What Causes Abnormal Noise in a Scooter Engine?

[IsabelRose]

The causes of abnormal noise in a scooter engine are as follows: 1. Engine intake pipe leakage: The intake system contains many intake manifolds or valves. Any leakage can allow unintended gas to enter, causing the air-fuel mixture in the intake manifold to become either too rich or too lean, ultimately resulting in intermittent engine shaking or weak idle performance. 2. Fuel system blockage or malfunction: Blockages in the fuel tank vent hole, fuel tank switch, fuel filter, or fuel lines between the tank and carburetor can prevent the engine from receiving the required fuel supply during idle. This leads to a lean air-fuel mixture, reduced engine power output, and idle shaking.