One of the biggest mistakes you can make when you get on a track for the first time relates to preparing the fuel mixture. Racing karts have
two-stroke engines, which need a so-called "mixture", i.e. a mix of gasoline and lubrication oil, to work. The oil enters the engine and is burned together with the fuel, acting as a lubricant for parts subject to sliding, such as bearings and elastic bands, that is, the rings placed on the piston that come into contact with the cylinder. A mixture composed of a percentage of oil that is too low or even absent, that is, supply the engine fuel only, causes a very high wear of the mechanical components and rapid overheating, arriving in a short time to the seizure of the piston inside the cylinder. To know the correct mixture value, you have to check the technical data sheet of the engine installed on your kart or directly contact the dealer/manufacturer.
When preparing the mixture for amateur kart use, it is better to add excess oil, rather than the opposite. In fact, a mixture richer in oil than the ideal value can lead to more smoke from the exhaust and to soil the ducts more quickly, giving less serious consequences than having less oil than is necessary. The oil must be the specific one for high-performance two-stroke (2T) kart engines, preferably of the brand and type indicated by the manufacturer.
How should the mixture be prepared by calculating the correct oil intake?
- Check the actual litres delivered by the petrol pump, for example 5 litres.
- Beware of the calculation! It is not just necessary to calculate the percentage on the volume of fuel to obtain the requried volume of oil. In fact, a 3% mixture means 97 parts of fuel to 3 parts of oil and not 100 parts of fuel and 3 of oil. So the most correct and accurate calculation is as follows:
Volume of oil = (Volume of fuel) / (1 - (% oil/100)) - Volume of fuel For example, a 3% mixture per 5 litres of fuel:
Volume of oil = 5 / (1 - (3/100)) - 5 = 5 / 0,97 - 5 = 0,154 liters = 154 ml For the correct dosage it is better to use a graduated measuring vessel.
- Put the oil into the tank and shake it for a perfect emulsion of the oil inside the fuel.
- Add the mixture into the kart tank.
At the end of a day on the track, it is important to empty the tank. The mixture can be stored in a cool, dry place for no more than two months, after which it must be disposed of. Otherwise, you can reuse it to clean some parts of your kart, for example the transmission chain-gear wheel-sprocket.