17
Engine Cylinder Head Inspection and Replacement Procedure
16. Install the rocker cover (Figure 26)
Tighten the rocker cover cap nut.
The seal washer under the cap nut must be installed.
Cap nut (width across
À
at) 22 [mm]
Tightening torque
13.7 ~ 15.7[N·m]
17. Spark plug installation (Figure 27)
(1) If the tip of the plug is completely black with dry carbon,
the mixture may be too rich, the ignition timing may be
retarded, or oil may be going up and down within the
cylinder. Investigate these possibilities.
(2) If the tip of the plug is black and moist, the air cleaner
element may be clogged. Investigate this possibility.
(3) If the insulator at the tip of the plug is burned completely
white, and a portion of it is melted together with the
electrode, the ignition timing may be too advanced, there
may be a problem with the cooling system, the plug may
not be suf
¿
ciently tightened to the engine, or the mixture
may be too lean. Investigate these possibilities.
(4) Check for damage to the washer and cracking on the
insulator.
(5) If the tip of the centre electrode is rounded as shown in
c
of Figure 28, replace the plug with a new one.
(6) If the ground electrode is worn as shown in
d
of Figure
28, replace the plug with a new one.
(7) Check the electrode gap of the sparkplug
Reference value
0.4 ~ 0.5 [mm]
Caution
c
Do not adjust the gap, because an iridium chip is used.
d
Do not insert a thickness gauge between the electrodes or
clean them with a wire brush.
(8) Check that there is no looseness in the terminal part.
(9) Check for cracking, damage, or marks of electrical leaks
on the insulator.
Resistance
5.25±2.25 [k
ȍ
]
(10) Use a plug wrench to insert the plug in the installation
hole, and rotate it by hand a couple of times. (Figure 29)
(11) Use a deep socket wrench to tighten the plug to the
speci
¿
ed torque.
Socket (width across
À
at)
16 [mm]
Tightening torque
19.6 ~ 29.4[N·m]
Figure
.26
Figure
.26
Terminal
Insulator
Electrode
Gap
Figure
.27
Terminal
Insulator
Electrode
Gap
Figure
.27
Centre electrode rounded
Ground electrode
eaten away
Electrode loss
Figure
.28
Centre electrode rounded
Ground electrode
eaten away
Electrode loss
Figure
.28
Figure
.29
Temporarily tighten spark plug
Plug
Figure
.29
Temporarily tighten spark plug
Plug
GHP̲Main̲Parts̲Replacement.indd 17
2012/07/31 17:54:21
