What is the valve clearance for a motorcycle?
2 Answers
Motorcycle intake and exhaust valve clearance is approximately 0.05 millimeters. During engine operation, the valves expand due to temperature increase. If there is no clearance or insufficient clearance between the valves and their transmission components when cold, thermal expansion during operation will cause incomplete valve closure. This leads to air leakage during the compression and power strokes, reducing engine power and potentially causing difficulty starting. Below are additional details about motorcycle valve clearance: 1. Standard valve clearance varies among different motorcycle models - intake and exhaust valve clearances may be equal or different. 2. Valve clearance is set to ensure proper operation of the internal combustion engine's valve train. 3. As the valve train operates at high speeds and temperatures, components like valve lifters and stems expand when heated, which could automatically open valves and cause incomplete closure with valve seats, resulting in air leakage.
Every time I repair my motorcycle, I notice the importance of valve clearance. Generally, the intake clearance is between 0.08 to 0.15 mm, and the exhaust clearance is around 0.12 to 0.20 mm, but this depends on the specific model; different models from Honda or Yamaha have their own standard values, so it's best to check the user manual. Too small a clearance can cause premature wear of the valves, while too large a clearance leads to increased engine noise and reduced power. When adjusting, you need to use a feeler gauge to measure, first operating with the engine cooled down, and some bikes even require adjustment after preheating. It's recommended to check every 5,000 km or at least once a year. If you're not familiar with the tools, it's safer to go to a professional repair shop to avoid damaging internal engine components. Proper maintenance can extend the engine's lifespan, reduce fuel consumption, and improve the riding experience. I think this small detail greatly affects overall performance.
