General

The oil feed pump and scavenger (oil return) pump are gear type pumps housed in one pump body and located on rear of gearcase on right side of motorcycle. The feed pump incorporates an automatic bypass valve that reroutes surplus oil (above the amount needed to lubricate the engine) directly to the gearcase. A ball check valve is located ahead of the pressure regulating valve to prevent oil drainage from tank, and to operate the pressure switch.

Under normal operating conditions, the pump is a comparatively trouble free unit. The most common trouble with pump operation is the introduction into the pump of a metal or hard carbon chip. If either gets between the gear teeth, it is possible to shear a key, fracture a gear or break off a gear tooth.

If oil fails to return to the tank, check the scavenger pump gear drive shaft key. When the engine receives no lubrication (oil remains in tank), the drive shaft key on the feed pump drive gear may be sheared. Both conditions together could be caused by shearing of the oil pump (gearcase) drive gear key. In cold weather slush ice formed from moisture condensation in oil may block oil passages and cause any of above troubles.

DISASSEMBLING OIL PUMP (Fig. 3D-1) NOTE

See Fig. 3D-1 or 3D-1A corresponding to pump being worked on.

The oil pump may be removed from the motorcycle as a unit only if the engine is removed from the chassis. The oil pump may be disassembled, piece-by-piece without removing gearcase cover, with engine in chassis as follows:

Disconnect oil lines and oil pressure switch (1) from pump. See Fig. 3D-1B or 3D-1D. Remove nuts and washers or bolts and lock washers (2) from gearcase studs, that hold oil pump cover in place. Remove oil pump cover (3) and gasket (4). Remove lock ring (5), drive gear (6), gear key (7) and idler gear (8). Remove two oil pump body mounting stud nuts (9) and slip pump body (10) off studs and gear drive shaft (11). Remove drive gear (12), key (13), and idler gear (14).

Turn relief valve plug (15) out of pump body and remove relief valve spring (16) and valve (17). Remove check valve spring cover screw (18), valve spring (19) and ball (20). On adjustable chain oiler equipped models, loosen chain oiler adjusting screw lock nut (21) and turn in adjusting screw (22). Count the turns necessary to bottom screw then remove. Bot tom and turn out same number of turns when assembling. Remove chain oiler screw (22A). Oil pump nipples (24) may be turned out of pump cover to facilitate cleaning.

To remove oil pump unit from gearcase with engine removed from chassis, remove gearcase cover screws, cover and gasket. (See "Gearcase Timing Gears".) Turn pinion gear nut off pinion shaft using the special tool, Gear Shaft Nut Socket Wrench, Part No. 94555-55 (left hand thread). Pull pinion gear using Pinion Gear Puller and Installer, Part No. 96830-51, remove key, spring, spacing collar and oil pump pinion shaft gear. Pry spring ring off pump drive gear shaft and remove drive gear and key. Remove pump body nuts and bolts (2 and 9) and slip pump with drive shaft (11) out of gearcase. Pump is then disassembled as above.

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