One of the elements that causes the most confusion in karting is chain size. The chain is the component that drives the wheels of the kart, so it’s important to get this right, or else you’re leaking performance. So, you might be wondering how to choose the right chain size for your kart.
Go-Kart Chain Size Chart
| Chain Number | Pitch | Roller Width | Average Tensile Strength |
| #35 | 3/8″ / 9.5 mm | 3/16″ / 4.8 mm | 2,100 lbs / 952 kg |
| #40 | 1/2″ / 12.7 mm | 5/16″ / 7.9 mm | 3,700 lbs / 1678 kg |
| #41 | 1/2″ / 12.7 mm | 1/4″ / 6.35 mm | 2,000 lbs / 907 kg |
| #420 | 1/2″ / 12.7 mm | 1/4″ / 6.35 mm | 3,700 lbs / 1,678 kg |
| #428 | 1/2″ / 12.7 mm | 5/16″ / 7.9 mm | 4,200 lbs / 1,905 kg |
| #50 | 5/8″ / 15.9 mm | 3/8″ / 9.5 mm | 6,100 lbs / 2,766 kg |
How To Read A Go-Kart Chain Size Chart
When you’re presented with the go-kart chain size chart above it all might seem a bit confusing and difficult to comprehend at first. But there isn’t actually that much to it. First of all, it’s worth noting that there are several other chain sizes available, but to make it easier, we’ve narrowed it down to the six most common chain sizes that are used in karting.
While there are several other sizes, you likely won’t be using them in karting as they are much larger and heavier, and this will impact the performance of your kart. If the chain you’re using is too big, then your kart will struggle in terms of performance, and there’s a chance that you could damage the engine.
So, how does it all work? Well, the first number of the chart gives you the pitch measurement, and this makes it easier to read a chain and know what pitch it has straight away. For example, the #35 chain has a 3/8” pitch (9.5 mm), the #40, #41, #420, and #428 chains have a 1/2” pitch (12.7 mm), and the #50 chain has a 5/8” pitch (15.9 mm).
The Basics
In other words, the higher the chain number, the stronger the chain will be. Stronger chains are required for more powerful engines. Shifter karts, for example, use a #428 chain, which is likely to be the highest you’ll use on any (race legal) go-kart. If you make modifications to it, you might need a stronger chain.
Smaller karts such as cadets, junior class karts, and even senior max will use smaller chains than that. In karting, you’ll usually be between the range of #35 and #420 chains. In that range, there are even more variations such as #35-1, #35-2, and so on. These will vary in strength and size, but the most common chain for racing karts is the #35-1.
It’s important to keep in mind that each chain requires a different sprocket. For example, your usual 12-tooth front sprocket and 85-tooth rear sprocket setup will work differently with a #35 chain compared to a #40 chain. Keep this in mind when playing around with your setups or taking advice from others on which sprockets to use.
How To Know What Go-Kart Chain Size You Need
The size of your kart chain will play an important role in the performance of your kart. Having the correct sizing on your chain could gain you several tenths per lap, and it can give you that much needed boost in the straights and out of the corners.
On the other hand, having the wrong size chain will slow your kart down. Not only that, but it could also cause damage to the chain and the sprockets. These parts might not be all that expensive, but if you’re not keeping an eye on the wear and tear of the chain and the sprockets, then you’re at risk of having them fail while out on track, or even during a race.
You will need to adjust the size of your kart’s chain whenever you change the sprockets on your kart. Changing to a smaller or a larger sprocket will cause the amount of tension in the chain to change, and this is when the performance loss and wear and tear can start to flare up. Changing sprockets is essential though, so it’s important to know when you need to change the size of your chain.
The general rule of thumb is to always check the tension on your kart’s chain whenever you change the sprockets on your kart, and we’ll get into this process later. Most of the time, moving up or down by one tooth should not make a big difference, but it’s always best to check before you head out onto the track for a race.
How To Measure A Go-Kart Chain
There are a couple of different ways that you can measure your go-kart chain. Firstly, there’s the overall length of the chain, which will affect the tension of the chain, this is most important when changing the sprockets on the kart.
You can also measure the tensile strength of the chain which is determined by the pitch. This will impact the performance and the reliability of your kart as it will add more resistance to the chain with the trade-off that your chain will be stronger.
Finally, there’s the roller diameter. This will measure how wide the kart’s chain is. In general, the width of the chain will always be the same for karts, but this will also determine the tensile strength of the chain.
Sometimes you’re lucky enough to have the measurements of the chain printed onto the master link. But this is not always the case, so if you still need to measure your kart’s chain, here’s how to do it.
Chain Length Measurement
The length of the chain is generally used when changing the sprockets on the kart. When you change to a sprocket that has more teeth, you’re going to need a longer chain to relieve the tension and resistance that the chain has and allow it to move in a much smoother and easier way. Moving to a smaller sprocket will require a shorter chain.
Adjusting this is as simple as adding in extra links or removing links as needed next to the master link. The length of the chain is determined by how many links there are in total (excluding the master link) in the entire chain. However, this is something that you would probably not have to measure at any point in time.
The general rule is that you simply need to add or remove links whenever needed. If you can’t move your axle or engine mount forwards or backward to relieve or add tension, then adjusting the number of links in the chain is the next best solution.
Chain Pitch Measurement
Measuring the pitch will help you to determine the overall weight and strength of the chain. The stronger the engine is, the stronger the chain needs to be. For example, the lightweight and weak chains we use on karts won’t work on a motocross bike, and the chains used on these bikes would be too large and heavy for the kart’s engine to turn the rear axle.
So, how can you measure your chain and determine if you have the right one? That’s where the pitch comes in. Pitch is the distance between the pins on the outer layer of a chain link. You can measure the pitch of a chain simply by measuring the distance between the two pins and then check out the table at the start of this article to see how the measurement fits in with a chain number.
You can also measure the pitch your kart needs by measuring the sprocket. Sprockets have a bunch of teeth, and if you measure the distance between the two teeth, it should correlate with the distance between the two pins (the pitch). Once again, you can use this measure to find the right chain for your kart setup.
In order to measure the pitch, you’re going to need to be precise. It’s usually best to use a wrench or vernier caliper to measure the distance between the two pins. Getting an accurate measurement will help ensure that you use the right chain.
Chain Roller Measurement
The other difference between chains is the roller pin measurement. When it comes to karts, most use the same roller pin size, but there may be one or two chains that offer a different roller pin measurement.
The roller pin simply determines the tensile strength of the chain. A thicker roller pin will have higher tensile strength (meaning it requires more force to reach its breaking point), so it’s sturdier and can take a heavier load. The entire chain will also be slightly narrower or wider depending on the roller pin measurement.
There is also a chain roller width measurement which is simply the measurement from one end of the pin to the other, measured using the inner plates (not the outer plates). This will also play a role in the tensile strength and the width of the chain.
KEY POINTS
• It’s essential that you use the right size of chain on your go-kart
• There are various ways to measure kart chain size
• Measuring things accurately will ensure you use the correct chain size
How Tight Should A Go-Kart Chain Be?
Your go-kart chain should be tight enough that there is about an inch (2.5 cm) of flex at the center of the chain. This isn’t an exact measurement, but instead is just a general guide. Having your chain too tight or too loose can drastically affect your kart’s performance.
If you work on your own kart, you’ll know that the chain is incredibly sensitive, and the tension on it can change easily. If you change the sprocket, clean the chain, move the engine back and forth, or even ride the kerbs too hard, the tension on your kart will change. The reality is that the tension on your kart’s chain is crucial to running your kart properly, much like the chain on a bicycle.
Too Loose
If your chain is too loose, there’s a chance that it could jump off when your kart goes over bumps or kerbs at high speed. Loose chains can easily come off, but they also affect the performance of the kart because there is not enough grip between the sprocket and the chain for the crankshaft to drive the rear wheels. So, you might find that your kart is struggling to get the power down.
Too Tight
If the chain is too tight, you’ll find that the performance of the kart is still affected. With a tight chain, the crankshaft needs to work harder to drive the kart forward. If the engine can’t work any harder, you’re losing performance. On top of that, a chain that is too tight will be shaving down the sprockets and causing the teeth to go blunt which, over time, will cause them to become completely useless.
This means that one of the easiest ways to check if your kart’s chain has been too tight is to simply compare the sprocket on your kart to a new one. You’ll notice that some of the gold paint is peeling off, which is normal wear and tear, but try to compare how much the sprocket’s teeth have been worn down compared to the new sprocket and you’ll be able to see if there’s a clear difference.
Checking The Tension Of Your Kart’s Chain
Your kart’s chain needs to have a specific amount of tension in order to maximize performance, but not have the chain dislodge from the sprocket and the clutch. Unfortunately, there’s no specific measurement you can use to determine whether your chain has the right amount of tension or not.
That’s because every sprocket is a different size, and every chain is also unique. But there is a general guideline that karting mechanics and drivers use to “measure” their chain’s tension. When you’ve got your setup ready to go you can slightly move your chain up and down right in the center where the tension is at its lowest.
There should be around one inch (2.5 cm) of play (flex) in the chain. This will allow the chain to be loose enough to prevent friction and resistance that makes the engine work harder and lose performance. At the same time, the chain will be tight enough to keep it from dislodging from the kart.
Why Do Go-Kart Chains Get Loose?
Go-kart chains can get loose for a variety of reasons, and it’s usually just a natural consequence of you driving the kart. Any minor setup changes you make can affect the chain’s tightness, so it’s important to check your chain’s tension every time you’re about to go out on track.
Over time, the chain on your kart will become looser. This doesn’t necessarily mean that something is wrong, as there are several reasons your kart’s chain could be coming loose. It’s important to constantly check the tension on your kart’s chain. It’s easy to make a habit of checking it whenever you do your general maintenance and check-up before heading out on track for the day.
General Maintenance
Taking care of your kart is crucial. Racing karts are so sensitive that they need to be maintained constantly. The majority of karting drivers and kart owners know that they need to do some general maintenance and a quick check-up before they even start their kart ahead of the day’s driving.
But this maintenance can often involve moving around the engine, axle, and sprocket, or just cleaning in that general area. Perhaps it’s time for quick service of your kart’s clutch, or you were just checking the conditions of the shoes.
Whatever maintenance you might be doing in this area, even if you’re just cleaning up dirt and oil, there is a chance that you could be moving some of these elements, which can change the amount of tension on the chain.
Kart Setup Changes
If you’re racing in a traveling championship that visits a new track for every event, then you’re probably used to making setup changes on your kart, more specifically to the sprocket. Even if you’re always racing on the same circuit, you might still be changing your sprocket during testing or to get the edge over your competition in a certain session.
You could also be making adjustments to the axle and the rear track width, or simply making some changes to the engine itself. Making these adjustments will also change the tension of the chain, which likely will need to be readjusted after you have completed your setup changes.
Bumps & Kerbs
Even if you’re not making setup changes and you’re incredibly careful not to move anything around while cleaning the kart, your chain might still be moving around and the amount of tension may change. This simply comes down to the general usage of the kart.
While driving the kart, you’ll always be running over bumps or hitting the kerbs. This is natural, and it’s usually unavoidable, especially if you’re competing and you want to drive your kart as fast as possible! But hitting these kerbs and bumps can put a strain on your chassis as it flexes and bends to get over these obstacles.
This can cause the axle and the engine mounting to move ever so slightly, causing the chain on your kart to loosen up. Depending on the movement and flex of the chassis, the chain could also become tighter. That’s why it’s so crucial to constantly check the amount of flex in the chain whenever you do any general maintenance and check-up of your kart.
KEY POINTS
• If your go-kart’s chain is too loose or too tight, your performance can suffer
• There should be about an inch (2.5 cm) of play in your kart’s chain
• It will naturally become loose as you use the kart, which isn’t a concern
Final Thoughts
Chain size is an important factor to consider on your kart. You need to make sure to use the right chain or else you could suffer performance issues. You could also damage your kart by using the incorrect chain. The most commonly used chain in kart racing is #35, and it’s safest to go with this option unless you need a stronger chain.
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