ZHEJIANG KAYO MOTOR CO., LTD.
www.kayomoto.us
59
For the troubleshooting of cylinder head ,please refer to the following table
Description
Damage Form
Problem
Cause
Correction
Cylinder
head
Too much oil dirt or sand
on the cooling fins.
Poor heat
radiation of the
fins on cylinder
head.
The engine overheats.
Remove the oil dirt or
sand
Carbon
deposit
in the
combustion chamber
Overheating head
The engine overheats
Remove
the
carbon
deposit
Failure of sparking plug
threaded hole
Air leakage between
the sparking plug and
cylinder head
The engine starts hard or
fails to start
Repair the threaded hole
or replace the cylinder
head
Serious
deformation
of cylinder head end
surface
Air leakage between
the cylinder head and
cylinder
The engine starts hard or fails to
start.
Insufficient
engine
output ;Engine speed changes
during idle run
Grind the cylinder head
end surface or replace
the cylinder head
There are pits, ablation or
pock marks, damages on
the working surface of
valve seat.
Air leakage between
the valve and valve
seat due to improper
tightness
The engine starts hard or fails to
start. Insufficient engine output;
engine speed changes during
idle run
Repair the valve seat
The inner hole of valve
guide is over worn
The fitting clearance
between the valve and
the valve is too large
Thick blue and white fume form
the exhaust muffler pipe
Replace the valve guide
The cylinder gasket is
broken
Air leakage between
the cylinder head and
cylinder
The engine starts hard or fails to
start. Insufficient engine output;
Engine speed changes during
idle run
Replace the cylinder
head gasket
The fixing nut is not
properly tightened
Air leakage between
the cylinder head and
cylinder
The engine starts hard or fails to
start. Insufficient engine output;
Engine speed changes during
idle run
Tighten the fixing nut
Spark plug
Improper clearance
between electrodes
Weak or no sparking
from the spark plug
electrodes
Oil leakage between the cylinder
and crankcase
Adjust electrode gap to
0.6~0.7mm
The spark plug electrodes
are jointed by carbon
deposit
No sparking from the
spark plug electrodes
The engine starts hard or fails to
star
Remove
the
carbon
deposit
between
the
electrodes
Excessive carbon deposit
or oil dirt in the spark plug
Weak or no sparking
from the spark plug
electrodes
The engine starts hard or fails to
start. Insufficient engine output;
Engine speed changes during
idle run
Remove
the
carbon
deposit or oil dirt
The spark plug insulator is
damaged
Weak or no sparking
from the spark plug
electrodes
The engine starts hard or fails to
start. Insufficient engine output;
Engine speed changes during
idle run
Replace with a new
spark plug of the same
type
The spark plug is
not properly tightened
Air leakage between
the spark plug and
cylinder head
The engine starts hard or fails to
start. Engine speed changes
during idle run
Tighten the spark plug