Choosing the wrong fuel for your motorcycle can be catastrophic. I hear a lot of chatter of mixed opinions when it comes to what fuel is best for your dirt bike. So here are some basics to insure you don’t harm your bike and also get the optimal performance.
What is Race Gas?
There are a wide variety of race fuels on the market that can get very technical and specific to many different motorcycle set up. In general people refer to race gas as high quality 100+ octane fuel, but can be as high as 120+. To make things simple octane is basically the flash point of the fuel, so if you have a higher octane fuel it takes more engine compression to detonate the fuel. The purpose of this is so you can control your fuel ignition timing to match your specific engine.
Is Race Fuel Good for a Stock Motorcycle Engine?
Stock motorcycles are optimized to run on premium pump fuel (premium octane levels will vary with altitude usually 91/93). This mean that, even though its smells amazing, race fuel is not the right choice for your stock motorcycle. However, this doesn’t mean you have to buy cheap fuel at your cheapest local gas station. You can still buy high quality fuel that is better for the longevity of you your motorcycle engine and is contaminate free. You just need to stick within your octane rating range based recommended for your motorcycle, if you go above this rating the engine combustion will occur later than it is designed to.
When Should You Use Motorcycle Race Fuel?
The purpose for race gas is that it allows you to select a fuel that detonates at a higher flash point for high compression motors. This prevents too early of a fuel detonation before the piston finishes the compression stroke causing harm to the motor (aka engine knock). This is usually only a problem is modified high performance engines that have had either head work done or a high compression piston installed. The level of octane you select will very depending on how much compression your bike has. This will usually be between 100-120 for a “high compression” engine.
Can You Boost Octane Rating?
If you’re in a bind with no access to race fuel you can boost the octane of your pump fuel to the desired rating by adding an “octane booster.” This is usually a last resort move though, you should try to buy the proper octane fuel to begin with. Also be cautions of the mixing quantities, they can be confusing with their “octane points.” 1 octane point doesn’t necessarily mean that it increases your octane rating by 1.
Can You Mix Different Octane Level Fuels?
Yes you can mix different octane level fuels together to adjust your octane level to something in the middle. This works well if you need to achieve an octane somewhere in the middle of the two fuels you have access to. I have done this in my 2-stroke that has the head shaved only 20 thousandths, this was a conservative compression increase so I have found my bike runs best with just half 110 octane fuel and half premium (91 octane) pump fuel.