If a motorcycle is parked in gear and the foot is off the clutch/brake, but it still rolls off, there are a few possible reasons for this:
Insufficient Clutch Engagement: If the clutch is not fully disengaging, even though the lever or pedal is released, there may be an issue with the clutch system. This could be due to a worn clutch cable, a misadjusted clutch lever, or a problem with the clutch plates. In such cases, the clutch is not fully disengaging, and power from the engine is still being transmitted to the wheels, causing the motorcycle to roll.
Clutch Drag: Clutch drag occurs when the clutch plates do not fully separate when the clutch lever is released. This can happen due to incorrect clutch adjustment, worn or warped clutch plates, or a malfunctioning clutch release mechanism. Clutch drag can lead to the transmission being partially engaged, resulting in the motorcycle rolling despite being in gear.
Faulty Transmission Components: Internal issues within the transmission can cause the motorcycle to roll off unexpectedly. Problems such as worn gears, damaged shift forks, or a malfunctioning shift drum can prevent the transmission from fully engaging the selected gear, allowing the motorcycle to roll.
Hydraulic Clutch Issues: Motorcycles equipped with hydraulic clutches may experience problems such as air in the clutch line or a faulty master or slave cylinder. These issues can affect the proper functioning of the clutch and lead to incomplete disengagement, causing the motorcycle to roll.
If you're experiencing this issue with your motorcycle, it's important to have it inspected and repaired by a qualified mechanic. They can diagnose the specific problem and carry out the necessary repairs or adjustments to ensure the clutch system and transmission are functioning properly. Regular maintenance and inspections are crucial to catch any potential issues early and prevent safety hazards while riding.