There are several possible reasons why a motorcycle might stall when pulling in the clutch and slowing down. Here are some common causes to consider:
Idle speed is too low: If the idle speed of the engine is set too low, it may not provide enough power to keep the engine running when the clutch is pulled in and the motorcycle slows down. Adjusting the idle speed to the manufacturer's specifications can help resolve this issue.
Clutch adjustment issues: A poorly adjusted clutch can lead to stalling. If the clutch cable is too loose, it may not fully disengage the clutch plates when the lever is pulled in, causing the engine to stall. Check the clutch cable tension and adjust it according to the motorcycle's manual.
Clutch plate wear: Over time, clutch plates can wear down, reducing their effectiveness in transmitting power. If the clutch plates are excessively worn, they may not fully engage or disengage, resulting in stalling when the clutch is pulled in. In such cases, the clutch plates may need to be inspected and replaced if necessary.
Fuel mixture problems: A lean fuel mixture, where there is not enough fuel in the air-fuel mixture, can cause stalling. This can happen if the carburetor is not properly tuned or if there are issues with the fuel delivery system. Similarly, a clogged fuel filter or a malfunctioning fuel pump can lead to insufficient fuel supply, resulting in stalling when the clutch is pulled in. Cleaning or replacing the fuel filter and ensuring the fuel system is in good working condition can help address these issues.
Engine problems: Stalling can also occur due to underlying engine issues, such as a malfunctioning ignition system, faulty spark plugs, or a dirty air filter. Regular maintenance and inspection of these components can help identify and resolve any problems.
If you're unable to diagnose or fix the issue on your own, it's recommended to consult a qualified motorcycle mechanic who can perform a thorough inspection and provide the necessary repairs or adjustments to address the stalling problem.