Main Bearing Selection

Notice: Do not shim, scrape, or file bearing inserts. Do not touch the bearing surface of the insert with bare fingers. Skin oil and acids will etch the bearing surface.

1. The crankshaft bearings are of the precision insert type. The crankshaft bearings are available in standard and 0.25 mm (0.0098 inch) undersize. Undersize refers to crankshaft diameter. Both standard and undersize bearings are each available in 5 sizes (tolerances) differing in thickness in the center of the bearing. The upper bearing half has an oil groove, the lower bearing half does not have an oil groove.

Important: If crankshaft bearing failure is due to other than normal wear, investigate the cause. Inspect the crankshaft bearing bores.





2. Inspect the crankshaft main bearing bores using the following procedure:
2.1. Tighten the lower crankcase cap to specification.
2.2. Measure the bearing bore for taper and out-of-round.
2.3. No taper or out-of-round should exist.

3. Install the original crankshaft main bearing inserts on to the cylinder block and the lower crankcase assembly.
4. Carefully place the crankshaft on to the bearing inserts in the cylinder block.

Important: Do not turn the crankshaft while measuring the bearing clearance.





5. Lay a piece of gauging plastic across each crankshaft main journal (avoiding the oil hole).
6. Carefully place the lower crankcase assembly on to the cylinder block.

Notice: Refer to Fastener Notice in Service Precautions.





7. Install the ten main bearing cap bolts (1-10). Progressively torque the main bearing cap bolts using two steps in the sequence shown.
1st Pass
Tighten the main bearing cap bolts to 42 Nm (31 ft. lbs.).

2nd Pass
Tighten the main bearing cap bolts to 60 Nm (44 ft. lbs.).

8. Install the twelve lower crankcase bolts (11-22). Progressively torque the lower crankcase bolts using two steps in the sequence shown.
1st Pass
Tighten the twelve lower crankcase bolts to 19 Nm (1 4 ft. lbs.)

2nd Pass
Tighten the twelve lower crankcase bolts to 27 Nm (20 ft. lbs.)

9. After reaching the proper torque, remove the lower crankcase bolts and the crankshaft main bearing cap bolts.
10. Carefully remove the lower crankcase assembly from the cylinder block.





11. Measure the gauging plastic at its widest point.
Standard Oil Clearance: 0.026 - 0.046 mm (0.0010 - 0.0018 inch)
Maximum Oil Clearance: 0.060 mm (0.0023 inch)

12. A new standard bearing may produce the correct oil clearance. If not, regrind the crankshaft and install 0.25 mm (0.0098 inch) undersize bearings.





13. Crankweb number 2 is stamped with numbers. The numbers represent the corresponding journal diameter marked with an arrow. If using a standard bearing, replace it with one having the same color. If the color of the bearing cannot be determined, select the correct bearing by interpreting the numbers and letters imprinted on the cylinder block and crankshaft.
^ Number 1 represents a journal diameter of 57.994 - 58.000 mm (2.2832 - 2.2834 inch).
^ Number 2 represents a journal diameter of 57.988 - 57.994 mm (2.2830 - 2.2832 inch).
^ Number 3 represents a journal diameter of 57.982 - 57.988 mm (2.2828 - 2.2829 inch).





14. The lower crankcase is stamped with letters. The letters represent the crankshaft bearing cap bore diameter without the bearings installed.
^ Letter A represents a crankshaft bearing cap bore diameter of 62.000 - 62.006 mm (2.4409 - 2.4411 inch).
^ Letter B represents a crankshaft bearing cap bore diameter of 62.006 - 62.012 mm (2.4412 - 2.4414 inch).
^ Letter C represents a crankshaft bearing cap bore diameter of 62.012 - 62.018 mm (2.4414 - 2.4416 inch).





15. There are 5 kinds of standard bearings available. The bearings differ in thickness at the center of the bearing. Each bearing is marked with paint (1). The color of the paint indicates the thickness of the bearing.
^ Green paint indicates a bearing thickness of 1.993 - 1.997 mm (0.0785 - 0.0786 inch).
^ Black paint indicates a bearing thickness of 1.996 - 2.000 mm (0.0786 - 0.0787 inch).
^ No paint (colorless) indicates a bearing thickness of 1.999 - 2.003 mm (0.0787 - 0.0788 inch).
^ Yellow paint indicates a bearing thickness of 2.002 - 2.006 mm (0.0788 - 0.0789 inch).
^ Blue paint indicates a bearing thickness of 2.005 - 2.009 mm (0.0789 - 0.0790 inch).

16. Refer to the standard main bearing selection table Specifications. Using the intersection of the letters and numbers, select the correct bearing from the table. Measure the oil clearance. If the oil clearance is incorrect install the next thicker bearing and recheck the oil clearance.

Undersize Main Bearing Selection
1. If new standard bearings do not produce the correct oil clearance, regrind the crankshaft to a finished diameter of 57.732-57.750 mm 92.2729-2.2736 inch) and install 0.25 mm (0.0098 inch) undersize bearings. Undersize bearings are available in 5 sizes (tolerances) differing in thickness in the center of the bearing.





2. Undersize bearings are distinguished from standard size bearings by a double paint mark (1).
^ Green and red paint indicates a bearing thickness of 2.118 - 2.122 mm (0.0834 - 0.0835 inch).
^ Black and red paint indicates a bearing thickness of 2.121 - 2.125 mm (0.0835 - 0.0836 inch).
^ Red paint only indicates a bearing thickness of 2.124 - 2.128 mm (0.0836 - 0.0837 inch).
^ Yellow and red paint indicates a bearing thickness of 2.127 - 2.131 mm (0.0837 - 0.0838 inch).
^ Blue and red paint indicates a bearing thickness of 2.130 - 2.134 mm (0.0838 - 0.0839 inch).





3. Measure the reground crankshaft journals for out-of-round.
Maximum Out-of-Round 0.01 mm (0.0004 inch)
4. Measure the reground crankshaft journals for taper.
Maximum Taper 0.01 mm (0.0004 inch)
5. Measure the reground crankshaft journals for size.
6. Refer to the undersize main bearing selection table Specifications. Using the intersection of the measured journal size and the letters on the lower crankcase select the correct sized bearing from the table. Measure the oil clearance. If the oil clearance is incorrect install the next thicker bearing and recheck the oil clearance.