TOHATSU 40 Service Manual page 106

SECTION 4
6. Check for smooth operation of all crankshaft and connecting
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rod bearings. Inspect the oil pump drive gear for damage.
Upper and lower main bearings, small end connecting rod
bearings, and the oil pump drive gear are serviceable. Wear of other
parts requires replacement of the crankshaft assembly. If lower
main bearing (2) or oil pump drive gear (3) is defective, proceed to
remove the components as follows:
• Remove snap ring (4).
• Install a universal bearing puller with bearing retainer plate and
remove lower main bearing (2) and oil pump drive gear (3) from
the crankshaft.
• See powerhead Assembly procedure for installation.
7. Measure and record the diameter of each cylinder
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bore and the outside diameter of its respective piston.
Subtract the values to calculate the piston clearances. If any bore
diameter or piston clearance exceeds the specified limit, the
cylinder must be professionally bored oversize for use with an
oversize piston.
Standard Bore Diameter
Model
40 / 50
60 / 70
80 / 90
115 / 120 / 140
8. Complete the following inspection for new or used piston
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ring sets. Inspect each ring separately:
• Place ring in its respective cylinder bore.
• Use a piston to square the ring in the bore.
• Use the thickness gauge set (Part No. 353-72251-0) to measure
the ring end gap.
4-32
Piston Clearance
in [mm]
2.677 0.0012 - 0.0028
[68.0] [0.03 - 0.07]
2.913 0.0016 - 0.0031
[74.0] [0.04 - 0.08]
3.386 0.0031 - 0.0051
[86.0] [0.08 - 0.13]
3.465 0.0039 - 0.0055
[88.0] [0.10 - 0.14]
in [mm]
T1232
T1832
T1833
T1235
3-/ 4-Cylinder