If your Suzuki RG 125 motorcycle starts but only runs for a few moments before shutting down, there could be a few potential issues to investigate. Here are some steps you can take to troubleshoot the problem:
Fuel flow and quality: Ensure that the fuel supply to the carburetor is consistent and free from any obstructions. Check the fuel lines for any clogs, kinks, or leaks. Verify that the fuel filter is clean and not restricting fuel flow. Additionally, make sure you are using fresh, clean fuel that is appropriate for the motorcycle.
Idle adjustment: The idle speed of 1200 RPM you mentioned might be too low, causing the engine to stall. Consult the motorcycle's manual or service guide to locate the idle speed adjustment screw on the carburetor. Gradually increase the idle speed until the engine runs smoothly at idle.
Air intake and filter: Check the air intake system for any blockages or restrictions. Ensure that the air filter is clean and properly installed. A clogged or dirty air filter can disrupt the air-fuel mixture and lead to poor engine performance or stalling.
Carburetor tuning: Even though you've cleaned the carburetor, there may still be issues with its internal components. Ensure that all jets, passages, and floats are clean and functioning properly. Pay close attention to the pilot jet, which affects idle and low-speed performance. If necessary, consider disassembling and thoroughly cleaning the carburetor again or have it professionally serviced.
Ignition system: While you mentioned changing the spark plug, it's worth double-checking that the new spark plug is the correct type and properly gapped. Inspect the ignition coil, spark plug wire, and other related components for any damage or loose connections. If the ignition system is faulty, it can cause intermittent spark and engine shutdown.
Electrical system: Check the battery's condition and ensure it is properly charged. Weak or faulty electrical connections, such as loose or corroded wires, can lead to intermittent power issues. Inspect the wiring harness, fuses, and switches to ensure they are in good condition.
If you've gone through these steps and the issue persists, it might be helpful to consult a motorcycle mechanic or Suzuki specialist who can provide further assistance and diagnostics. They can offer professional guidance and help identify any specific issues with your Suzuki RG 125 that might be causing the engine to stall after a short period of running.