This is a video on how to replace or how to remove the motor's centric gear without getting off the engine.
The centric teeth of the motorbike are usually removed when changing the pendulum bearing/crutch axle bearing and at the same time when changing the piston handlebar which of course has to get off the engine.
And if the need is only to replace/remove the centric gear, we don't need to get off the engine, and the tool just needs to use a tractor like in this video.
enjoy watching and hopefully useful.