How to Change the Coolant in a 1981 Yamaha PW50
Shop parts for a 1981 Yamaha PW50 Dirt Bike.
The 1981 Yamaha PW50 is a legendary entry-level dirt bike that has introduced generations to off-roading. Unlike more modern liquid-cooled dirt bikes, the PW50 features an air-cooled, two-stroke engine. This means there is no liquid coolant system to service or replace. Instead, owners need to focus on routine maintenance involving the oil injection system, transmission oil, and final drive lubrication.
What You Need to Know About the 1981 PW50 Cooling System
- No liquid coolant: The PW50's air-cooled design uses cooling fins on the cylinder and head to dissipate heat, so it does not requireor useradiator coolant.
- Oil Injection System: The bike relies on a separate two-stroke oil tank to lubricate the engine. Regularly check and top off the injector oil with the recommended two-stroke oil.
- Transmission Oil: Change the transmission oil regularly to keep the gearbox running smoothly. Use a 12mm socket to remove the drain plug, allow oil to drain, replace the crush washer, refill with approximately 300 milliliters of the recommended oil, and reinstall the fill cap and drain plug to spec.
Routine Maintenance Steps to Keep Your PW50 Cool and Protected
- Inspect cooling fins: Use a soft brush or compressed air to remove any mud or debris from the engine fins at every wash. The fins are critical for proper air cooling.
- Check oil levels: Before each ride, make sure the oil tank is filled with two-stroke injector oil up to the fill line.
- Change transmission oil: Warm the engine, remove the drain plug and crush washer, drain oil, clean and reinstall the drain plug with a fresh crush washer, refill with 300ml of fresh oil, and replace the fill cap.
- Maintain final gear drive: Grease the final drive case every two years using lithium soap-based grease to keep the shaft drive running smoothly and reduce wear.
Special Considerations for the 1981 PW50
- Simple, Reliable Design: The PW50's lack of a liquid cooling system is intentionalthere is no radiator or coolant reservoir, making it one of the simplest bikes to maintain.
- Parts Compatibility: Many key maintenance partslike the transmission crush washer, oil, and air filterare easy to find and swap, supporting decades of reliability.
- Pro tip: Always keep the oil injector system in perfect working order to avoid engine damage.
If you were searching for information on changing coolant in the 1981 PW50, rest assured: the only cooling this model needs is fresh air across clean fins and a well-maintained oil system. Keep up on transmission and drive maintenance for a bike that keeps running ride after ride.
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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.