How to Change the Coolant in a 1986 Yamaha PW50

Shop parts for a 1986 Yamaha PW50 Dirt Bike.

Keeping your 1986 Yamaha PW50 running cool is crucial for reliability and longevity. If you are searching for coolant service, there's a unique point to consider: the PW50 does not use a traditional liquid coolant system. Instead, this model is equipped with an air-cooled two-stroke engine. That means no liquid coolant changes are required. Instead, cooling is managed entirely by airflow over the cylinder fins during riding.

However, the PW50 does have essential fluids to maintain:

  • Injector oil (two-stroke oil): The injector oil tank sits behind the front number plate. Always keep this tank filled with high-quality two-stroke injector oil to avoid engine damage. Top it up whenever it reaches the low mark by removing the cap on top of the tank and pouring the oil in carefully.
  • Transmission oil: Changing the transmission oil is a key maintenance step. Warm up the engine briefly, then remove the transmission drain bolt with a 12mm socket and let the old oil drain completely. Clean and replace the crush washer on the drain bolt, reinstall it (torque to 10 foot-pounds), and refill with 300ml of the recommended transmission oil. Don't forget to clean the oil fill cap before reinstalling.

1986 Yamaha PW50 Model Details:

  • This dirt bike features an air-cooled, automatic two-stroke engine tailored for young riders. The absence of a radiator or coolant hoses means maintenance is simplified and there's less risk of overheating failure due to coolant loss.
  • Periodically check that the cooling fins on the cylinder are free from mud and debris. Clean them gently with a soft brush to maintain proper airflow and cooling performance.
  • The PW50 uses a power reduction plate in the exhaust that can be removed for full performance or reinstalled for beginners who need less power.
  • Always use the correct type and amount of two-stroke oil for the injector system, as improper lubrication is the chief cause of engine failure on this model.

In summary, your PW50 does not require a coolant change. Just keep an eye on the two-stroke injector oil, transmission oil, and clean cooling fins regularly for reliable performance season after season. Regular, model-specific maintenance ensures your vintage Yamaha PW50 continues to be a dependable and fun machine for new riders.

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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.