A gear change drum (or shift drum) is a component in a motorcycle's or vehicle’s transmission system responsible for controlling the gear selection process. It works by rotating and engaging various shift forks, which physically move the gears into position. The shift forks are connected to the drum and slide along the transmission’s shafts to engage different gears as the driver shifts. Together, the gear change drum and shift forks ensure smooth and accurate gear changes, playing a vital role in the transmission system's operation.
 

Ref #	PART NUMBER	ITEM NAME	QUANTITY	Destination	Remarks
13107	13107-0843	SHAFT	1
13140	13140-0025	FORK-SHIFT,INPUT	1
13140A	13140-0026	FORK-SHIFT,OUTPUT	2
13141	13141-0568	DRUM-CHANGE	1
13145	13145-0567	CAM-CHANGE DRUM	1
13271	13271-0626	PLATE	1
13280	13280-0875	HOLDER	1
14014	14014-0018	PLATE-POSITION	1
49047	49047-0631	ROD-SHIFT,INPUT	1
49047A	49047-0632	ROD-SHIFT,OUTPUT	1
610	610A0408	ROLLER,4X8	2
92009	92009-1375	SCREW,6X10	2
92045	92045-1122	BEARING-BALL,6805	1
92153	92153-0958	BOLT,FLANGED,6X18	1
92154	92154-0484	BOLT,SOCKET,6X16	1
92154A	92154-0812	BOLT,SOCKET,6X12	1