Air Filter Cleaning – Replacement Guide for 1979 Kawasaki KX250
Shop parts for a 1979 Kawasaki KX250 Dirt Bike.
The 1979 Kawasaki KX250 is a legendary motocross bike valued for its lightweight chassis and robust power delivery. Keeping your KX250 performing at its peak requires routine air filter maintenance — an essential task for both maximized airflow and motor longevity.
Why Air Filter Care Matters
Off-road riding exposes your KX250 to plenty of dust, sand, and debris. The air filter prevents this grit from entering the engine, but only if it's cleaned and oiled properly. Neglect causes loss of power and accelerated engine wear.
What Makes the 1979 KX250 Unique?
- The 1979 KX250 uses a foam-style air filter designed to maximize breathability while trapping fine dirt particles.
- This era KX features a unique airbox and filter mount. Always double-check that the filter fits fully against the basket and the airbox edges for a reliable seal.
- Unlike modern snap-in systems, the 1979 filter mounts with a wire or plastic cage. Carefully inspect the cage for cracks or corrosion every cleaning – a damaged cage quickly leads to leaks and dirt ingestion.
Step-by-Step: Air Filter Removal
- Remove the seat – typically a single 12mm bolt at the rear.
- Unfasten the airbox cover. Depending on your bike's condition, there may be original clips or upgraded fasteners.
- Gently pull out the air filter and supporting cage. Inspect both for damage.
How to Clean Your KX250 Air Filter
- Tap the filter to dislodge loose dirt.
- Wash thoroughly using a cleaning solution designed for foam air filters, or gentle dish soap & warm water. Avoid gasoline – it breaks down both foam and glue.
- Rinse until water runs clear. Squeeze (do not wring) excess water out and air dry completely.
- Once dry, coat the filter evenly with foam filter oil. Massage the oil into the foam, ensuring full and even saturation.
- Wipe excess oil off the filter frame and edges.
Inspection Tips: Don't Miss These 1979-Specific Troubles
- Check for splits or deterioration in the 1979 filter material, especially seams after years of use.
- Inspect the sealing rim on both the airbox and filter for cracks or dry rot.
- Make sure the filter cage is perfectly intact; warping or rust is not rare on vintage models.
Reinstalling – and When to Replace
- Install the filter evenly against the airbox, secure the cage or retainer, and verify the seal is airtight all around.
- If the foam is stiff, crumbling, splitting, or won't hold oil, replace immediately.
Pro Tips for the 1979 KX250 Air Filter
- Keep a spare filter oiled and ready to swap between motos for faster turnaround.
- Avoid over-oiling – excess oil can drip into the airboot and affect jetting.
- Inspect the airbox drainage hole for clogs and use waterproof grease on the sealing rim for an extra-dusty ride.
Staying ahead of air filter maintenance on your 1979 KX250 will help preserve this vintage machine for years to come, whether you're racing classics or trail riding. Always use a quality foam filter and proper oiling products for best reliability.
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Disclaimer: This guide is provided for general informational purposes only and is not intended to replace your motorcycle's official owner's manual. Always refer to your manufacturer's documentation for model-specific instructions, torque specifications, safety procedures, and maintenance requirements. If you are unsure or inexperienced, consider seeking assistance from a qualified mechanic or technician.
