A good fuel and oil mix in your 2-stroke kart engine is crucial to look after the expensive components and to provide you with an edge against other drivers on the track. Regardless of what brand you own, it’s key to understand what the right fuel mix ratio is for your 2-stroke kart.
You should usually use a fuel ratio of 8 oz of oil to 1 gallon of fuel for a 2-stroke go-kart, which is 16:1. If you open the manual about your 2-stroke, there will be a recommended fuel to oil ratio that is considered the best for efficiency, safety, and keeping the engine properly lubricated.
Below, we take a look at the ideal fuel and oil mix ratios for various 2-stroke go-karts, including the Comer 51, the IAME X30, the Vortex Rok and the Rotax Max.
Comer C51 Fuel Mix Ratio
The ideal fuel mix ratio for the Comer 51 2-stroke kart engine is 16:1, with 8 oz of oil to 1 gallon of fuel. Some racers may use 9 oz of oil per gallon of fuel, and another common ratio is 21:1.
This highly popular engine is seen almost everywhere in kids karting, and even in higher age categories with a few tune-ups here and there. Due to how widely available this engine is, I felt that this was the best place to start due to its popularity as one of the most common 50cc engines on the market.
The most common mixture consists of 8 oz oil to one gallon of fuel, which makes the mixture 16-parts fuel to 1-part oil, or a 16:1 mix. Another commonly seen mixture is 6 oz oil to one gallon of fuel, making a 21:1 ratio. The latter mixture will save you some money while properly lubricating the engine, while the former is a lot more oil-focused to truly look after the Comer.
A variation on the 16:1 is one commonly used for races, and it involves increasing the oil volume to 9 oz per one gallon of fuel. The one thing to watch for when doing this is carbon build-up, so you’ll want to fully drain your engine after every race when looking for higher performance.
IAME X30 Fuel Mix Ratio
The ideal fuel mix ratio for the IAME X30 2-stroke kart engine is 25:1 (6.12 oz of oil per gallon of fuel), with a minimum of 20:1, ideally using 95-octane fuel.
Another fan favorite, this TaG-ready engine produces competitive horsepower and speeds within the 125cc race categories. This engine is typically seen in high-skill Junior divisions all the way up to Senior classes, and it’s celebrated for its versatility, high performance and reliability.
The Ideal Ratio
The manual for the X30 outlines the recommendation of fuel mixing to align with a 25:1 ratio, specifically stating that 95-octane gasoline is best.
The best types for an IAME engine are Castor Oils. Although this type of oil makes a gummy residue of carbon deposits, it’s the best for providing competitive lubrication even at high temperatures. The recommended oil brands are Shell Advance Racing M, Elf HTX 909 and ERG K Kart Formula.
Vortex Rok GP Fuel Mix Ratio
The ideal fuel mix ratio for the Vortex Rok GP 2-stroke kart engine is 25:1, or 6.12 oz of oil per gallon of fuel.
Yet another 125cc engine, the latest Rok engine of the bunch is favored in TaG racing for its varied innovations in coolant systems in order to keep it running for longer. 2-stroke engines work hard to deliver high power and torque for races, and the Rok does well to deliver on that raw power while also ensuring you won’t be shopping for replacement parts after every race.
The Best Ratio
Much like the IAME and quite a few other 125cc variants of engine, the manual for the Rok GP recommends a 4% fuel mix, which works out as a 25:1 ratio. Unlike other manuals, Vortex don’t suggest the best types of fuel and oil to mix together, and this indicates that the standard sorts work as intended.
Owners of the GP engine recommend a 100-octane gasoline for races, but for the purposes of being budget friendly, 94-octane fuel from a pump is acceptable for practice. Mix these together with Castor Oil at the 4% mix ratio and the engine will be running at its absolute best.
Rotax Max Fuel Mix Ratio
The ideal fuel mix ratio for the Rotax Max 2-stroke kart engine is 30:1, or 5.1 oz of oil per gallon of fuel. If you’re racing, you may want to use a ratio of 50:1 instead, with 3.17 oz of oil per gallon of fuel.
Above all else, Rotax is passionate about performance in racing, which is why some of their prices can be considered a little above what go-karting enthusiasts can comfortably pay. However, their Max 125cc engine really is something special! For high-performance engines, a very specific (and unusual) mixture of fuel to oil is required.
A Richer Fuel Mix
For the purposes of ‘breaking in’ the engine, Rotax recommend that a ratio of 30:1 should be used, putting the oil at about a 3% mix. Simply put, this is the best for running the kart under normal circumstances such as while you’re practicing. And for optimum performance, such as when you roll out your Rotax for races, they recommend a 50:1 ratio, which puts the oil at a 2% mix.
Unlike the IAME and Rok engines mentioned previously, the makers of the Rotax Max recommend fully-synthetic kart racing oil as opposed to castor oil. This is primarily because Rotax make all of their products specifically to work alongside one another, so they created a kart racing oil to specifically complement its most competitive engine.
How To Mix 2-Stroke Fuel For A Go-Kart
The 4 steps to mix 2-stroke fuel for a go-kart are:
- Pour the correct amount of 2-stroke oil into a clean gas can
- Add the correct amount of gasoline
- Stir or shake the container to mix the oil and gas together
- Use the mixture within 30 days of mixing
Sounds simple enough, right? It really is an easy process when you have your mixtures down. Before we get on to calculating/reading the fuel mix amounts, always remember the following tips:
- Don’t use automobile motor oil – It contains noncombustible additives that will damage your engine/make it impossible for combustion to occur. Only use 2-stroke engine oil.
- Never use gasoline with more than 10% ethanol – This is because ethanol attracts moisture, which causes gasoline to break down and that can cause engine damage.
- Don’t ever eyeball your gas and oil amounts – Make sure to properly measure everything according to the ideal ratio.
- Don’t mix gas and oil in the engine itself – Always use a separate, clean container to do the job.
- Allow the engine to fully drain – This is especially true when taking your kart out of winter storage.
How To Read 2-Stroke Kart Fuel Mix Ratio Charts
Alright, now it’s time for some Math! Exciting, right? Not for me, let me tell you that much. It never was my strong suit but it’s really crucial for getting your fuel mixes right and having a general know-how about the different charts you’ll come across.
Most ratio charts will actually come with two different units of measurement listed: milliliters per liter and ounces per gallon. Because of this, you don’t have to do the tricky conversions between liters and gallons or vice versa. If all else fails, remember that 1 liter is equal to approximately 0.26 of a gallon.
2-Stroke Kart Fuel Mix Example
When figuring out the amounts of gasoline and oil to fit your listed ratio, you first need to look at how much gasoline you have. For example, let’s say that you want to mix your fuel to the Rotax recommended base-line of 30:1 and you have 2 gallons of gasoline. How much oil should you add for your fuel mix to be correct?
- You take your fuel volume, which is 2 gallons, and convert it to ounces, which is 256
- Then divide that latter amount by the ratio you want, which in this case would be 30
- 256 divided by 30 would equal 8.5 oz, so you would mix that amount of oil in with your gasoline
Most charts will make it very clear for you, but it’s always nice to have the formulas you need to work things out by yourself in the workshop when you don’t have one to hand. Nevertheless, you can find different fuel mix charts online and print one off so you have it handy.
The right fuel mix ratio for your 2-stroke kart engine will vary depending on the kart you own. Some ratios will be 16:1, while others can be as high as 30:1. You also need to make sure you use the right type of oil, so it’s best to check your manufacturer’s instructions just to be safe.
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