Motorcycle Questions? Ask a Mechanic.
Hi and thank you for your question.
There is a cable interlock between the left brake lever and the gear shift handle. If the cable is out of adjustment or has broken, it will not release the lever to allow it to be shifted.
If that cable coming out of the left hand lever is not broken, then it needs to be adjusted. There is an in line adjuster just down the cable from the master cylinder. Pull the lever in 20 mm (measured at the ball end of the lever) and adjust the cable (tighten) until the shift lever will move in both directions from N. After you tighten it so you can shift, then release the lever and confirm that the shift lever will no longer move. Once you have achieved both objectives, the cable is adjusted properly. Lock the cable adjuster lock nut down.