A clutch is an essential part of your go-kart, which engages and disengages the power transmission. This allows your go-kart to accelerate by transferring power from the engine through the crankshaft to the rear axle and ultimately the rear wheels.
The reason your go-kart clutch is smoking is that it’s not properly engaging. To be more specific, the friction material of the clutch is not making enough contact with the outer drum. The lack of friction inside your go-kart’s clutch causes it to generate excessive heat and smoke.
There are many causes to why your clutch may not be properly engaging. In this guide, we’ll be taking a closer look at these reasons, why they can lead to your clutch smoking, and most importantly how you can fix it.
How Go-Kart Clutches Work
Before I start going into more detail on the reasons, let’s get familiar with what a go-kart clutch is designed to do and how they work. Below, you’ll see the inside view of a go-kart clutch and all of the individual components.
Go-Kart Clutch Description
- Tension Spring
- Friction Material
- Flyweight/Shoe
- Pivots
Once your go-kart accelerates by pushing down the accelerator pedal, the engine spins the crankshaft, on which the clutch is mounted. As the crankshaft spins faster, the friction material and flyweight of the clutch get pushed outward (typically at around 1,400 RPM to 1,600 RPM) and make contact with the clutch drum or casing.
This occurs due to the centrifugal force that the flyweight and the friction material are exposed to – hence, they’re also called centrifugal go-kart clutches. The tension springs ensure that the flyweight materials don’t instantly push outward at lower engine speeds. Take note that a clutch is fully engaged at about 1,800 RPM.
Reasons Why a Go-Kart Clutch Can Smoke
As you’re able to see from the illustration above and from how a go-kart clutch works, it’ll become more apparent how they can actually start smoking if the clutch isn’t fully engaged.
As go-kart clutches start to only fully engage at about 1,800 RPM, any slower rotation of the crankshaft can cause the clutch to “slip”. When a clutch slips, it’s known not to fully engage, and not enough friction is asserted to the friction material to “grab” onto the inner clutch drum.
This phenomenon will cause your go-kart clutch to generate so much heat that it starts to smoke, especially when it’s slipping over a longer period. There can be various reasons why your go-kart’s clutch is slipping and smoking. Two of the most common reasons are that you may not be accelerating faster enough or that you’re simply driving too slow.
Other reasons include having an incorrect rear ratio, an incompatible clutch, worn clutch tension springs, a damaged clutch, accidental oil spillage inside of the clutch, or simply an incorrect installation of a clutch. Let’s take a closer look at these causes so that I can teach you how you can fix them fast!
Reason 1: Not Accelerating Fast Enough
When you’re not accelerating fast enough, your go-kart clutch won’t transition from a disengaged to a fully engaged mode. The incomplete transition, also known as slippage, will generate heat, which in turn can cause your clutch to smoke.
This usually happens when you accelerate and your engine operates at a low RPM range for too long. But don’t worry, there is a very simple fix for this!
How to Fix It: All you’ll need to do is accelerate faster. You don’t have to push the “pedal to the metal” when accelerating, but I advise you to push the accelerator pedal down more firmly, to avoid slippage while accelerating.
Reason 2: Driving Too Slowly
Similar to accelerating too slowly, driving your go-kart at too low speeds when the clutch isn’t fully engaged will also lead to heat generation, as the clutch isn’t locking with the outer drum, causing it to smoke.
For reference, any engine speed that’s below about 1,800 RPM may cause your clutch to smoke from not being fully engaged. You may need a data logger or a go-kart speedometer to retrieve accurate RPM values.
How to Fix It: A simple fix for this is to drive your go-kart at higher speeds. To be sure, it’s best not to drive at engine speeds less than 1,800 RPM. If you wish to operate your go-kart off-roads or at slower speeds, you may want to consider a torque converter instead. Here’s a quick guide on go-kart clutches vs torque converters for a detailed comparison.
Reason 3: Incompatible Go-Kart Clutch
There are various types of go-kart clutches available on the market. While the most common type of clutch is a centrifugal clutch, they can be built to support different types of loads and speeds.
A go-kart clutch that isn’t designed to withstand the forces that are exerted onto it can cause it to get damaged – eventually leading to smoke. Therefore, I always recommend using a suitable and heavy-duty clutch for your go-kart.
How to Fix It: Fixing an incompatible clutch is simply not worth your time. You may need to replace many individual components (tension springs, pivots, and flyweights). Therefore, it’s best to just get a compatible clutch for your go-kart. Check out my reviews on the best go-kart clutches. In that review, you’ll also find a buying guide to help you out with your selection.
Reason 4: Worn Tension Springs
Clutch tension springs are designed to help restrict the flyweights and the friction material from pushing out immediately, particularly when your go-kart is idling. If that were the case, it wouldn’t be able to idle.
Worn clutch springs can also lead your clutch to smoke and also cause your kart to start moving when it’s idling. A sign of worn tension springs is typically due to excessive usage, incorrect clutch engagements, or other internal damages to the clutch.
How to Fix It: There are two options that you can select from. You can either remove your clutch, open the drum and replace the tension springs or you can simply get a new clutch to replace the old one. New tension springs will ensure that the clutch stops smoking, as it will start engaging at the optional RPM range again.
Reason 5: Damaged Clutch (Friction Material)
When your clutch isn’t engaging at the optimal range and is slipping over a longer period, it can generate heat, causing it to smoke. Moreover, you may also find that the friction material is excessively worn and in some instances can melt with the inner drum.
How to Fix It: When your go-kart clutch is smoking because it’s damaged (particularly the friction material), it’s best to either replace the entire flyweight with the friction material or the entire clutch. If you’re not experienced with fixing a clutch, I recommend simply replacing it.
Reason 6: Oil Inside the Clutch
There’s a common misconception when it comes to oiling a go-kart clutch. While you should be regularly maintaining your clutch, which includes oiling it once a while, you must ensure that oil doesn’t enter the clutch.
A go-kart clutch is only oiled around the bushing. You should never oil the interior parts of your clutch as that causes it to never fully engage. This is because the lubricant causes it to constantly slip. Read my complete guide on oiling a go-kart clutch correctly.
How to Fix It: If the interior parts of your clutch are exposed to oil, there is a way to fix this. Firstly, you’ll need to remove your clutch from your go-kart and then disassemble it. Then you’ll need to soak each component with a degreasing agent. Let them soak until all of the oil is cleared off. You can then reassemble your clutch and reinstall it. You clutch should stop smoking now.
Reason 7: Incorrect Clutch Installation
Installing your clutch correctly is a prerequisite for it to function optimally. An incorrectly installed clutch can lead to excessive slipping, which causes excessive heat (and ultimately causes your clutch to smoke).
How to Fix It: If you’ve installed your clutch incorrectly, proceed to completely remove it from your go-kart. Next, inspect if the clutch is still working properly and that it isn’t damaged. After that, reinstall your clutch correctly onto the crankshaft. Check out my comprehensive guide on how to install a clutch on a go-kart that shows you the step-by-step process.
Reason 8: Incorrect Gear Ratio
Another reason why your go-kart clutch is smoking could be due to your gear ratio not being steep enough. Go-kart gear ratios typically range between 8:1 to 4:1, depending on how aggressive the settings are.
This means that the rear axle sprocket is 4 to 8 times “larger” than the clutch sprocket. To be more precise, it means that the rear axle sprocket has 4 to 8 times the amount of teeth the clutch sprocket has. Increasing the gear ratio will ensure that your go-kart accelerates faster.
How to Fix It: You can increase the gear ratio (making it steeper) by either decreasing the number of teeth on your clutch sprocket or increasing the number of teeth on your rear axle sprocket. For more information, make sure to read my guide on go-kart gear ratios.
Frequently Asked Questions
I know that some of you may not be familiar with fixing go-karts, especially when parts like your clutch are smoking. Therefore, I’ve created a section where I address some of the most frequently asked questions, which you can find below.
What Should I Do When I Notice Smoke Coming From My Clutch?
When you notice that your clutch is smoking, the first thing you should do is turn your engine off and stop your go-kart. Take it back to where you can properly assess what’s causing your clutch to smoke. Once the clutch has cooled off (it will be very hot!) you can assess the damage and why it’s smoking.
If your go-kart clutch needs to be fixed, maintained, or is wrongly installed you may refer to some additional guides that I wrote:
Do I Need to Replace My Clutch If It’s Smoking?
Whether you need to replace a smoking clutch depends on what’s causing it to smoke. If it’s due to your driving habits (slow acceleration or too low speeds) or due to incorrect installation you typically don’t have to.
If the result of the smoke is due to clutch damaged or worn parts, I highly recommend that you either fix the affected parts or install a new clutch.
How Do I Know When My Clutch Is Smoking?
A clutch that’s smoking will be quite easy to spot. Apart from seeing white or gray smoke, you’ll also be able to smell burnt metal. This smell comes from the friction material and the inner drum of the clutch rubbing against each other as a result of not fully engaging.
