With the motor idling and in neutral, reach down with your hand, grip the shifter lever and pull it into 1st gear without letting the shifter lever back down.... just hold the lever up firmly and continue to hold it up. Then give it some throttle. If the bikes moves or tries to creep forward, the change clutch needs to be readjusted. If the bike holds still while revving the motor a bit, but begins to move forward as you slowly allow the shifter lever to return, the clutch is adjusted correctly and is working as intended.
Credit goes to retro ^^^