Carbon deposits (from the combustion
Use a rounded scraper.
Do not use a sharp instrument to avoid dam-
aging or scratching:
Spark plug threads
Scratches/damage → Replace.
Cylinder head warpage
Out of specification → Resurface.
Cylinder head warpage:
Less than 0.05 mm (0.002 in)
Warpage measurement and resurface-
Place a straightedge and a feeler gauge
across the cylinder head.
Use a feeler gauge to measure the
If the warpage is out of specification,
resurface the cylinder head.
Place a 400 ~ 600 grit wet sandpaper on
the surface plate, and resurface the head
using a figure-eight sanding pattern.
To ensure an even surface rotate the cylin-
der head several times.
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