Makita PM7650H Technical Information page 15

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[4] DISASSEMBLY/ASSEMBLY
[4]-10. Ignition system (cont.)
CHECKING SPARK PLUG
WARNING !!
• When a spark is produced, high-voltage current is delivered from Ignition coil to Spark plug.
It is, therefore, very dangerous to pull Recoil starter knob with your hand on Ignition cable.
Be sure to keep your hands off from Ignition cable when checking for spark.
• Fuel is extremely flammable and fuel vapors are explosive.
Therefore, clean up spilled fuel before starting to check for spark.
Also, be careful not to do the check near Carburetor.
(1) Remove Plug cap from Spark plug, then Spark plug from Cylinder head complete with the supplied socket wrench.
Note: If the electrodes of Spark plug are wet, wipe them with a rag then dry them with an air blower.
(2) Using a wire brush, carefully clean up carbon deposits (if any) from the electrodes and the ceramic insulator around
the center electrode.
(3) Adjust the electrode gap to 0.6 to 0.7mm by carefully bending
the side electrode.
Use Feeler gauge set (1R366) to check the gap width:
between the center electrode and the side electrode, insert 0.7mm leaf
or a combination of 0.25mm and 0.35mm leaves of the Feeler gauge set.
(Fig. 42)
(4) Install another Spark plug into spark plug hole to prevent air/fuel mixture
from leaking outside of engine.
(5) Connect the removed Spark plug with Plug cap, then ground the threads
of Spark plug to a proper metal part of the engine.
(6) With Stop switch on, pull Recoil starter knob gently and check for spark.
Note: It is hard to see the spark in a bright location.
Therefore, be sure to do the check in a shady but well-ventilated place.
(7) If spark is not produced, replace Spark plug with new one,
then check for spark by following the procedure (1) to (6) once again.
REMOVING IGNITION COIL
Remove Wire (primary wire) from Ignition coil, then remove Ignition coil
from the engine by unscrewing two M4x20 Socket head bolts. (Fig. 43)
Fig. 43
M4x20 Socket head bolt (2 pcs)
Ignition coil
Fig. 42
side electrode
center electrode
P 15/26
Electrode gap
must be
0.6 to 0.7mm.