Clean Cylinder Bore After Honing
Proper cleaning of cylinder walls following boring and/
or honing is very critical to a successful overhaul.
Machining grit left in cylinder bore can destroy an engine
in less than 1 hour of operation after a rebuild.
Final cleaning operation should always be a thorough
scrubbing with a brush and hot, soapy water. Use a
strong detergent capable of breaking down machining
oil while maintaining a good level of suds. If suds break
down during cleaning, discard dirty water and start again
with more hot water and detergent. Following scrubbing,
rinse cylinder with very hot, clear water, dry it completely,
and apply a light coating of engine oil to prevent rusting.
Measuring Piston-to-Bore Clearance
Piston Detail
A
A 6 mm (0.24 in.)
NOTE: Do not use a feeler gauge to measure piston-to-
bore clearance – it will yield inaccurate
measurements. Always use a micrometer.
Before installing piston into cylinder bore, it is
necessary clearance be accurately checked. This step
is often overlooked, and if clearances are not within
specifi cations, engine failure will usually result.
Use these following procedures to accurately measure
piston-to-bore clearance:
1. Use a micrometer and measure diameter of piston 6
mm (0.24 in.) above bottom of piston skirt and
perpendicular to piston pin.
2. Use an inside micrometer, telescoping gauge, or
bore gauge and measure cylinder bore. Take
measurement approximately 63.5 mm (2.5 in.) below
top of bore and perpendicular to piston pin.
3. Piston-to-bore clearance is difference between bore
diameter and piston diameter (step 2 minus step 1).
Disassembly/Inspection and Service
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