6-25 POWER UNIT
CYLINDER HEAD
Remove all carbon from combustion chambers.
NOTE:
• Do not use any sharp edged tool to scrape carbon off cylin-
der head or its components.
• Be careful not to scuff or nick metal surfaces when decarboning.
Check cylinder head for cracks in intake and exhaust ports,
combustion chambers, and head surface.
Valve seat
Check valve seat, if cracks or other damage is found, replace
cylinder head.
Cylinder head distortion
Using a straightedge and thickness gauge, measure cylinder
head distortion (gasket surface) at a total of six (6) locations as
shown.
09900-20803 : Thickness gauge
Cylinder head distortion
Service limit : 0.05 mm (0.002 in.)
If measurement exceeds service limit, resurface or replace cyl-
inder head.
NOTE:
Cylinder head can be resurfaced, using a surface plate and
#400 grit wet sandpaper.
Move the cylinder head in a figure eight pattern when sanding.
INSPECTION / SERVICING
NOTE:
If cracks, excessive wear or other damage is found on any com-
ponent, replace component.
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