The function of the cam is to perform some special changes and outputs during a circular motion. Therefore, there will be frequent intermittent impacts. The camshaft of a motorcycle uses this change to open or close the valves. The motorcycle's engine has a very high rotational speed, and although the camshaft is only half the speed of the crankshaft, it is still very fast. For example, the idle speed of a single-cylinder motorcycle can reach over 10,000 revolutions per minute. Triggering the valve action through unevenness at such a high speed causes a significant reactive force impact. Therefore, the strength of the material is very high, often using alloys or similar materials. If the material quality is poor, it is prone to problems. 

1. The motorcycle engine itself operates through explosive combustion. The camshaft is installed on the cylinder head.

The temperature is extremely high because appropriate engine oil is needed to maintain lubrication and reduce temperature. If there is a lack of engine oil, such as a narrow design of the oil pipe, it may cause damage to the camshaft due to the lubrication problem. The pedal motorcycle is inherently sealed, and the heat dissipation is not as ideal as that of a motorcycle rider. The engine oil needs to be replaced frequently to ensure lubrication and cooling performance. If the engine oil is abnormal, it is prone to cause high-temperature damage to the camshaft.

2. Most pedal motorcycles have a horizontal engine. The space is small, and the bearing seat of the camshaft is designed as an open type for ease of disassembly. It is not an integrated cylinder head. Therefore, there is a problem of clearance fit. The processing and assembly of the hole positions are prone to deviations. If the assembly or maintenance is not standard, the screws may be tightened too tightly or too loosely, or there may be some impurities, which will cause an imbalance in the bearing load.

The raceway will deform and be damaged due to the pressure and abrasion of the balls. 

3. The quality of the bearings is very crucial. Heat treatment is very important. There are too many inferior products on the market. Cheap pedal motorcycles often use poor-quality products. As long as there is no lack of engine oil, the quality of the camshaft rarely fails. 

4. During normal use, the camshaft will also wear. It is a high-frequency, high-pressure, and high-temperature environment.

However, generally, adjusting the screws on the rocker arm can meet the requirements. If the camshaft is replaced, it is necessary to remove the cylinder cover and the valve rocker arm frame, and the timing needs to be re-adjusted. When replacing the camshaft during maintenance, actions should be gentle, the force should be balanced, and the hole of the bearing seat should not be damaged too much.

5. Pedal motorcycles do not have the problem of high speed and low speed. However, it is not advisable to have too low idle speed. This will cause the engine oil to not reach the position, and due to excessive speed fluctuations, the camshaft will shake severely, causing wear and deformation of the bearings.

In addition, the valve clearance should also be adjusted according to the standard.