Fitting Pinion Shaft Bearing

The fitting of pinion shaft bearing is done in much

Figure 3E-17. Pressing Flywheel into Crankcase

Figure 3E-16. Pressing Bearing on Sprocket Shaft small end up over sprocket shaft, starting it squarely. Install the small bearing spacer and the sprocket shaft spacer. Place tool sleeve on spacers andpress bearing against flange on flywheel using the tool driver and handle as shown in Fig. 3E-16.

Position flywheel assembly in vise with sprocket shaft up. Slip crankcase half (15), with outer race parts installed, over shaft. Slip bearing over tool screw, small end down. Position tool sleeve and turn on driver. Turn driver down against sleeve pressing bearings tightly together as shown in Fig. 3E-17. Bearings must be tight against the bearing spacer to provide correct bearing clearance.

Install bearing lock nut (7) in crankcase using Sprocket Shaft Bearing Nut Wrench, Part No. 97235-55A. Nut should be started by hand. Thread is left hand. Final tightening may be left until case is assembled.

Figure 3E-17. Pressing Flywheel into Crankcase

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

see Fig. 3E-1. Align case halves and tap crankcase stud bolts (6 and 5) into holes. These two studs properly align the case halves and must be installed before remaining studs. Start nuts and tighten until snug. Insert remaining studs and bolt and tighten all nuts securely.

Tighten sprocket shaft bearing nut. Install sprocket spacer (6, Fig. 3E-2) and sprocket or sprocket shaft extension. Start sprocket nut and tighten securely.


PISTON CLEARANCE — New piston fitted in cylinder, .001" to .002" clearance. Piston shapes to cylinder and acquires more clearance after short time in service.

Measure piston at bottom of skirt, front to rear.

Measure cylinder about l/2" from top of bore, front to rear.

PISTON PIN IN PISTON -- Light hand press fit.


PISTON RING GAP AND GROOVE CLEARANCE — With rings Inserted l/2" to 3/4" from top of cylinder — Solid Type Rings .010" to .020" gap - U-Flex Oil Control Rings ll/32" overlap. Rings should be .004" loose in ring grooves of piston.

LOWER CONNECTING ROD BEARING — .001" to .0015" loose.

CONNECTING RODS -- .006" to .010" end play between flywheels -- roller and retainer assembly should be narrower, but not more than .010" narrower than forked rod.

SPROCKET SHAFT TIMKEN BEARING -Sprocket shaft Timken bearings are made up in matched sets. All bearing parts are marked with matching numbers. Do not use bearing parts with different matching numbers. If any part of bearing requires replacing, the entire bearing assembly must be replaced. A complete set of sprocket shaft Timken bearings consists of two inner races with bearings and retainers, one inner bearing race spacer, two outer races, (cones) and one outer race spacer. Inner bearing race spacer determines running clearance between bearings and races.

PINION GEAR SHAFT — .0005" to .001" loose in roller bearing -- .0005" to .0012" loose in cover bushing. Oil slot in cover bushing is centered with drilled feed oil passage in cover.

FLYWHEEL ASSEMELY - Sprocket and gear shafts must run true within .001".

CAM GEAR — .001" to .0015" loose in crankcase and cover bushings -- .001" to .005" end play.

INTERMEDIATE GEARS — .001" to .0015" loose on studs -- .003" to .007" end play.

TAPPET GUIDES -- .0005" to .001" press fit in crankcase.

VALVE TAPPETS — .001" to .002" loose in tappet guides.

ROCKER ARM FIT IN BEARINGS — .001" to .002" loose — .004" to .012" end play.

OIL PUMP DRIVE SHAFT — .0008" to .0012" loose in crankcase bushing.

CRANKCASE BREATHER — .001" to .005" end play — times with front cylinder — opens 1/8" before top center to l/8" after top center, and closes 13/16" to 1-5/16" after bottom center.

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