If your SYM automatic 125cc motorcycle is not starting, and the battery has been ruled out as the issue, there could be several other potential causes. Here are a few possibilities to consider:
Fuel-related issues: Check if there is enough fuel in the tank. It's possible that the fuel level is too low for the motorcycle to start. Additionally, ensure that the fuel valve (if present) is open, allowing fuel to flow to the engine. If the fuel is old or contaminated, it may be worth draining the old fuel and refilling with fresh fuel.
Ignition system problems: The ignition system may be malfunctioning, preventing the spark plugs from firing properly. Check if the spark plugs are clean and in good condition. If they are fouled or worn out, they may need to be replaced. Additionally, inspect the ignition coils, spark plug wires, and the associated wiring for any signs of damage or loose connections.
Carburetor issues: If your motorcycle has a carburetor, it may be clogged or dirty, affecting the fuel-air mixture and preventing the engine from starting. Cleaning the carburetor or having it professionally serviced may help resolve the issue.
Faulty starter motor or starter relay: The starter motor or starter relay may be faulty, preventing the engine from cranking. If you hear a clicking sound when attempting to start the motorcycle, it could indicate a problem with the starter relay. A professional inspection or testing may be required to determine if these components need repair or replacement.
Electrical system problems: There may be an issue with other electrical components such as the ignition switch, kill switch, or wiring. Inspect these components for any signs of damage or loose connections. Ensure that all switches are in the correct position and that the wiring is secure.
Engine or mechanical issues: If all the above possibilities have been checked and ruled out, there may be underlying engine or mechanical problems that require professional diagnosis and repair. This could include issues with the valves, compression, or other internal components.
It's worth noting that diagnosing and repairing motorcycle issues can be complex, and it may be beneficial to consult a qualified mechanic or SYM dealership to properly diagnose and resolve the problem. They have the expertise and specialized tools to identify and fix the specific issue with your motorcycle.