ENGINE
3-13
ENGINE COMPONENTS INSPECTION
AND SERVICE
CYLINDER HEAD
Remove carbon from the combustion chamber and clean the cyl-
inder head.
Check the gasket surface of the cylinder head for distortion. Use
a straightedge and thickness gauge. Take clearance readings at
several places.
'
09900-20803: Thickness gauge
%
Cylinder head distortion
Service Limit: 0.05 mm (0.002 in)
If clearance readings exceed the service limit, flatten the cylinder
head. Place a sheet of emery paper (about #400 grit) on a sur-
face plate. Use a figure-eight motion when grinding the cylinder
head surface.
The gasket surface must be smooth and perfectly flat, for a tight
fit. A leaky joint can be the cause of reduced power and increased
fuel consumption.
CYLINDER
Remove carbon from the exhaust port and the upper part of the
cylinder. Take care not to damage the surface of the cylinder wall.
Measure the cylinder bore with the cylinder gauge at 20 mm (0.8
in) from the top of the cylinder.
Rebore the cylinder when the cylinder bore exceeds the service
limit. Oversize pistons are available in two sizes: 0.5 mm and 1.0
mm
'
09900-20508: Cylinder gauge set
%
Cylinder bore
Service Limit: 41.065 mm (1.6167 in)
Chamfer the port edges after reboring. Use a scraper and take
care not to nick the surface of the walls. Use emery paper to
smooth the chamfered edges.
NOTE:
Shallow grooves or minor scuffs can be removed by using emery
paper (about #400). If the flaws are deep grooves or cannot be
removed with the emery paper, the cylinder must be replaced
with a new one.
20 mm
(0.8 in)
0.5 – 1.0 mm
0.3 – 0.8 mm
0.5 – 1.0 mm
