Ever since I started learning about go-kart engines and how go-kart clutches work, I’ve always heard about gear ratios. Having played many racing games when I was younger, I know that the gear ratio determines whether the vehicle accelerates faster or has a higher top speed.
There’s no best go-kart gear ratio that works for every track. A general rule is that a higher gear ratio will give your kart more acceleration, and a lower one will give it a higher top speed.
But it’s not that simple. Gear ratios are a complex and technical part of go-karting, especially when you have to tune your kart’s ratios. So, instead of looking at the technical side, let’s see how a gear ratio affects your speed around a track.
The Best Go-Kart Gear Ratios
A buzzword in go-kart gear ratios is the 6:1 ratio. While this isn’t optimal for every track, a 6:1 gear ratio provides your go-kart with enough top speed on the long straights and acceleration on the exit of tight corners.
Best Gear Ratio For Top Speed
If you’re racing at a track with many long straights, you’ll have to consider a lower gear ratio, like a 5:1 or 4:1, if you’re feeling risky. Remember that I’m talking about racing go-karts; gear ratios should be higher in offroad and rental karts.
That’s because a low gear ratio will wear out your go-kart’s clutch and engine very fast. So, if you’re thinking of running a 1:1 ratio, your engine will be dead after a few laps.
Best Gear Ratio For Acceleration
On the contrary, the best gear ratio for acceleration is higher, so in theory, something like 7:1 or 8:1 would be perfect. And, I say in theory because gear ratios don’t work with absolute values.
Every track is different, and no two gear ratios will work on two different high-acceleration tracks. That’s why you always need to talk to other racers, to see what setups they’re running. And, always remember to test out several gear ratios to find the perfect one for your driving style.
What Is a Go-Kart Gear Ratio
A go-kart gear ratio is the difference of teeth between the rear sprocket and the front sprocket (or engine sprocket). Things get very technical when it comes to gearing (modifying the gear ratio), so I’ll try to keep it as simple as possible.
The engine and the driveshaft (on the kart’s rear) have a sprocket, which looks like a gearwheel. The engine sprocket usually has between 10-13 teeth, while the rear sprocket has anywhere from 30 to 90 or more teeth. That’s why gearing usually means changing the rear sprocket by adding one with more (or less) teeth.
So, if you’ve got an engine sprocket with 12 teeth and a rear sprocket with 60 teeth, you’ve got a 5:1 ratio. And the lower the ratio, the higher your kart’s top speed.
But, with all this in mind, let’s see how gear ratios are different from one engine to another.
Do Some Engines Work Better With Different Gear Ratios
Some gear ratios work better for certain engine brands. For a gear ratio to work better on one engine, it needs to have the perfect maximum RPM for that ratio. Let me explain this with the example of IAME and Rotax engines.
Most Rotax engines max out at 14,000 RPM, while IAME engines can go up to 16,000 RPM. Considering that a high gear ratio will make you accelerate faster (so you’ll reach higher RPM more quickly), it’s safe to say that an IAME engine will work better with a high ratio.
That’s because the engine will come close to its max RPM, and thus it’ll be producing an optimal power output. But, in such cases, instead of adjusting the rear sprocket, you’ll need to change the engine sprocket.
I know this might sound confusing, especially if you’ve never tried adjusting a go-kart’s gear ratio. So, here’s an example. An IAME engine will run optimally with an engine sprocket that has 10-11 teeth. The Rotax counterpart will have much acceleration with the same sprocket, but it will reach its top speed in the middle of a long straight.
So, it’s good to know how much RPM your engine has before you start adjusting its gear ratios.
That’s about it when it comes to gear ratios. In reality, you won’t need to do any gearing unless you have your own go-kart and you’re racing professionally. And, every racer at your local track will be happy to tell you the best gear ratio for that track is.
Stay tuned for more articles just like this one!
FAQs for Go-Kart Gear Ratios
Does a Smaller Sprocket Make a Go-Kart Faster?
In terms of top speed, a smaller sprocket will make a go-kart faster. But, as I mentioned above, a smaller sprocket will leave you with less acceleration, which is vital on a technical track.