How to Clean and Oil a Foam Motorcycle Air Filter
Thoroughly clean dirt and old tacky oil from a foam motorcycle or ATV air filter, dry it safely, and re-oil the element for maximum engine protection.
This guide shows how to clean and oil a foam motorcycle air filter in 30-45 minutes. Start with remove filter and protect intake tract; follow the safety notes and step checkpoints below.
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- Read the tools, materials, safety notes, and steps below for free.
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🧰 Required Tools & Equipment
- ✓ Nitrile gloves
- ✓ 2 small wash basins or buckets
- ✓ Zip-top plastic bag (gallon size)
- ✓ Clean microfiber shop towels
📦 Materials & Supplies
- ✓ Dedicated foam filter cleaner
- ✓ Liquid or aerosol foam filter oil
- ✓ Mild liquid dish soap
- ✓ Waterproof rim grease
⚠️ Safety Checkpoints & Warnings
- • Wear chemical-resistant nitrile gloves to prevent solvent absorption and persistent tacky oil on skin.
- • Work in a well-ventilated space away from gas water heaters, sparks, or open flames.
- • Plug the exposed intake tract inside the airbox immediately upon filter removal to stop loose dirt from entering the engine.
📋 Step-by-Step Guide (6 Steps)
Remove Filter and Protect Intake Tract
Unscrew the air filter cage retaining bolt and gently ease the dirty filter out of the airbox. Immediately inspect the intake boot for grit and insert a clean, lint-free rag or dedicated wash cover into the intake opening.
- • Air filter is separated from the bike sitting in a work tray.
- • Intake tract is visibly sealed with a clean rag or rubber wash cover.
- • Knocking loose dirt crust directly into the carburetor/throttle body intake when pulling the filter out.
- • Leaving the intake hole completely open while moving dirty parts over it.
Dissolve Old Oil and Trapped Dirt
Separate the foam element from its plastic support cage. Submerge the foam in a wash basin containing dedicated foam filter cleaner and squeeze repeatedly from the inside out to break down sticky oil and sediment.
- • Foam element separated from the plastic frame.
- • Cleaner fluid turns dark and cloudy as old tacky oil liquefies.
- • Twisting or wringing the foam like a towel, which tears glued seams.
- • Using harsh gasoline or lacquer thinner that degrades the foam matrix and glue.
Wash with Warm Soapy Water and Rinse
Fill a second bucket with warm water mixed with mild dish soap. Squeeze the filter in the soapy water to strip remaining solvent and dirt, then thoroughly rinse with clean, low-pressure tap water running from the inside toward the outside.
- • Rinse water runs crystal clear through the foam.
- • Foam returns to its original bright factory color (e.g., yellow, green, or blue).
- • Rinsing from the dirty outside face inwards, which drives microscopic grit deeper into the foam pores.
- • Using boiling water that degrades foam glue joints.
Dry the Foam Completely
Press the foam gently between clean microfiber towels to remove excess water. Set the filter in a clean, dust-free, warm area and allow it to air-dry completely before applying oil.
- • Foam feels completely dry and fluffy to the touch with zero moisture residue on fingers.
- • Filter is rested on a clean, lint-free surface away from dust.
- • Applying filter oil while foam is still damp, which traps water and prevents oil adhesion.
- • Using a high-heat heat gun or clothes dryer, which shrinks and hardens foam.
Apply and Distribute Foam Filter Oil
Place the dry filter inside a clean gallon zip-top bag and pour in 2 to 3 ounces of foam filter oil. Work the oil thoroughly through the bag with your hands until the entire foam body has an even, saturated color with no dry spots, then squeeze out any excess oil.
- • Entire foam filter displays a uniform, consistent color (typically blue or red).
- • No dripping oil, but the foam feels evenly tacky throughout all layers.
- • Leaving pale, un-oiled dry spots where fine dust can pass straight through.
- • Over-oiling so heavily that oil puddles in the bottom of the airbox and chokes airflow.
Grease the Rim and Reinstall
Reinsert the internal support cage into the foam, ensuring all alignment pins engage properly. Apply a continuous 1/4-inch bead of waterproof rim grease along the sealing lip of the filter, remove the intake rag, and reinstall the filter firmly into the airbox.
- • Continuous unbroken line of grease around the entire sealing contact surface.
- • Filter sits flush and square against the airbox mating surface with the center bolt hand-tight.
- • Forgetting to remove the intake plug rag before bolting the filter down.
- • Overtightening the center wing bolt and bending the plastic cage.
Credit: inspired by an original tutorial by Rocky Mountain ATV MC — watch the original on YouTube.
Don’t have everything?
- No Foam air filter cleaner? Mineral spirits (odorless paint thinner) followed immediately by warm dish soap wash
- No Zip-top plastic bag? A clean plastic grocery bag or working oil into the filter directly using gloved hands
- No Waterproof rim grease? Standard heavy automotive wheel bearing grease applied to the sealing flange