Can you use E85 in your Dirt Bike?

There are many different blends of gasoline. We will most commonly find Regular or Premium at the gas station, but blends such as E10, E15, and E85 are also available. You should check your Dirt Bikes owner manual to check what the manufacturer recommends when choosing what gasoline to use, but in general, can dirt bikes use E85 fuel?

Dirt Bikes can run on E85 fuel for short periods of time, but long-term use can cause engine problems. Long-term use of E85 in your Dirt Bike will cause corrosion of the aluminum components and embrittlement rubber components in your engine’s fuel system. E85 is not recommended for use in 4-Stroke dirt bikes.

It is great to experiment with different fuel blends in your dirt bike, but let’s look at the factors to consider before using a blend like E85?

What kind of fuel do Dirt Bikes Use?

You can use Premium Gas from your local Fuel Station, but many riders prefer to use high-quality racing fuels. These fuels consist of high octane, non-ethanol-based fuels specially made for racing. Always check your bike’s user’s manual for the manufacturer’s recommendations.

Why do some Dirt Bikers use E85?

Some dirt Bikers use E85 for short races to boost power by 15% versus Regular 87 Octane. The engine needs to be specifically tuned to run on E85 as it will combust much faster and would thus require the ignition timing to be advanced. Fine-tuning the ignition timing combined with an Octane taring of 115, using E85 fuel can boost power by up to 30%. E85 is only for experts capable of making the required adjustments in ignition timing and doing the additional servicing.

Why is High Octane Important?

A higher Octane-rating means that the fuel needs a higher temperature at which to ignite, thus avoiding premature ignition in the engine. This helps the engine to run cooler and convert the energy in the fuel more efficiently into power. You should look to use fuel with an Octane rating of 90 to 94 in your Dirt Bike. If you have a 2-stroke engine, remember to add the 2-stroke oil to your fuel tank when filling up.

Avoid Ethanol based fuels?

Ethanol is commonly used in fuels as it acts as an Octane booster. The problem is that ethanol produces a lot of moisture(water) when it combusts. This moisture can cause a lot of corrosion of your engine parts. It can clog up your engine over time. It is best to avoid using Ethanol based fuels for this reason. Occasionally using a tank of ethanol-based fuel like E85 will not be a problem, but it should be followed by using a good quality high Octane, Non-Ethanol fuel to burn off any moisture in the engine.

Fuel Consumption using E85

Ethanol contains less energy when compared to Regular or Premium gasoline. This means your fuel consumption will be significantly higher when running on E85. Comparing the ethanol molecule with that of regular gasoline, it is evident that Ethanol has far fewer Carbon to Carbon bonds. It is in these C-C bonds that the energy is contained.

What happens during Combustion?

In the Combustion Chambers of the engine, the fuel is injected along with some air. On the upstroke, the piston then compresses the air and gas mixture, and the spark plug ignites the gas mixture, causing an explosion that forces the piston back down again. The exhaust gas of the explosion is then expelled from the combustion chamber. For the engine to run efficiently, the timing of the movement of the pistons, the injection of the air and fuel mixture and the spark provided by the spark plug, and finally expelling the exhaust gas all need to be finely controlled. If combustion is efficient, the exhaust gas will consist of Carbon Monoxide and Water Vapour.

2-Stroke Vs 4-Stroke Dirt Bikes

2-Stroke Engines tend to be smaller and lighter than 4-Stroke Engines because they are of a simpler design and have fewer components. 2-Stroke Dirt Bikes require a High-Octane Fuel mixed with 2-Stroke Oil in the recommended ratio. They are cheaper to maintain than 4-Stroke Bikes, but they need the extra lubrication provided by the 2-Stroke Oil. 4-Stroke Engines are bigger and more complex than 2-Strokes and can run on Lower-Octane fuels. They also do not require any oil to be added to the fuel.

Can E85 be used in a 4-Stroke Dirt Bike

Due to the higher complexity and maintenance costs of a 4-Stroke Engine, it is not recommended to use E85 in your 4-Stroke Dirt Bike. These engines require complex calibration of the fuel management system to enable Flex-fuel such as E85. It is not worth the risk of serious engine damage.

Pros and Cons of using E85

Boosts power
Increased resistance to detonation
Low-cost vs. race fuels
Increased Octane rating
Attracts moisture
Corrosion of Aluminium parts
Degrades rubber components
Increased maintenance required
Only for occasional use
Not recommended for 4-Strokes


When considering the use of E85 in your 2-Stroke Dirt Bike, it is important to understand the impact on the engine. You can use E85 occasionally, but this will require adjusting the ignition timing on the engine. You will also have to reset the timing again once you fill up with regular gasoline next time. The prolonged use of E85 will adversely affect your engine and shorten the lifetime of components in the engine. The savings derived from using E85 fuel do not offset the resultant poor fuel consumption and increased maintenance.


Louis Pretorius

As an amateur off-road enthusiast, I have always been drawn to outdoor adventure. I have decided to share all of my learning experiences with you as I dig a little deeper into my new-found passion and wonderful world of off-roading. My mission is to create the Ultimate Off-roading space on the internet in the process. Stay safe and happy Off-Roading!

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