If your motorcycle keeps returning to neutral after shifting from 1st to 2nd gear, it is likely a symptom of a transmission-related issue. Here are a few possible reasons for this problem:
Clutch adjustment: Improper clutch adjustment can prevent the clutch plates from fully disengaging, causing the transmission to remain partially engaged even when you shift gears. This can result in the bike popping back into neutral. Adjusting the clutch cable or hydraulic clutch system may resolve the issue.
Clutch cable or hydraulic clutch issues: If there are problems with the clutch cable or hydraulic clutch system, such as a worn-out cable, loose connections, or insufficient hydraulic fluid, it can affect the clutch's proper functioning. This can lead to incomplete disengagement of the clutch plates and cause the bike to slip back into neutral.
Worn clutch plates: Over time, the clutch plates can wear out, reducing their ability to engage and disengage properly. This can result in incomplete disengagement, causing the bike to shift back to neutral. Replacing the worn clutch plates should resolve the issue.
Transmission issues: There may be problems within the transmission itself, such as worn or damaged gears, bent shift forks, or a faulty shift drum. These issues can affect the smooth engagement of gears and cause the bike to pop back into neutral. If you suspect transmission problems, it's best to have a professional mechanic inspect and diagnose the specific issue.
It's recommended to have a qualified motorcycle mechanic or technician examine your bike if you're experiencing persistent issues with shifting gears. They will be able to diagnose the problem accurately and perform any necessary repairs or adjustments to ensure proper gear engagement.