Valve / Valve Guide - BRP Johnson 4HP Service Manual

POWERHEAD

VALVE / VALVE GUIDE

Water jacket
Inspect the water jackets for clog or obstruction. Clean the
water jackets if necessary.
VALVE / VALVE GUIDE
Using the micrometer and a bore gauge, take the diameter
readings on the valve stems and the guides in order to check
the guide to stem clearance. Be sure to take readings at
more than one place along length of each stem and guide.
 Micrometer
Valve stem outside diameter
Measure the valve stem outside diameter using the microme-
ter.
Valve stem outside diameter:
Standard:
IN 5.460 – 5.475 mm (0.2150 – 0.2156 in)
EX 5.440 – 5.455 mm (0.2142 – 0.2148 in)
Valve guide inside diameter
Measure the valve guide inside diameter using a small bore
gauge.
Valve guide inside diameter:
Standard:
IN, EX 5.500 – 5.512 mm (0.2165 – 0.2170 in)
Valve guide to valve stem clearance
Standard:
IN 0.025 – 0.052 mm (0.0010 – 0.0020 in)
EX 0.045 – 0.072 mm (0.0018 – 0.0028 in)
Service limit: IN 0.075 mm (0.0030 in)
EX 0.090 mm (0.0035 in)
If the measurement exceeds the service limit, replace the
valve and/or the valve guide.
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