What are the symptoms of small valve clearance in motorcycles?
2 Answers
The symptoms of small valve clearance in motorcycles are as follows: 1. Valve noise: The most common symptom of excessive valve clearance is abnormal noise, which mainly comes from the collision between the rocker arm and the valve. 2. Reduced power: The main reason for the decrease in power after excessive valve clearance is the reduction in intake and exhaust volume, primarily because the valve opening becomes smaller, thereby affecting the engine's intake and exhaust volume. 3. Unexpected damage: If the valve clearance is too large and not adjusted in time, for pushrod engines, there is a possibility of pushrod detachment. This is because the pushrod relies on the upper and lower rocker arms for positioning. If the clearance is too large, the pushrod may shift, leading to detachment.
I used to have trouble with valve clearance being too small when riding a motorcycle. The most prominent symptom was that it was particularly difficult to start, especially when the engine was cold—it took several attempts to fire up. At idle, the RPM was very unstable, fluctuating significantly, and the engine would even stall on its own when hot. Riding it felt sluggish, as if lacking power, and the exhaust would emit a harsh metallic knocking sound. If the clearance is too small, the valves won't seal properly after thermal expansion, leading to poor compression and low combustion efficiency. If not addressed promptly, engine wear accelerates, making repairs more expensive. I recommend checking the clearance every few thousand kilometers, measuring and adjusting it properly with a feeler gauge, ensuring your bike runs smoother.
