Makita PM7651H Technical Information page 20

6-9 Ignition system
6-9-1 Checking plug cap
[1] Remove Plug cap from Spark plug, then check the continuity between Plug cap spring and the ground (earth) terminal of
Ignition coil with 1R402-A. (Fig. 6-9-1-1)
[2] If there is no or intermittent continuity, check the continuity between Ignition cable and Plug cap spring by following the steps
described below.
(1) Apply spray lubricant in Plug cap, pull out Plug cap by turning it. (Fig. 6-9-1-2)
(2) Check if Plug cap spring is properly connected to Ignition cable. If not, connect them properly.
Also check Plug cap for any crack. If Plug cap is cracked, replace it with a new one.
(3) Insert Plug cap spring in the center of Ignition cable. Then using small pliers, put them back into Plug cap carefully not
to disconnect Plug cap spring from Ignition cable.
(4) Make sure that Plug cap spring is firmly connected to Ignition cable by doing the same as you did in step (1).
Fig. 6-9-1-1
Ground (earth)
terminal or
metal part of
the machine
6-9-2 Checking Spark plug
WARNING!!
When a spark is produced, high-voltage current is delivered from Ignition coil to Spark plug. Therefore, it is 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
from the electrodes and the ceramic insulator around the
center electrode.
[3] Adjust the electrode gap to 0.6 to 0.7mm by inserting
0.7mm Feeler gauge set of 1R366 into the gap and
carefully bending the side electrode.
Plug cap
Spark plug
Plug cap spring
(located in Plug
cap)
Ignition cable
Ignition coil
High voltage
cable
Side electrode
20 / 41
Fig. 6-9-1-2
Spray lubricant
Plug cap
Plug cap
spring
Fig. 6-9-2-1
Electrode gap
must be 0.6 to
0.7mm.
Center electrode