81
GZ187A
CYLINDER/CYLINDER HEAD
ASSEMBLY
NOTE: If the cylinder/cylinder head cannot be trued,
they must be replaced as an assembly.
Cleaning/Inspecting Cylinder Head
1. Using a non-metallic carbon removal tool, remove any
carbon buildup from the combustion chamber being
careful not to nick, scrape, or damage the combustion
chamber or the sealing surface.
2. Inspect the spark plug hole for any damaged threads.
Repair damaged threads using a “heli-coil” insert.
3. Place the cylinder head on the surface plate covered
with #400 grit wet-or-dry sandpaper. Using light pres-
sure, move the cylinder head in a figure eight motion.
Inspect the sealing surface for any indication of high
spots. A high spot can be noted by a bright metallic
finish. Correct any high spots before assembly by con-
tinuing to move the cylinder head in a figure eight
motion until a uniform bright metallic finish is
attained.
Measuring Cylinder Head Distortion
1. Remove any carbon buildup in the combustion cham-
ber.
2. Lay a straightedge across the cylinder head; then
using a feeler gauge, check the distortion between the
head and the straightedge.
3. Maximum distortion must not exceed specifications.
CC141D
Cleaning/Inspecting Cylinder
1. Wash the cylinder in parts-cleaning solvent.
2. Inspect the cylinder for pitting, scoring, scuffing,
warpage, and corrosion. If marks are found, repair the
surface using a cylinder hone (see Inspecting Cylinder
in this sub-section).
3. Place the cylinder on the surface plate covered with
#400 grit wet-or-dry sandpaper. Using light pressure,
move the cylinder in a figure eight motion. Inspect the
sealing surface for any indication of high spots. A
high spot can be noted by a bright metallic finish. Cor-
rect any high spots before assembly by continuing to
move the cylinder in a figure eight motion until a uni-
form bright metallic finish is attained.
CC129D
Inspecting Cam Chain Guide
1. Inspect cam chain guide for cuts, tears, breaks, or
chips.
2. If the chain guide is damaged, it must be replaced.
Inspecting Cylinder
1. Using a slide gauge and a dial indicator or a snap
gauge, measure the cylinder bore diameter in three
locations from top to bottom and again from top to
bottom at 90° from the first measurements for a total
of six measurements. The trueness (out-of-roundness)
is the difference between the highest and lowest read-
ing. Maximum trueness (out-of-roundness) must not
exceed specifications.
CAUTION
Incorrect installation of the piston rings will result in
engine damage.
CAUTION
The cylinder head studs must be removed for this pro-
cedure.
CAUTION
Water or parts-cleaning solvent must be used in con-
junction with the wet-or-dry sandpaper or damage to
the sealing surface may result.
CAUTION
Water or parts-cleaning solvent must be used in con-
junction with the wet-or-dry sandpaper or damage to
the sealing surface may result.