Is Ethanol Bad for Dirt Bikes?

There are many things you will need to know when you buy your dirt bike. When you first add fuel, you will find yourself looking at the choices at any gas station and wonder which is the right one to choose. Ethanol is a type of alcohol added to modern fuels to add efficiency to the gasoline and create fewer greenhouse gasses.

Yes, ethanol will damage 2 stroke engines but is perfectly safe for use in larger dirt bikes and will increase performance for 4 stroke engines.

Ethanol can be used for short periods with 2 stroke engines, but the damage done to such an engine over a long period will be irreparable. Meaning you will need to be sure when to use the fuel and whether you should be keeping it as far away from your dirt bike as possible.

These are the things you should know about using ethanol and using it with your dirt bike.

Ethanol used for engines

When creating fuel for engines, even dirt bikes, there is a specific level of combustion that is required. This level is when the internal piston compresses the fuel mixture, and a spark sets it all off, creating energy to let the engine work. There are a few things to know about ethanol fuel and what additions are made to the fuel before you pour it into your bike.

  • Fuel mixture: Ethanol is never used as the only fuel in a dirt bike; it will always be a mixture of fossil fuel, ethanol, and methanol that is used. Ethanol fuels are, therefore, mixtures of three or more chemicals that help the engine perform better by having hotter temperatures.
  • Methanol: This is often the addition to ethanol fuels that few people know about, it has a more stable reaction than ethanol and is a lot easier to produce.
  • High temperatures: Because ethanol is an alcohol that increases the temperature that fuel produces when it explodes, requiring the engine compartment to handle more temperatures when the fuel explodes easily. This can be with the housing and cooling system that the engine has.
  • Residue: While ethanol and methanol are used to clean things completely when not lit on fire when added to fossil fuels, there is a danger that over time there will be a build-up of residues that can cause damage if not cleaned.
  • Oil Breakdown: Something that not a lot of people know about two-stroke engines that are used in dirt bikes, is that they have oil mixed in with their fuel. This provides lubrication and a lot of other needed things; however, with ethanol added to the fuel, the oil can be broken down, which will cause long term damage.

What is ethanol and methanol?

There are usually two types of alcohol substances that are used in everyday life, methanol, and ethanol. Each of these are used in specific purposes and are combustible, however, you are more likely to encounter ethanol than you will be methanol.


You will know ethanol as normal alcohol, used in everything from hand sanitizer to the alcohol that you can drink. Ethanol has only a few negative effects if used responsibly, with the added effect that it will easily light on fire like all alcoholic substances.

This is why old movies like to show cars being boosted, performing better when someone throws some brandy, whiskey, or rum into the fuel tank of the car. This enabled the car to perform better owing to the low ignition levels the mixed fuel has. With fuel that has lower ignition levels, the engine can now work less to cause an explosion.

Ethanol is easy to find, and unless you have access to high quantities of pure ethanol, then there is no danger to be had with it.


Also, part of the alcohol family and having similar properties to ethanol, this is the more dangerous and purer version of alcohol that should be treated with care. People use methanol for cleaning of medical equipment, sometimes in engineering and many other scientific fields.

While methanol is like ethanol, with similar combustion temperatures and evaporation levels, there are a few key differences that make it not preferred by people that need ethanol combination fuels. Methanol is a lot less expensive to produce than ethanol. However, it is more toxic and can cause blindness in humans when drunk.

While it can increase the combusting potential of normal fuel, it is not as effective as ethanol.

Why ethanol is required

Older engines from the early 20th century required their fuels to be supplemented with several different types of extra chemicals. This was because the engines were inefficient and needed extra help to work properly. At the start, these were fuels with lead or other dangerous chemicals that were removed from fuels as we learned the dangers to the environment that these chemicals caused.

As we started to develop engine technology, fuel became purer, and engines no longer needed so many additives to them. However, as engines continued to be developed, the fuel required became more specialized. This means that new additives became a necessity to ensure that all the vehicles could work properly.

This is when alcohol, or ethanol, was introduced to fuels, as a clean way to ensure the fuel can work correctly, and as required. This led to all fuels in most countries containing some ethanol to work properly. As cars continued to gain popularity, people started using vehicles in more extreme environments.

Dirt bikes being small and lightweight quickly required specialized fuels as well. Luckily, things calmed down, and a standard type of fuel was created that almost every vehicle use to this day. Eventually, high-performance engines required more combustible fuels; these can be anything from racing fuel to jet fuel.

The addition of ethanol to fuels created fuels that could perform better and increase fuel efficiency. To the point that all fuel in the US now contains 10% ethanol, this means that modern dirt bikes are ready for these fuels. However, you may have an older dirt bike that cannot handle mixed ethanol fuels.

Ethanol will increase the efficiency and strength of your dirt bike, but you must be sure that it can handle the increased temperatures caused by ethanol fuels.


Whether you are using a new dirt bike or you are using a dirt bike that was made several decades ago, you should be able to find the fuel you need easily. Getting your dirt bike ready for a long and eventful weekend playing in the dirt, mud, or sand is as easy as choosing the right fuel. Ethanol is perfect to increase the efficiency of your dirt bike and will not damage it if you use the right type.

So grab your dirt bike, fuel it up and go have fun in the sun knowing that your engine will continue to work no matter what!

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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