Makita PM7651H Technical Information page 22

6-9-4 Checking of Ignition coil (cont.)
Next, check the behavior during engine's run as the following order.
Purpose: Clarify the cause of stall and poor acceleration resulting from; vanishment of sparks or the other reasons.
[1] Attach Alligator clip to Spark
plug.
[3] Start Engine, and check that the sparks are found out continuously during idling, after that, while accelerating the rpm
of engine to the maximum gradually.
Note: Some models' ignitions stop the sparks to protect engine as soon as the rpm reaches the maximum. In case the
sparks cannot be seen once or more in ten times/ the sparks cannot be generated when the rpm is over a certain
level, replace Ignition coil with a new one.
When the behavior of engine is abnormal during check meanwhile the spark is normal, detect the parts except
Ignition coil.
Note: Quick check is required. The long checking could result in melting of the cover of Alligator clip.
Fig. 6-9-4-1
[2] Turn Spark distance adjusting knob so that the spark
distance in Spark window reduces to 4 mm.
(When the distance is narrow, you cannot see the spark.
When the distance is still wide such as 6mm distance,
Ignition coil may break.)
Spark window
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