Clean Up Your Act

Air filters are very simple in design but do a very important job. You need to take care of your air filter so follow our guide to filters, cleaning and ensuring you get the best engine performance

If you race three times on a dusty track without oiling on your air filter, then kiss goodbye to that £250 engine!

An air filter, just like the infamous advert on UK television, does exactly what is says; it filters the air! OK so you understand what it does but we need to understand how it works and what is the best way to preserve it. In simple terms, an ineffective air filter will have major repercussions at the engine.

Most air filters fitted are simple. They use a foam section that purifies the air that passes through it before it gets pulled into the carburettor and afterwards, the engine. Most companies use a single tube of foam or there are paper versions available but the latter are certainly less popular. Then there are two-stage filters, which can use the same type of foam in both elements, or can utilise two different foams to get better results. These adopt the same principle as a single stage version but then the second foam sleeve slides over the top. This increases the volume of foam and thus does a better job. Some drivers opt not to oil the sleeve and I am one as I feel that the outer sleeve should have different filtering characteristics than the second.

Foam air filters need oiling to work effectively.


Whatever filter type or design you use, it needs to be cleaned and re-oiled regularly. Many companies will sell you either pre-oiled or replacement dry filters for a few pounds so bear that in mind. It is easy to tell when a filter needs changing. You can look at the foam and in a dusty environment, will have a layer of dirt on the top. In less dusty conditions, this is harder as it will not show on the filter but you may feel a difference in performance. As a filter by purifying the air, it will slowly have an effect on the air entering the engine. As less air gets in, the engine will become richer with fuel and the performance will be affected. In this situation, it is time to change or clean the air filter.

The cleanest way to oil the foam filter is in a bag.


With some set ups, you can simply remove the screw in the end of the air filter and slide the foam off. If you have a new one ready oiled to go on, then simply check for dirt build up around the plastic and rubber mount and remove it carefully, without letting and dirt go into the carburettor. Then slide a new one on, refit the screw and then you are off again.

If you need to clean the foam, then remove it in the same way and run a sink with some hot water and washing up liquid. Work some more washing up liquid into the filter and then thoroughly wash it in the sink. The air filter should then be well rinsed, removing any cleaner or water before being allowed to dry completely. After this, the filter can then be re-oiled.

Work the oil into the filter so that the foam fully absorbs it.


RB Concepts, Kyosho, Mugen, K&N, Medial Pro and Fioroni all offer good quality air filter oils. We found that the best way to lubricate an air filter is to use one of the coloured ones on the market as these clearly show when it has been correctly oiled as they naturally change colour and it is easy to check that the oil has been absorbed throughout the filter. To check though, you can always rub your finger over the foam and if it is ready for use, your fingers will have some oil residue on them.

Wipe of any excess oil using tissue paper.

First of all, get all the bits to hand and this will include a clean and dry foam filter, some filter oil and a transparent plastic bag, ideally colourless. Take the foam in one hand and apply some filter oil to the inside section. Then place the filter in the bag, which will allow you to work the oil through the filter, without getting your hands greasy! The oil needs to work its way completely through the filter, until it appears on the outside. If necessary, you can always add a little more oil to the filter. Only when the filter shows off a consistent colour throughout, can you stop and check it. Try not to use too much oil but if this is a problem, then you can dry the filter off a little in some paper towel. What is important though is to try and make sure that when you carry out the same process again, that you achieve the same consistency of oil as this more of less oil in the filter will affect the engines performance a little. Naturally, this is more critical in competition but is worthwhile trying to achieve this anyway.

Assemble the foam onto the filters plastic housing.


Some manufacturers supply a mounting brace for an air filter to offer some support for it but otherwise, you can make your own. Use the screw that holds the plastic end car pin place and bend a piece of piano wire around it – a washer may help to hold the wire in position. You then need to find a suitable location to secure the other end. This may involve using a self-tapping screw in the receiver box but make sure that it does not screw into your receiver or battery pack. The wire mounting should support the weight of the air filter, making sure that it is less likely to vibrate off. filter filter oil


If possible, you should always try and use the same type of air filter and oil. Changing brands of either may require an adjustment to your engine’s settings as they can affect the flow of air. Of course, there may be instances when you need to change filter deign but then make sure that the carburation is still OK before running.

First Timers

When you first get an air filter, you may have to build it up from its component parts, You will often get a cable tie to hold the plastic bottom section to the flexible rubber part that slides over the carburettor. Here at Racer, we will always superglue the rubber to the plastic as well as fit a cable tie for added security. When you fit the competed air filter to the carburettor, always use a cable tie and pull it tight to prevent air or dirt bypassing the filter. You should not hope that a push fit is good enough as the air filter will come off, especially with an off-road model.

Do not, under any circumstances, drive your nitro RC vehicle without an air filter. You will hurt it.


Share →

Leave a Reply

Your email address will not be published. Required fields are marked *