Disassembling Crankcase

1. Remove cylinder heads as described in "Disassembling Cylinder Head."

2. Remove cylinders as described in "Disassembling Cylinder and Piston."

3. Remove gearcase parts as described in "Disassembling Gearcase." Check flywheel end play as described previously.

Refer to figure 3-30 and proceed as follows:

4. Remove crankcase bolts and studs (1, 2, 3, 4, 5), It is necessary to remove only one stud nut and slip stud and other nut out opposite side of crankcase.

Refer to figure 3-31 and continue disassembly:

5. Position crankcase with gearcase (right side) up. Tap crankcase with rawhide or soft metal mallet to loosen top half. Lift right crankcase half (1) off pinion shaft main bearings. Remove spiral lock ring (2) from pinion shaft with tip of screwdriver. Lift bearing washers (3 and 5) with bearings and bearing retainers (4) off pinion shaft.

2. Crankcase stud, 5/16 x

5 in. (right center)

3. Crankcase stud, 5/16 x

4. Crankcase stud, 5/16 x 5-7/16 in. (2) (top and top right)

5. Crankcase stud, 11/32 x 5-13/16 in. (2) (left and right bottom)

Figure 3-30. Crankcase Studs — Exploded View

6. Mount flywheel and left case assembly on press table supporting case on parallel bars (figure 3-33) and press on end of sprocket shaft with arbor press until flywheel assembly (8) drops out. Remove seal (7), freeing sprocket side bearing half (9), spacer (6) and spacer ¡10).

7. If left main bearing is to be replaced, tap out bearing races (11 and 13) from opposite sides of crankcase hole, using a brass drift and hammer. Remove lock ring-spacer (12) using a pin punch or similar tool. Rotate lock ring in groove so that one edge covers oil hole. Insert tool into oil hole with tapered end underneath lock ring. Tap on tool to force one end out of groove as shown in Figure 3-3^. Starting at this free end, push ring out of bearing bore.

8. If flywheels are to be disassembled, grip pinion shaft in vise and pull bearing (15) from sprocket shaft using claw puller and wedge attachment. Place wedge halves behind bearing and pull bearing off by tightening roller screw against sprocket shaft center as shown in Figure 3-35. Keep bearings in a set with proper bearing outer races.



1. Grip pinion shaft in copper covered vise jaws so shafts are in vertical position. Insert a rod about 5 in. long and 1/2 in. in diameter through holes in flywheels to keep them from turning. Remove crank pin nut (1) with Flywheel Nut Wrench Part No. 94546-41. Strike left flywheel with soft metal mallet at about 90 degrees from crank pin hole on wheel periphery to loosen. Lift left flywheel (2) off crank pin.

2. Hold down bearing assembly with a short length of pipe or tubing so connecting rods (3) may be slipped off bearings. Remove bearings (4). Hold together in set until bearings are washed and refitted to crank pin.

3. Remove gear shaft nut (5). Tap pinion shaft (7) out of flywheel (6). Remove key (8) from shaft.

Spiralock Snap Ring

1. Right crankcase half

2. Spiral lock ring

3. Bearing washer (2)

4. Bearings and retainer

5. Bearing washer (see item 3)

6. Sprocket shaft spacer

7. Sprocket shaft bearing seal

8. Flywheel and rod assembly

9. Sprocket bearing half

10. Bearing inner spacer

11. Bearing outer race

12. Outer race snap ring

13. Bearing outer race

14. Left crankcase half

15. Sprocket bearing half

16. Pinion shaft bearing race lock screw (2)

17. Pinion shaft bearing race

1. Right crankcase half

2. Spiral lock ring

3. Bearing washer (2)

4. Bearings and retainer

5. Bearing washer (see item 3)

6. Sprocket shaft spacer

7. Sprocket shaft bearing seal

8. Flywheel and rod assembly

9. Sprocket bearing half

10. Bearing inner spacer

11. Bearing outer race

12. Outer race snap ring

13. Bearing outer race

14. Left crankcase half

15. Sprocket bearing half

16. Pinion shaft bearing race lock screw (2)

17. Pinion shaft bearing race

Note: Keep parts 9, 10, 11, 12, 13 and 15 as a set. Do not transpose or interchange parts.

Figure 3-31. Crankcase — Exploded View

6. Sprocket shaft bearing spacer

7. Bearing seal

8. Flywheel and rod assembly

9. Sprocket bearing outside half

10. Bearing inner race spacer

11. Bearing outer race

12. Bearing outer race lock ring

13. Bearing outer race

14. Left crankcase half

15. Sprocket bearing inside half

Figure 3-32. Sprocket Shaft Bearing Assembly — Section View

4. Clamp crank pin in vise. Remove crank pin nut (9). Tap crank pin (10) out of flywheel and remove key (11).

5. Grip sprocket shaft in vise and remove sprocket shaft nut (12). Use Snap-On Socket, Part No. S6202, for 1-5/8 in. hex nut. Remove sprocket shaft (13) by tapping it out of flywheel.


1. Wash all parts in grease solvent and blow dry with compressed air. Examine crank pin for wear, grooving and pitting. If the surface is at all worn, replace with new pin. Examine flywheel washer (14 and 15). If either washer is worn and grooved, it should be replaced.

Figure 3-33. Pressing Flywheels Out of Crankcase.
Pitting And Gouging Shaft
Figure 3-34. Removing Lock Ring

2. Examine connecting rod lower races. If they appear slightly grooved or shouldered where edge of bearing rollers ride, they may be lapped out and oversize bearing rollers installed. If they appear badly worn, grooved or pitted, new rods should be installed, preferably as an assembly with new bearings and crankpin.

3. Examine pinion shaft and right crankcase bearing race (see 17, figure 3-31) for pitting, grooving and gouging at point where right main roller bearings ride. A shaft that is worn must be replaced. If bushing is worn beyond repair, replace as described in "Truing and Sizing Pinion Shaft Main Bearing."

4. Examine sprocket shaft outer races for wear, grooving, and pitting. Examine bearing rollers for wear, pitting, grooving and heat discoloration. The sprocket shaft Timken tapered roller bearings are manufactured in selectively fitted sets. The same serial number appears on all parts. If any part is unusable, the complete set must be replaced.

Figure 3-35. Pulling Bearing from Sprocket Shaft


Replace worn flywheel washers as follows:

1. Washer is a close fit in recess in flywheel and is secured originally by punching flywheel metal tight against the washer at several points. It is usually necessary to drill a small hole (1/8 in. or smaller) at the outer edge of the washer to permit getting a pointed tool underneath to pry it out. The hole is drilled only slightly deeper than the thickness of the washer to avoid removing more metal than necessary.

2. Before installing new washer, scrape outer edge of washer recess where metal was punched against it so new washer may seat fully against recess bottom. If washer does not seat fully, forked rod is not likely to have necessary clearance for side play.


1. Connecting rod lower races that are likely to clean up within the range of oversize bearing rollers and are otherwise in serviceable condition, should be trued and sized with Connecting Rod Lapping Arbor, Part No. 96740-36 as shown in figure 3-37.

2. Turn lap in lathe at 150 to 200 rpm. Adjust lap by means of adjusting nut to a dragging but free fit in rod race. Clean lap before using, then apply fine lapping compound (No. 220 grit grinding compound mixed with oil) to lap. A loose lap will "bell mouth" bearing race so it must be kept adjusted at all times. To avoid grooving or tapering

1. Crank pin nut

2. Left flywheel

3. Connecting rods (one forked, one single end)

4. Bearing rollers and retainers

5. Pinion shaft nut

6. Right flywheel

7. Pinion shaft

8. Pinion shaft key

9. Crank pin nut

10. Crank pin

11. Crank pin key

12. Sprocket shaft nut

13. Sprocket shaft

14. Flywheel washer

15. Flywheel washer

Figure 3-36. Flywheel Assembly — Exploded View





Sprocket Shaft Bearing Nut


Figure 3-37. Lapping Connecting Rod Bearing Race


Figure 3-37. Lapping Connecting Rod Bearing Race lapped surface in rod, work rod back and forth the full length of the lap holding rod as near race end as possible. Lap rods individually.

3. When rods are lapped true and all traces of pit marks or grooving are cleaned up, wash rods and blow dry. Surface should have a soft velvety appearance and be free of shiny spots.


Oversize rollers are available in 0.0002, 0.0004, 0.0006,

0.0008 and 0.0010 in. oversize.

There are two ways to determine which oversize rollers to use that will result in properly fitted bearings if applied correctly.

1. Use a micrometer to measure the outside diameter of the crank pin at its center. Use an inside micrometer or telescoping hole gauge to measure the inside diameter of the rod races. Subtract the diameter of the crank pin from the inside diameter of the bearing race. Subtract from this ■figure the standard allowance for bearing running fit size. This answer, divided by two will give proper roller size. To find oversize amount of bearing, subtract from this figure the diameter of a standard roller.


The rod bearing race measures 1.6263 in. after lapping and truing. The crank pin is slightly worn and measures 1.2485 in. Subtract 1.2485 in. from 1.6263 in. The answer, 0.3778 in., represents the diameters of both rollers (one on each side) plus clearance for running fit. Subtract minimum clearance for running fit (0.001 in.). The answer, 0.3768 in., is then divided by two to get the diameter of each oversize roller. In this case it would be 0.1884 in. To find how much oversize each roller must be, subtract from this figure the diameter of a standard roller, or 0.1875 in. Rollers must be 0.0008 in. oversize.

2. Install any new set of oversize rollers to bearing races and position on crank pin. Slip rods over bearings. If they will not fit, it is obvious rollers are too large and a smaller size must be tried. If they fit and spin freely, install a larger set of rollers. Try various roller sizes until the rods will turn with a very slight drag. This is a plug fit. Determining running fit is merely a matter of subtracting one half the desired running fit clearance (0.0075 in.) from the roller size.

It may be easier to gauge a plug fit as follows:

Fit any size rollers into races. Position bearings in rods. Support rods and bearings with left hand. Drop crank pin (not attached to flywheel) through crank pin hole. Plug fit has been achieved when crank pin will slide slowly through hole from its own weight. Running fit is then determined by subtracting one half running clearance from oversize of rollers to make plug fit.


After correct connecting rod bearing fit has been attained, clean and assemble parts as follows:

NOTE: Use Loctite RC-40 on all tapers, and Harley-Davidson Wick N' Lock (green), Part No. 99627-77 on all threads.

1. Wipe all tapers perfectly clean and free of oil. Assemble sprocket shaft (13) to left flywheel (2). See "Engine Specifications" for proper torque. Assemble pinion shaft (7) and crank pin (10) to right flywheel (6) making sure that keys (8, 11) are in proper position. See "Engine Specifications" for proper torque. Check to

Figure 3-39. Correcting Flywheel Alignment

Crankshaft Oil Passages

make sure oil passages through pinion shaft, right flywheel and crank pin are clear by blowing compressed air into hole near end of pinion shaft.

2. Position right flywheel assembly in vise, crank pin up. Wipe crank pin taper clean. Slip bearings and connecting rods over crank pin with forked rod to rear cylinder. Wipe crank pin hole in left flywheel clean and dry. Install left flywheel and tighten nut lightly. Hold steel straightedge along outer face of wheel rims at 90 degrees from crank pin as shown in figure 3-38. Tap outer rim of top wheel until wheels are concentric. Tighten nut, recheck with straightedge at frequent intervals. Use soft metal hammer to realign wheels. To prevent flywheel assembly from turning in vise while tightening nut, insert a rod 5 in. long and about 1/2 in. in diameter through holes in flywheels and between vise jaws so that rod bears against some part of the vise.

3. When nut is fairly tight, install flywheel assembly in Flywheel Truing Device, Part No. 96650-30. Adjust so centers are snug. Wheels must turn freely but shafts may not be loose in centers. If flywheel assembly is either loose or squeezed, indicators will not indicate accurately. Adjust indicators to take reading as near to flywheels as possible, so pointers read at about the middle of the scales.

4. Turn flywheels slowly and observe the movement of indicator pointers. Movement toward flywheels indicate high points of shafts. Find highest point of each shaft and chalk-mark flywheel rims at those points. Remove flywheel from stand and make corrections as follows:

5. See Figure 3-39. Flywheels may be out of true three ways, A, B and C, or a combination of two of the three ways.

6. When wheels are both out of true as indicated in "A," tighten a C-clamp on rims of wheels opposite crank pin and lightly tap the rim at the crank pin with lead or copper mallet.

Figure 3-39. Correcting Flywheel Alignment

7. When wheels are both out of true as indicated in "B," drive a hardwood wedge between the wheels opposite the crank pin and lightly tap the rims near the crank pins with a mallet.

8. When wheels are out of true as indicated in "C," strike the rim of the wheel a firm blow at about 90 degrees from crank pin on high side (see figure 3-40).

9. When wheels are out of true in a combination of any of conditions shown, correct A or B first, tapping rim of offending wheel only, and then correct condition C.

10. The number of blows required and how hard they should be struck depends on how far shafts are out of true and how tight nuts are drawn. Never strike wheels near crank pin. This could result in a broken crank pin. Never hit on the pinion side.

Flywheel Truing Stands
Figure 3-40. Truing Flywheels on Truing Stand


Flywheel Truing Stands
Figure 3-41. Checking Connecting Rod Sideplay

11. Readjust centers, revolve wheels and take reading from indicator. Repeat truing operation until indicated run out does not exceed 0.001 in. (each graduation on indicator is 0.002 in.).

12. If it is impossible to true wheels, check for a cracked flywheel, damaged or enlarged tapered hole, or a sprocket or pinion shaft worn out of round at surface where indicator reading is being taken. When wheels are true, position in vise and draw crank pin nuts very tight using Crank Pin and Flywheel Nut Wrench, Part No. 94546-41. Use torque wrench to finish tightening to 200 ft-lbs torque. Check connecting rod side play with thickness gauge as shown in figure 3-41. If it is greater than tolerance shown in "Engine Specifications," draw up crank pin nuts until within tolerance. Insufficient play between rods and flywheel face is caused by one of the following conditions:

a. Flywheels and crank pin assembled with oil on tapers and nuts over-tightened. Disassemble, clean, reassemble.

b. New flywheel washers installed and not fully seated. Disassemble, inspect, replace deepest seating flywheel or exchange crank pin. As last resort, grind down width of forked rod.

c. Taper holes enlarged as a result of having been taken apart several times. Replace both flywheels.

d. Cracked flywheel at tapered hole. Replace both flywheels.

If sides of forked rod are ground to get desired clearance, backs of bearing retainers must be ground down to remain narrower than width of female rod.

After rod sideplay is checked and adjusted, crank pin nut tightened to specified torque, and lock plate and screw installed, again recheck wheel trueness on truing device. Correct any run-out as above.

Figure 3-42. Main Bearing Lapping Tools


Before fitting new pinion shaft main bearings, lap bearing race in crankcase to true it and remove traces of wear shoulder at sides of roller paths. Using Crankcase Main Bearing Lap, Part No. 96710-40 consisting of lapping shaft, handle, lapping arbor and guide sleeve (figure 3-42).

A race that is worn beyond limits of oversize bearings must be replaced. To remove worn bearing race, remove two bearing race lock screws (16, figure 3-31) from inside of case. Heat case to 275 - 300 degrees F. Heating expands case and makes it possible to remove bearing race using less force. Press worn race (17, figure 3-31) out and new race in. New race must be lapped slightly to true and align with left case bearing, and to attain a size compatible with roller sizes available.


Secure right and left crankcase halves with three crankcase stud bolts (top center and bottom left and right). The sprocket shaft bearing outer races and large spacer must be installed in left crankcase.

Arbor Shaft And Bearings
Figure 3-43. Lapping Pinion Shaft Main Bearing Race

Assemble lapping arbor to lapping handle and assemble guide sleeve to sprocket shaft bearing bushing. Sleeves for use with tapered bearing, are assembled to case with bearings and small spacer collar. Turn sleeve parts finger tight.

Insert lap shaft with arbor assembled through pinion bearing bushing and into guide sleeve. Tighten arbor expansion collars using a length of 5/32 in. rod as spanner until arbor begins to drag. Do not adjust arbor snug in bushing or bushing will "bell," a condition where hole is larger at ends than it is in the center.

Withdraw arbor far enough to coat lightly with fine lapping compound. Do not apply a heavy coat. Reposition lap in bushing and turn handle at moderate hand speed. Work lap back and forth in bushing as it is revolved to avoid grooving and tapering.

At frequent intervals, remove lap from crankcase, wash and inspect bushing. Lapping is completed when entire bushing surface has a dull, satin finish rather than a glossy, smooth appearance. If necessary, flush off lap in cleaning solvent, air dry and apply fresh, light coat of fine lapping compound.


one half the desired running fit clearance from the size oi the plug fit rollers.


Running fit clearance is 0.0005 to 0.001 in. loose. See "Engine Specifications," Section 3. If a plug fit was achieved with 0.0006 in. oversize rollers, subtract one half running fit clearance from plug fit roller oversize. Use figure representing middle or average of tolerance span, 0.00075 or 0.0008 in. One half the average of tolerance (0.0004 in.), subtracted from roller oversize (0.0006 in.), indicates that 0.0002 in. oversize rollers should be usee to produce a suitable running fit.

Oversize rollers are available in 0.0002, 0.0004, 0.0006, 0.0008 and 0.001 in. sizes. All calculations should therefore be made to nearest available even-numbered size. In the example above, it would be possible to arbitrarily decide upon 0.0006 in. as a running fit rather than the 0.0008 in. ¡1 desired. Final decision would rest largely upon intended use of motorcycle. For highspeed work, the more free fit would be better, while the closer tolerance is suited to road use al average speeds. This consideration may be made in fitting all tolerances.

All fitting must be done with bearings that are clean and dry. Oiled surfaces will take up some clearance and give a false reading.


If flywheel end play is within tolerance and if Timken tapered roller bearings and races pass visual check and have no apparent wear, the same set may be reinstalled. Make certain all parts of bearing are installed in exactly the same order they were removed. If any part of bearing assembly is worn, entire assembly should be replaced.


Install flywheel side outer race snap ring (12) in case. When properly installed, oil hole in snap ring groove will be centered in snap ring gap. Use arbor press and Outer Race Press Plug, Part No. 97194-57 to press outer race parts into crankcase bushing one at a time. Press the races into the case, one from each side, with the widest ends outward to match taper of bearings. Be sure each race bottoms on the snap ring.

The fitting of pinion shaft bearing is done in much the same way as fitting lower rod bearings (see "Fitting Rod Bearings"). A plug fit is first determined using the pinion shaft that will be used on engine being overhauled, or spare shaft of exactly same size. When a plug fit has been found, pinion shaft will enter bearing slowly under its own weight, will turn with only a very light drag and will have no perceptible shake.

A running fit is determined from a plug fit by subtracting

Position flywheel assembly, sprocket shaft up, in vise with copper jaws. Press bearing (15) on sprocket shaft using Bearing Installing Tool, Part No. 97225-55. Sprocket shaft spacer 24036-66 may be needed with bearing installing tool as shown in figure 3-44. Press the parts on using sprocket shaft spacer as a pressing tool only. Turn tool screw onto sprocket shaft thread and tighten securely. Remove tool and slip the bearing, small end up, over sprocket shaft, starting it squarely. Install the small bearing spacer (10) and tool sleeve and press bearing against flange on flywheel

Figure 3-44. Pressing Bearing on Sprocket Shaft

using the tool as shown in figure 3-44. Slip crankcase half, with outer race parts installed, over shaft. Slip bearing over tool screw, small end down toward bearing inner spacer. Position tool sleeve and turn on driver. Turn driver down against sleeve pressing bearings tightly together as shown in figure 3-45. Bearings must be tight against the bearing spacer to provide correct bearing clearance.

Figure 3-45. Pressing Flywheel into Crankcase

Before loosening tool, check to see that the bearing is not preloaded by shaking crankcase half and feeling for a slight amount of play of crankcase half on bearing. Note that if there is no noticeable shake, or if flywheel assembly does not rotate freely in bearing, disassemble bearing and add a 0.003 shim, Part No. 23741-55, on one side of inner race spacer (10, figure 3-31). Again install bearing with tool and recheck for slight play in bearing.

Remove assembly from vise and install bearing washer (5), bearings (4) and bearing washer (3) on pinion shaft. Install new spiral lock ring (2) on groove in pinion shaft. Slip right case half over bearing and against left case half after applying a coat of non-hardening gasket sealer to parting surfaces.

See figure 3-30. Align case halves and tap crankcase studs (5) into holes. These two studs properly align the case halves and must be installed before remaining studs. Start nuts and tighten until snug. Assemble remaining studs, bolts and nuts. Tighten nuts on studs to 12 to 15 ft-lbs torque. Tighten nuts on bolts to 22 to 26 ft-lbs torque.

Check exact amount of flywheel end play with a dial indicator as directed at the beginning of this Section to determine if within specified limits. See figure 3-46.

Install spacer (6, Figure 3-31) in seal (7). Press seal (7) into crankcase with lip toward outside (See Figure 3-31).

Install compensating sprocket shaft extension, see Section 3, "General."


Compensating sprocket must be aligned with rear sprocket through use of correct thickness sprocket spacers. Method for checking and determining correct spacer thickness is given in Section 2, "Drive."

How Remove Flywheel Yamaha Virago
Figure 3-46. Checking Flywheel End Play
+1 0


  • Benjamin
    How to make sure kawasaki z1000 crank pin bushing is working fine or not?
    2 years ago

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