Air Filter Cleaning & Replacement Guide for 1979 Yamaha IT250
Shop parts for a 1979 Yamaha IT250 Dirt Bike.
The 1979 Yamaha IT250 stands as an iconic enduro designed for off-road performance, renowned for durability and responsive two-stroke power. Maintaining peak engine protection and maximum airflow demands routine attention to the air filter—an especially critical task for this model given its unique intake location and era-specific foam design.
Why Regular Air Filter Maintenance Matters
- Prevents dust and debris from entering the engine and causing premature wear.
- Maximizes engine performance by ensuring optimal airflow.
- Maintains the model’s legendary reliability for both trail and competition use.
1979 Yamaha IT250 Air Filter Overview
The IT250 uses a foam air filter positioned in the airbox directly under the seat. The most commonly used aftermarket option is the Uni-Filter (fitment number NU-2241ST), designed for both the 1979 and 1980 IT250 for superior filtration and airflow– See fitment notes from manufacturers.
When choosing a replacement, select a two-stage foam filter for improved trapping of both fine and coarse particles—this design delivers noticeable horsepower and torque increases for vintage Yamaha classics.
Cleaning Steps: Proprietary MotoSport Method
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Preparation
Remove the seat carefully using the seat bolts. Detach the air filter cover, and gently pull the filter from the airbox. Take care not to drop debris into the intake tract. -
Inspection
Scan the foam for tears, thinning, or degraded seams. Replace immediately if damaged. IT250 foam can degrade over time, and aged filters may crumble on removal. -
MotoSport-Approved Cleaning
Fill a shallow tub with warm, soapy water (MotoSport recommends mild, biodegradable motorcycle-specific cleaner). Submerge filter and gently squeeze repeatedly—do not wring or twist—until all dirt is released. Rinse with clean water until foam is free of residue. -
Drying
Lay on a clean towel and pat surface water away. Air dry completely in a shaded, well-ventilated area. Do not use compressed air or direct sunlight, as vintage foam is vulnerable to rapid deterioration. -
Re-oiling
Apply quality foam air filter oil evenly. Use a light squeeze to work oil through the filter without leaving dry patches. Excess oil restricts flow—the IT250 needs free breathing for proper fuel-air mixing. -
Reinstallation
Confirm airbox and filter cage are spotless. Refit the filter, ensuring perfect sealing edges so unfiltered air cannot bypass. Replace cover and seat.
Replacement Recommendations
- Replace your air filter if cleaning does not restore softness or if the foam shows signs of collapse or unraveling.
- Vintage models occasionally develop airbox leaks—inspect gaskets and seals while the filter is out, and replace as necessary.
IT250 Model-Specific Insights
- The 1979 IT250 was delivered with a high-flow airbox and unique subframe mounting, making filter access easier than many competitors of its era.
- Owners racing or riding in extreme dust should consider carrying a pre-oiled spare, as filter saturation happens rapidly in sandy or silty terrain.
- Genuine IT250 foam filter replacements are becoming rare. Aftermarket foam filters (like Uni-Filter’s NU-2241ST) offer enhanced durability and filtration performance.
- The stock airbox must remain sealed—any modification to intake will impact carburetion and may lead to engine damage. Always verify the filter fit after installation.
Final MotoSport Pro Tips
- Clean and inspect your filter every 3-5 rides, or more often in severe conditions.
- Store spare filters in sealed bags to prevent contamination between swaps.
- Document filter changes to ensure optimal maintenance intervals.
Related Shopping Categories
Shop Air Filters for a 1979 Yamaha IT250 Dirt Bike.
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Shop Air Box Covers for a 1979 Yamaha IT250 Dirt Bike.
Shop Tools for a 1979 Yamaha IT250 Dirt Bike.
Shop Intake Parts for a 1979 Yamaha IT250 Dirt Bike.
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.