your go-kart chain in the next section. 

How to Measure a Go-Kart Chain

Measuring a go-kart chain is extremely simple. Let me quickly brief you on the different parts of the chain so that you know what I’m referring to. As can be seen in the illustration below, the roller width is how wide the chain is.

The roller diameter determines the diameter of the individual rollers. The pitch measures the distance between each pin. The pitch is what we are looking for when it comes to understanding chain sizes.

Go-kart chain numbers take the first letter from the pitch. And the last 1 or 2 digits from the roller width. For example a 420 chain has a pitch of 4/8-inches and a 520 chain has a pitch of 5/8-inches. To start measuring your chain size you need to start at the sprocket. Take a 5/8-inch wrench and hold this against the sprocket teeth.

You’ll see that the gap between two teeth equates to the roller chain pitch. The front and the rear socket must have the same tooth distance. It’s even easier to do this with an adjustable wrench.

For example, if you take a 5/8-inch wrench and it perfectly lines up with the sprocket teeth, you’ll know that the go-kart chain is either a 40, 41, 420 or 428. You can also use the wrench and hold it against the chain to check the pitch of the chain for confirmation. 

Once you have determined if it’s a 5/8-inch pitch, you can then proceed to check if they are wide teeth or thin teeth. For large teeth sprockets, you want a smaller roller diameter and for small teeth sprockets you want a larger roller diameter. If you don’t have a wrench, you can also use a measuring tape. Check out the video below for better reference.

Additional Information: The most common go-kart chain sizes are 35, 40, 41, 420, 428 and 50.

How Tight Should a Go-Kart Chain Be?

A go-kart chain shouldn’t be too tight or too loose. Therefore, getting a correctly sized go-kart chain is important, as a chain that is too short or too small can exert a lot of stress on the sprockets, causing faster wear and tear. The chain can also break, if it’s installed too tightly due to the physical stress it’s under.

On the other hand, a chain that is too large or loose increases the risk of dislodging from the sprockets. When this happens, the chain can get caught in the rear wheel causing you to lose control of your kart. In the worst case scenario, the go-kart chain can fling out and cause damage to others.

So, how tight should a go-kart chain be? A go-kart chain should have about 1/4″ or 3/8″ of flex. This means that once you’ve installed the chain on the sprockets, it should feel relatively tight with a little bit of slack. To measure the flex, you can simply pinch the chain at the sprocket and pull. You’ll then be able to measure the amount of flex it has.

Why Do Go-Kart Chains Get Loose?

As with any moving parts on a go-kart, they’re subject to wear and tear. The more often you race your go-kart the faster it will wear and tear. However, this isn’t necessarily bad. You shouldn’t hold off using your go-kart often. Instead look into proper chain maintenance so that it will last longer.

A go-kart chain can last a couple of months to a few years, depending on how often your go-kart runs, the type of chain and how well you maintain it. You should ensure that your chain is the right size and that it’s also lubricated. This will lengthen the roller chain lifespan.

You should check your go-kart chain every time you do regular maintenance. At the same time, you should also check the sprocket wear and replace them, if necessary. I personally replace sprockets and chain together as they wear out at a similar rate on my go-kart.

Go-Kart Chain Keeps Coming Off

If your go-kart chain keeps coming off, the most common reason is because it’s too loose. You may think to remove a few links in order to tighten your chain but this is not recommended. Wear and tear will shave off metal from the pins causing it to become loose. 

In this case you should replace your existing chain with a new one. Removing links on a worn chain is not recommended! There could also be other potential reasons, find our more in the guide on how to fix go-kart chains that fall off. 

Conclusion

I hope that this guide was insightful for you and that you were able to determine what go-kart chain size you need. I also hope that you’ve learned more on how to measure your go-kart chain. Feel free to leave a comment if you have any questions and will attend to them accordingly.