Dirt Bike Fuel System Maintenance and Fuel Performance Enhancement - Part 1
Tips and Tweaks to maintain and improve your dirt bike's fuel system.
Using Fuel Filters to reduce dirt bike maintenance coasts. Using a Fuel Stabilizer when storing your dirt bike to protect your fuel system.

 Dirt Bike Fuel System Maintenance 
 and Performance Enhancement Part 1

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 Tips and Tweaks to improve your dirt bike's fuel system

 Dirt Bike Australia - HOME

Motorcycle engines have evolved greatly since the days I rode an old Beeza (BSA) 250 around a back paddock as a kid (more than three decades ago). Carbys were a lot more forgiving and easier to clean than the high-tech fuel injection systems around today. This means that maintaining today's dirt bike in good working order and keeping it running reliably requires a little work than it used to.

Using an Engine Hour Meter
A good engine hour meter is one of the simplest items that you can add to your new dirt bike to help insure that bike maintenance occurs when it needs to. It's all to easy to put regular servicing off ... and to forget it altogether.

Regular Servicing at appropriate intervals will of course go a long way towards keeping a dirt bike in top shape. You might want to consider using the Motominder Engine Hour Meter to keep track of the total hours your dirt bike has actually been running. Keeping an accurate Service Log that shows all work done will also improve your dirt bike's resale value.

It's hard to stress this point too much. A lack of maintenance does not save a rider any money. Poor maintenance often means that engine wear starts to increase exponentially. This can result in major repairs that could have easily been avoided. So, read the manufacturer's handbook with regard to optimal servicing.

A regular maintenance and servicing regime will ultimately Save Money!

There are also simple things that you can do all the time and between servicing that will help to prevent problems before they start. One of these, and the main topic of this article, is Fuel Management.

Dirty Fuel and Stale Fuel are two fairly common yet avoidable problems that regularly confront dirt bike and ATV riders. Stale fuel can particularly be an issue when equipment is stored for extended periods. Both can lead to unnecessary, expensive engine and fuel system damage.

Dirty and Contaminated Fuel

Dirt and Debris in Fuel

It never ceases to amaze me, at how much grit and actual road gravel ends up in motorcycle fuel tanks. Even in road bike tanks that (supposedly) don't go any where near a dirt road. It seems that no matter how careful you think you are at keeping the rubble out ... somehow it manages to sneak into your fuel tank.

Fortunately there are some simple and cost effective solutions, like the comprehensive range of Australian made Pro-Fill Australia Fuel Filters  External Link , that will keep the rocks and grit out of your tank and prevent a dirty fuel problem before it starts.

Water / Condensation in Fuel

Another common problem is fuel that has been contaminated by water. This can be due to either condensation, particularly if the fuel tank is left mostly empty in cold weather, or from water in the fuel you get from the petrol bowser.

The first problem is relatively easy to avoid. If you keep your tank topped up at all times there will be little or no opportunity for water condensation inside the tank to become an issue.

Water in the fuel from the petrol bowser is a problem you may not be able to avoid. Particularly when you may be buying fuel with ethanol added. The huge storage tanks under the petrol bowser suffer from exactly the same condensation problems as your petrol tank, only on a vastly larger scale. The problem may be compounded at out-of-the-way service stations with infrequent deliveries of fresh fuel, meaning that the storage tanks may be at low levels for extended periods. As a result pools of water can develop at the bottom of these tanks.

Ethanol however, can dissolve water and carry it up and into your bike's petrol tank. When the ambient temperature is warm this water stays in solution, but a drop in temperature can reduce the amount of water suspended in the ethanol, and this water then settles to the bottom of your fuel tank. If enough water accumulates over time, it will cause performance issues and require the tank to be emptied out and cleaned thoroughly.

In both cases however, having a good Inline Fuel Filter between the fuel tank and carby (or injection system) will trap water and any particles suspended in it (like fine rust). A simple fuel filter can save dirt bike riders a lot of unnecessary down-time and maintenance, particularly related to stripping down the entire fuel system and cleaning jets.

Stale and Degraded Fuel - Best Practice for Storing Your Dirt Bike or ATV

Stale or Oxidized Fuel

All petrol is essentially unstable and should ideally be used in under 60 days.
Over time the volatile components that make up the fuel interact to form new compounds, mostly due to oxidation. Some of these new compounds are essentially "sticky" and will adhere to the inside of the fuel tank, fuel lines, carburetor or fuel injection system. It's not unlike the plaque that can build up in human arteries and eventually lead to heart failure. Same sort of thing, except it's your dirt bike that gets the heart attack.

This problem is particularly an issue for dirt bikes and ATVs that are stored and not ridden for periods lasting longer than a few months. It might be because you're away, recovering from an injury or just don't want to ride in totally crappy weather. The reason for not riding may be insignificant, however the problems caused by stale fuel are not.

Using a Fuel Stabilizer

Unfortunately (and annoyingly), the simplest solution of just draining the fuel system may actually make the situation worse. There will still be traces and droplets of "old fuel" in the system, which will degrade and gum up the works, and now there will also be condensation which may lead to corrosion. Removing the majority of the fuel may also cause some seals and O rings (that are designed to remain immersed in fuel) to oxidize and begin to perish as well.

The problem is not new and the solution, not surprisingly, has been around for quite a while. However, modern chemistry and technology have produced far more effective and reliable fuel stabilization products than were available even a decade ago.

At this time nearly all vehicle manufacturers specify (in their owner's manuals) filling the fuel system with treated fuel before any period of extended storage (generally more than 60 days). We strongly recommend that dirt bike riders should make this a part of their fuel management "Best Practice" whenever a bike is likely to be stored for a few months or more.

This Best Practice (which applies to both 2 stroke and 4 stroke engines) can be simply achieved by mixing a fuel stabilizer like STA-BIL®  External Link (or equivalent) with some fresh fuel, then running the engine for a few minutes to make sure the stabilized fuel has run through he entire fuel system. Problem solved!

Where storage is expected to be for longer than 12 months ... at or before 12 months (or as advised by the product's manufacturer), remove and/or dispose* of the old fuel and then repeat the above process by refilling the system with freshly treated new fuel.

* Ideally, you would remove the stabilized fuel from your dirt bike before the effect of the fuel stabilizer wears off. Put the fuel in your car or some other vehicle and use it immediately. Better for you, better for the environment. ... and no ... you don't put two-stroke fuel in your car! :-)

Over time, adopting this simple fuel maintenance practice will prevent a lot of unnecessary problems. It will improve a bike's overall long-term engine performance and save no small amount of money.

Dirt Bike Australia would like to thank Pro-Fill Filters and STA-BIL® for their assistance in producing this article.

Incept Date: 21/02/2010   Updated: 02/03/2010


 Dirt Bike Australia



The honest answer is that Fuel Degradation depends on a number of related factors. These would include:

  • Exposure to air - A filled container of fuel will oxidise a little slower than a half-filled one.

  • Temperature - The ambient temperature will effect the rate of oxidation, where heat will accelerate the process.

  • Additives - Some fuels contain more (performance boosting) additives than others. Some additives may extend the shelf-life of the fuel while yet others will reduce it.

The one thing that you can count on is that the situation is constantly changing. Fuel manufacturers are constantly tweaking their products to either reduce production costs or gain more market share. And they won't be sending out a memo to motorists every time there is a change.

Sometimes the changes will indeed result in better performance and/or economy.

But given the variables that effect a fuel's stability, there is no definitive way for us to know at any given point in time.

So most engine manufacturers prefer to err on the side of caution and say that fuel should ideally be used within 60 days.

Depending on storage conditions, it may be good for substantially longer. The question is ... Do you want to take that chance?

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