The right air filter is the type your airbox was designed for. Most road bikes and scooters use a paper element that you replace rather than clean. Motocross and enduro bikes use oiled foam that you clean, re-oil and reuse. To find your part number, use our motorcycle air filter chart, which matches 284 air filters to 813 models across 28 makes.
Foam or paper?
Paper filters
Pleated paper in a frame. It is not designed to be washed or oiled: replace it at your service interval, or sooner if you ride in dust or it looks dirty, damp or damaged. Most of the filters in our air filter chart are Hiflofiltro, and many are listed against the original part number they replace in our OEM part number cross reference.
Oiled foam filters
Off road bikes face far more dust, sand and mud, so they use open cell foam, usually in two layers: coarse on the outside, fine on the inside. The oil is what traps the fine dust, so a foam filter must never be run dry. Dirt that gets past the filter quickly wears the piston, rings and cylinder, so only fit a filter listed for your model and year.
Pre-oiled or non-oiled foam?
Our RFX foam filters come in two versions. Part numbers ending 55PO are pre-oiled; those ending 55NO are non-oiled.
- Pre-oiled filters are ready to fit straight from the bag, with no mess. They make a handy race day spare.
- Non-oiled filters arrive dry, for you to oil with the foam filter oil you prefer.
After the first wash, both are cleaned and re-oiled the same way. Many riders keep two or three filters so a clean one is always ready.
Popular MX models and the filter we stock
These rows come straight from our fitment data. FXAF 50008 and FXAF 50007 are our most widely fitting RFX filters, listed for 38 and 33 models across KTM, Husqvarna and GasGas. Filters often change with a new generation of bike, so check your year on the product page.
For other bikes, see the air filter chart, all air filters or the RFX range.
How to clean and oil a foam air filter
Off road, check the filter after every ride, and clean it after every ride in dust or heavy mud. Follow your owner's manual and the instructions on your cleaner and oil.
- Wipe the dirt from around the airbox before you remove the filter, then plug the intake with a clean rag. When you wash the bike, a wash cover keeps water out of the intake; the RFX wash cover FXAW 50004 55ST is listed for the same models as filter FXAF 50007.
- Take the filter off its cage and wash it in a dedicated air filter cleaner. Squeeze gently and never wring or twist it, which can tear the foam or split the seams. Do not use petrol.
- Rinse as the cleaner directs, squeeze out the water and let the filter dry fully at room temperature, away from direct heat.
- Replace the filter if the foam is torn, the seams are lifting, or it has gone hard or crumbly.
- Wearing gloves, work foam filter oil through the whole filter until the colour is even, then squeeze out the excess. It should be fully coated but not dripping. Leave it for the time given on the can.
- Remove the rag, refit the filter to its cage and seat it squarely in the airbox. If your manual calls for it, put a thin film of grease on the sealing rim. Dirt on the clean side of the airbox usually means the filter is not sealing or is damaged.
We stock Maxima FAB-1 Foam Filter Oil 385ml, the Maxima Air Filter Maintenance Combo Kit with cleaner and spray oil together, and Motoverde Air Filter Cleaner in 5 litre and 1 litre sizes. See all filter care products.
How to find the filter for your bike
- Open the motorcycle air filter chart and choose your make.
- Find your model and check that your year falls inside the listed range.
- Open the part to see its price, stock and every bike it fits.
You can also search with the parts finder, browse parts by bike model, or look up an original part number in our OEM part number cross reference. Still not sure? Email sales@apexpowersports.co.uk with your make, model and year.
Delivery and returns
UK Next Day delivery is £7.99, free on orders of £100 or more, with Pre 12:00 at £9.99 and Pre 10:00 at £14.99. We are online only, so there is no collection. Returns are accepted within 30 days from delivery, and the buyer pays return postage unless the item is faulty, damaged or wrong. See delivery and returns.