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POWERHEAD
POWERHEAD INSPECTION
The dimensional difference between the two
areas is cylinder taper.
• The cylinder taper must not exceed 0.002 in.
(0.05 mm).
The difference between the measurements and
standard bore is cylinder oversize. For dimen-
sions, refer to SERVICE SPECIFICATIONS AB
MODELS on p. 12.
• The cylinder must not be oversized by more
than 0.003 in. (0.08 mm).
Pistons
Visually inspect pistons for signs of abnormal
wear, scuffing, cracks, or burning.
Piston Rings
For new ring sets, place each ring separately in its
respective bore. Use a piston to square the ring in
the cylinder. Use a feeler gauge to measure the
ring end gap.
Ring end gap should be:
• 0.011 to 0.023 in. (0.28 to 0.58 mm)
IMPORTANT: Ring end gap increases approxi-
mately 0.003 in. (0.076 mm) for each 0.001 in.
(0.025 mm) increase in cylinder bore diameter.
DO NOT exceed cylinder oversize dimension.
Use a machinist’s straightedge to check for proper
ring clearance. Position piston rings on piston.
Push rings into groove and hold straightedge
against the side of the piston. Rings must be even
or just below the surface of piston. Rings must
move freely in piston ring groove.
Bearings
Inspect center main bearings and split sleeves for
excess wear, nicks, or scratches. Replace if nec-
essary.
Inspect crankshaft rod bearings for excess wear,
nicks, or scratches. Replace if necessary.
1. Measurement areas DR3482
002143
31796
24381
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