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,
SERVICE INFORMATION
GENERAL
CYLINDER/PISTON
•
This section covers
mai
ntenance of the cylinder and
piston.
T
hese procedures can be
d
one with the engine installed in
the
frame.
•
Before
disassembly,
clean the engine thoroughly to prevent dirt from entering it.
•
Be careful not to damage the mating surfaces when removing the
cyl inder. For
example, do
not
use a
screwd
river to pry
the cylinder.
•
Clean all disassembled parts with clean solvent before inspection, use compressed air to dry the parts.
•
Under racing condi
tions,
the piston and piston rings should be replaced after 15
hou
rs of o peration. Replace the piston
pin after
15
hours of operation
.
SPECIFICATIONS
Piston
,
piston
ring
clearance
to-ring
groove
clearance
i
i
end gap
TOp
TROUBLESHOOTING
0.065
- O.
lOa (0.0026
-
0.0039)
0.115 (O.0045)
"
•
Engine top-end problems usually affect engine performance. These problems can be d iagnosed by a compression
t
est
or by tracing engine noise to the top-end with a
sou
nding rod stethoscope.
•
If the performance is
poor
at low
speeds,
check for white smoke
i
n
t
he crankcase breather hose.
If
the hose is smoky,
check fo
r
a seized piston ring.
Compression too
low,
hard starting or poor performance at low speeds
•
Leaking cylinder head gasket
•
Worn, stuck or broken piston rings
•
Worn or damaged cylinder and piston
•
Loose spark plug
Compression too
high,
over-heating or knocking
•
Excessive carbon build-up in cylinder head or on top of piston
Abnormal
noise
•
Worn cylinder and piston
•
Worn piston pin or piston pin hole
•
Worn connecting rod small end
Excessive
smoke
•
Worn cylinder, piston and piston rings
•
Improper installation of piston
r
ings
•
Scored or scratched piston or cylinder wall
9-3
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Table of Contents
Troubleshooting
