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Is the ethanol content in gasoline a problem for my motorcycle engine

In most countries we now see that the fuel that is available to us contains a certain amount of ethanol. 
There are a lot of rumors and assumptions on what this means for our motorcycle engines and what kind of problems it can cause.
Here is all the facts you need.

Here is why ethanol in gasoline is bad for your engine.


In most countries the gasoline is now mixed up with ethanol, and the ethanol content is usually 5, 10, or even 15 percent.

This is a special challenge for all gasoline burning motors, but in some ways even more so for the motorcycle engine.

Here is a short list of the issues the motorcycle engine is facing because of the ethanol content in the gasoline.


Ethanol is hard on rubber parts (tubes, orings, gaskets)
  • This was a major problem on the first generations on motorcycles that was forced to run on ethanol infused gasoline. 
  • Today, the rubber parts have developed and even though the problems are not completely gone, it is no longer a massive problem.
Ethanol is hygroscopic (loves and attracts water)
  • A problem that can not be avoided. The ethanol will attract water and moist and if the water content gets high enough, the water filled ethanol will separate from the fuel and drop to the bottom of the fuel tank.
Ethanol is corrosive
  • Not the biggest problem, but the ethanol can create oxidation on aluminum parts and the white powder from the aluminum oxidation can block fuel supply lines.
Ethanol ages fast
  • The ethanol content is not the only factor here, but modern fuel decays rather fast, and if you have stored the bike for the winter, it can be really hard to start on old fuel when the spring arrives.
Ethanol have less power than gasoline
  • Energy content in ethanol is 33% lower than in gasoline. This means that the engine power will be lowered when the ethanol content goes up.
  • This is a real issue for the motorcycle engine that is already weak at low RPM’s because of the lean air/fuel requirements.

What can we do about these problems ?

We can not change the type of fuel available to us, but there are a few things we can do to minimize the problems with the ethanol content in our gasoline:


When you have the choice, go for the lowest ethanol content.
  • Your engine will be slightly stronger (important for the motorcycle engine at low RPM), and the negative effects of the ethanol content will be minimized.
Keep an eye on rubber parts, gaskets and o-rings.
  • Consider these parts as consumables and make sure you have new o-rings and gaskets ready when you take something apart on the bike. You WILL need them.
Store your bike in a dry place if possible
  • This will minimize the amount of water in the fuel.
Drain the tank if you are storing the bike for extended periods
  • If that is not practically possible, store the bike with a minimum amount of fuel in the tank and pour in 5 liters of fresh fuel before starting it up again.