Oil Pump


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 relief valve that re-routes surplus oil (above the amount needed to lubricate the engine) directly to the oil tank. A check valve ball 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 drive gear key (7). 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, ice slush formed from moisture condensation in oil may block oil passages and cause any of above troubles.


The oil pump may be removed from the motorcycle as a unit after gearcase cover is removed. 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. Remove 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),

Bolts And Gear Illustration


Oil pressure switch


Oil pump body mounting


Check valve spring cover screw


Cover stud nut or bolt

stud nuts and washers (2)


Check valve spring

and washer


Oil pump body


Check valve ball


Oil pump cover


Oil pump gear drive shaft


Chain oiler adjusting screw


Cover gasket


Drive gear


Oil line elbow and nipple (2)


Lock ring


Gear key


Chain oiler pipe


Drive gear


Idler gear


Body gasket


Gear key


Relief valve plug and washer


Idler gear shift


Idler gear


Relief valve spring


Plug and gasket


Relief valve spring plunger

Figure 3-19. Oil Pump — Exploded View

Figure 3-19. Oil Pump — Exploded View

Figure 3-20. Hose Clamp Connection gear key (7) and idler gear (8). Loosen relief valve plug (15) and check valve spring cover screw (18). 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). Turn in adjusting screw (21). Count the turns necessary to bottom screw, then remove. Bottom and turn out same number of turns when assembling. Oil pump elbows (22) may be turned out of pump cover to facilitate cleaning.

To remove oil pump unit from gearcase with gearcase cover removed, remove ignition timer parts, gearcase cover screws, cover and gasket. (See "Gearcase Timing Gears.") Use a right angle lock ring pliers to remove lock ring from groove in 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.


Thoroughly clean all parts in cleaning solvent and blow pump body passages clear with compressed air. Inspect valves and valve seats for pitting and wear. Replace pump having worn or damaged valve seat. Inspect keys and key-ways. Inspect scavenger and feed pump gear teeth for gouging or cracking caused by foreign materials going through pump. Pump shafts and bushings normally last for lifetime of engine.


Oil pump is assembled in reverse order of disassembly. Do not mix gears and keys - return to correct location. Oil pump gaskets should always be replaced. Use only "factory made" gaskets. Lock rings are often damaged when removing them. It is advisable to install a new lock ring using a lock ring pliers when assembling pump. Make sure ring is engaged and seated in retaining groove.

If pump is assembled with plastic gaskets, bolts and nuts must be drawn down evenly to approximately 45 in-Ibs, but no more than 50 in-lbs torque (4 to 5 ft-lbs). If pump is assembled with paper gaskets, tighten bolts and nuts to 90-100 in-lbs torque.

This is important because the oil pump cover gasket and body gasket if overtightened, will be squeezed out of place and eliminate pump gear side clearance which may seize and damage the pump parts.

If leakage problem exists, disassemble pump and inspect all gasket surfaces making sure they are flat and smooth. Install new gaskets and reassemble pump, tightening four bolts and two nuts as specified.

Oil hose connections have one piece band type clamps and must be replaced each time hoses are connected. Use Hose

Shovelhead Oil Pump Relief Valve Plug

Figure 3-21. Oil Pump and Connecting Lines

1. Oil supply line from tank

2. Oil return line to tank

3. Vent line to oil tank

4. Vent line to chain housing

5. Crankcase breather hose

6. Front chain oiler line to chain housing

7. Tappet oil screen plug

8. Rear chain oiler adjusting screw

9. Rear chain oiler line

10. Chain housing return line

11. Oil pressure switch

Clamp Tool Part No. 97087-65 to squeeze clamps tight as shown in figure 3-20.



The tappet assembly consists of tappet, roller and hydraulic unit. The tappet and roller, under compression force from valve spring, follow the surface of the revolving cam. The linear motion produced is transmitted to the valve stem by the hydraulic unit, push rod and rocker arm. The hydraulic unit contains a piston or plunger and cylinder plus a ball check valve which allow the unit to pump itself full of engine oil to take up all play in the entire valve train.

When hydraulic units are functioning properly the assembly operates with no tappet clearance. The units automatically compensate for heat expansion to maintain a no-clearance condition.

It is normal for tappets to click when engine is started after standing for some time. Hydraulic units have a definite "leak down" rate which permits the oil in the hydraulic unit cylinder to escape. This is necessary to allow units to compensate for various expansion conditions of parts and still maintain no-clearance operation. Hydraulic units are functioning properly if they become quiet after a few minutes of engine operation.


If engine cylinder head is not disassembled, remove push rod cover spring cap retainer. Lift push rod covers and retract push rod adjusting screw until push rod may be lifted out of ball sockets.

Remove tappet and guide assembly. Be careful to avoid dropping a tappet through guide mounting hole and into gearcase. Slip push rod cover cork washers (3) or O-ring (3A) out of top of tappet guide (4). Pull tappet and roller (5) out bottom of tappet guide and remove tappet guide gasket (6).

Remove tappet and guide assembly. Be careful to avoid dropping a tappet through guide mounting hole and into gearcase. Slip push rod cover cork washers (3) out of top of tappet guide (4). Pull tappet and roller (5) out bottom of tappet guide and remove tappet guide gasket (6).


Wash all parts except hydraulic units and gaskets in grease solvent. Hydraulic unit parts are selectively fitted and may not be interchanged so they must be individually and separately washed. Twist and pull hydraulic piston and spring from cylinder and wash parts.

Blow out oil passages in tappets, tappet guides and hydraulic units with compressed air. Insert a length of wire into oil channel openings in tappet guide to make sure passages are open. Air dry all parts.

1. Tappet guide screw (4)

2. Hydraulic unit (2)

3. Cork washer (2) (1978 to early 1979) 3A. O-ring (2) (Late 1979 to 1980)

4. Tappet guide

5. Tappet and roller assembly (2)

6. Tappet guide gasket

Figure 3-22. Tappet Assembly — Exploded View

Examine cams through tappet guide holes in gearcase for nicked, grooved or chipped condition. Examine tappet-guide matching surfaces for scuffing or grooving.

When tappet fit in "guide exceeds maximum tolerance shown in "Engine Specifications" by 0.001 in. or more, replace worn parts. If roller is loose, force out pin on arbor press, insert new parts and peen or stake pin ends.

Check roller end clearance. Replace all units exceeding tolerances listed in specifications.


Hydraulic units may be checked as follows: Wash and air dry piston and cylinder. Blow out cylinder from bottom to make sure ball and seat are dry. Insert piston in cylinder. Hold in an upright position and press down piston, until spring touches cylinder, without covering hole in bottom of cylinder. Hold for count of 6 and release. If piston bounces back, unit is serviceable. If piston does not bounce back, cover hole in bottom of cylinder and repeat above process. If piston does not bounce back, unit is worn and must be replaced. If piston bounces back, ball is not seating, and unit should be replaced. Before replacing hydraulic units, check possibility of plugged or partially plugged screen under large cap screw (7, Figure 3-21) located near rear tappet guide. Remove screen as described in "Disassembling Gearcase," and clean or replace it if it is dirty.

Temperature Control Turbine Bypass Valve
Figure 3-23. Inserting Tappets in Guide


Assemble tappets as follows: Slip tappets (5) into guide (4) so flat surfaces on tappets are toward center of guide as shown in figure 3-23. If flat surfaces with holes are not toward center of guide, engine oil will not feed across and one hydraulic unit cannot fill with oil. Assemble tappet guide gasket dry and insert tappet assembly in place on gearcase, holding tappets in place with thumb and forefinger as when unit was removed.

Assemble push rod cover cork washers or O-rings, push rod hydraulic units and tappet guide screws. Torque tappet guide screws to 10 ft-lbs.

Assemble remainder of push rod assembly in same order disassembled.

Adjust tappet clearance as described in "Cylinder Head."

Shafts run in bushings except the crankcase side of the cam shaft which operates in a needle roller bearing.


Before disassembling gearcase, it is advisable to remove push rods, tappets, push rod hydraulic units and tappet guides as described in "Disassembling Tappets."

1. Remove oil screen cap (1), O-ring (2), screen spring (3) and screen (4).

2. Remove ignition system components as described in Section 5.

3. Remove gearcase cover screws (13,14 and 15).

4. Tap gearcase cover with wood or rawhide mallet to loosen and remove gear cover (16) and gearcase cover gasket (17).

5. Remove breather gear spacing washer (18) and breather gear (19).

6. Remove cam gear (20), spacing washer (21), and thrust washer (22).

7. Remove pinion gear shaft nut (23) which has a left-hand thread. Use Gear Shaft Nut Socket Wrench, Part No. 94555-55A. Pull pinion gear (24) using Pinion Gear Puller and Installer, Part No. 96830-51 as shown in Figure 3-25. Tool has lefthand threads.

8. Remove key (25), gear shaft pinion spacer (26), oil pump pinion shaft gear (27) and key (28).

9. Use a lock ring pliers such as Snap-On No. Pr129A and remove oil pump drive gear shaft lock ring (29), drive gear (30) and drive gear key (31).

10. If necessary, remove oil pump stud nuts and washers and remove oil pump from gearcase. See "Dissasembling Oil Pump."



The gearcase, located on the right side of the engine crank-case, contains a train of gears which transmit engine power to the cam shaft and ignition timer, crankcase breather and oil pump. The gearcase is lubricated with engine oil through the by-pass circulatory system and through the breather valve from engine crankcase.


1. Wash and air-dry all parts. Wash inside of case. If crankcase is to be disassembled, wash parts after complete disassembly. If it is not to be repaired, be careful to get no grease or solvent into crankcase when washing gearcase.


Image Tappet Screen 1998 Fxdwg

1. Oil screen cap

3. Oil screen spring

4. Oil screen

5. Ignition timer cover screws (2)

6. Ignition timer cover

7. Ignition module

8. Trigger rotor bolt

9. Timer plate screw and lockwasher (2)

10. Timer plate

11. Trigger rotor

12. Timer advance assembly

16. Gear cover

17. Gear cover gasket

18. Thrust washer

19. Breather gear

20. Cam gear

21. Cam gear spacing washer

22. Cam gear thrust washer

23. Gear shaft nut

24. Pinion gear

25. Pinion gear key

26. Pinion gear spacer

27. Oil pump pinion shaft gear

28. Oil pump pinion shaft gear key

29. Oil pump drive gear lock ring

30. Oil pump drive gear

31. Oil pump drive gear key

32. Gear cover camshaft bushing

33. Gear cover pinion shaft bushing

34. Camshaft oil seal

35. Camshaft needle bearing

37. Wire clip

38. Welch plug

39. Oil line fitting

40. Oil pump shaft

Note: 1979 and earlier ignition system components are shown in this illustration. 1980 and later components are shown in Figure 5-22A.

Figure 3-24. Gearcase — Exploded View

Figure 3-25. Pulling Pinion Gear

2. Inspect oil screen (4) carefully to make sure mesh is open. Holding screen to light is not an absolute check. It is possible for oil screen to be plugged or partially plugged with tiny lint-like fibers and still permit light to pass. Replace plugged or partially plugged screen.

3. Inspect cam shaft and pinion shaft bushings (32 and 33) in gearcase cover for pitting, scuffing and grooving. Determine amount of pinion and cam shaft wear in cover bushings. If it exceeds maximum tolerance shown in "Engine Specifications," by 0.001 in., install new bushings.

4. Inspect cam gear oil seal (34) in cover to see that lip is in good condition.

5. Attach dial indicator to gearcase cover mounting screw hole and determine amount of pinion shaft play in right main roller bearing. When tolerance in "Engine Specifications" is exceeded by 0.001 in., bearings should be replaced.

6. Inspect needle bearing (35) for wear, broken or gouged bearings. If end of cam shaft shows any appreciable wear (0.003 in. or more), needle bearing is probably worn to a point where replacement of bearing and cam shaft are advisable.

7. Needle bearing can be removed and installed in crankcase without disassembling crankcase with Puller Tool, Part No. 95760-69 as shown in figure 3-29. Press needle roller bearing into crankcase with Tool, Part No. 97272-60 as shown in figure 3-29. Press from heavier end having the manufacturer's name only. Pressing from opposite end will crush roller race and bind rollers. Pinion shaft main roller bearing may be replaced only when crankcase is disassembled (see "Disassembling Crankcase").

8. Inspect gears for wear. Assemble pinion and cam gears to respective positions in gearcase. Omit cam gear end spacer for the purpose of checking gear mesh. Attach cover with at least 3 cover screws. Mesh is considered ideal when no play between gears can be felt and cam gear can be moved back and forth along shaft axis with slight drag.

Basement Pump
Figure 3-26. Removing Pinion Shaft Cover Bushing


Remove pinion shaft cover bushing using Puller Tool, Part No. 95760-69 as shown in figure 3-26.

Install new pinion gear shaft bushing (33) in hole in cover as follows:

Position bushing in cover so flat on bushing is in line with oil hole in cover. Press in bushing on arbor press until top of bushing is flush with cast bushing boss on cover. Locate and center punch new dowel pin location 1/8 in. or more from original location. Drill No. 31 hole 3/16 in. deep. Press in bushing until it bottoms on shoulder in cover boss hole. Continue drilling dowel pin hole to depth of 9/32 in. from top of bushing. Drive in new dowel pin and carefully peen edges of hole to lock pin in place.

To replace cam shaft cover bushing (32), proceed as follows:

Use Puller Tool, Part No. 95760-69, to extract old bushing. Make a mark on outside of bushing boss to locate original dowel pin hole. Press in new bushing with arbor press until shoulder is against cover boss. Locate new dowel pin hole at least 1/8 in. from original hole, centerpunch and drill No. 31 hole exactly 9/32 in. deep. Drive in new dowel pin and peen bushing edges over dowel to secure it.

Drill lubrication oil hole through wall of bushing with 5/32 in. drill, using oil hole in bushing boss as a drill guide.

Pinion shaft and cam shaft bushings must be line reamed to remove burrs and irregularities from hole and to insure perfect alignment. If crankcase is not disassembled, use another right crankcase side. Fasten cover in place with at least three screws.

To ream pinion shaft bushing, insert reamer pilot in right crankcase roller race as shown in figure 3-27. Insert 9/16 in. Pinion Shaft Cover Bushing Reamer, Part No. 94805-57 through pilot and push into cover bushing until it bottoms, then give reamer one complete turn to size bushing.

Rotate reamer the same direction (clockwise) during extraction.

To ream cam gear cover bushing, use a 1 in. expansion reamer and ream to 1.003/1.002 in. diameter.


1. Before assembling gear train, determine amount of end play in breather gear as follows: Assemble breather gear and old compressed dry cover gasket to gearcase. Select thrust washer (use washer disassembled unless it is known to give incorrect spacing) and position on end of breather gear. Place a steel straightedge across gearcase at spacer. With thickness gauge, measure distance between straightedge and spacer. If new gasket is used subtract 0.006 in. (amount gasket will compress) from this figure to determine gear end play. An end play tolerance of 0.001 to 0.005 in. is correct. If end play exceeds maximum, insert thicker spacer. Breather valve and gear spacer washers are available 0.110, 0.115, 0.120, 0.125, 0.130, 0.135, 0.140, 0.145 in. thick.

2. To establish proper cam gear end play, install thrust washer, spacing washer and cam gear. Position cover gasket and secure cover with at least four screws. Measure cam shaft end play between cam gear and cover bushing with thickness gauge through tappet guide hole in gear-case. End play should be from 0.001 to 0.005 in. If measurement is under or over tolerance, remove cover and replace spacing washer with one to give suitable clearance. Cam gear spacing washers are available 0.050,0.055,0.060, 0.065, 0.070, 0.075, 0.080, 0.085, 0.090, 0.095 in. thick.

3. Make final gearcase assembly including all parts in reverse order of disassembly order. Make sure that

Scooter Timing Marks
Figure 3-28. Timing Gears with Timing Marks Aligned

chamfer on oil pump pinion shaft gear (27) faces toward the inside. Tighten pinion gear shaft nut (23, Figure 3-24) to 35 to 45 ft-lbs. Make sure that gear shaft pinion spacer (26) has noticeable end play, indicating that the

Figure 3-27. Line Reaming Cover Bushing

Figure 3-29. Removing and Installing Cam Gear Needle Bearing

Figure 3-27. Line Reaming Cover Bushing pinion gear is properiy seaiea on ine snari taper. Breather, cam and pinion gears contain timing marks which must be aligned or matched as shown in Figure 3-28. Rotate gear train and note if it revolves freely. A bind indicates gears are meshed too tightly.


Pinion gears and cam gears are color coded according to their pitch diameters. When replacing only one of these gears, it is advisable to replace it with a gear having the same color code. If gears are not matched according to their color, lifter noise or gear whine may result.

n. Apply a coat ot non-hardening gasket sealer to crank case and cover gasket surface. Position new cover gaske-and secure cover with all cover screws. Pour about 1/4 pirn of engine oil over gears to provide initial lubrication before securing cover.

5. Assemble remainder of gearcase, and ignition timei in reverse of order removed. When assembling ignitior timer, set sensor air gap and ignition timing as describec in "Ignition System" Section 5.

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