BRP Johnson 4HP Service Manual page 103

Crankshaft runout
Measure the crankshaft runout as shown in the figure.

Dial gauge
Magnetic stand
Steel "V" block set
Crankshaft runout:
Service limit: 0.05 mm (0.002 in)
If the measurement exceeds the service limit, replace the
crankshaft.
Crankshaft lower journal oil clearance
To check the clearance, measure the following items:
•
Crankshaft lower holder (crankcase) inside diameter.
•
Crankshaft lower journal outside diameter.

Micrometer
Dial caliper
Crankshaft lower journal oil clearance:
Standard: 0.020 – 0.062 mm (0.0008 – 0.0024 in)
Service limit: 0.100 mm (0.0039 in)
If the clearance exceeds the service limit, replace the crank-
shaft and/or the crankcase.
Crankshaft lower holder inside diameter:
Standard: 25.000 – 25.021 mm (0.9843 – 0.9851 in)
Crankshaft lower journal outside diameter:
Standard: 24.959 – 24.980 mm (0.9826 – 0.9835 in)
PISTON PIN / CONROD / CRANKSHAFT
POWERHEAD
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