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This section describes repair, focusing on portions requiring frequent repair. See the TROUBLESHOOTING
GUIDE in the previous section as the context for the following descriptions.
1. Precautions on maintenance, inspection and repair
•
The fuel used readily ignites; therefore, never bring the product near a flame.
•
Use new gaskets at reassembly.
• Prior to disassembly for repair, remove the fuel into separate containers, and allow the tool to cool down.
• During repair, startup or running, use adequate care for portions posing the risk of burn injury or electric
shock, such as hot areas including the muffler, high voltage cord, and spark plug.
• Before running the tool with the cut-off wheel attached, make sure that there are no other people nearby.
• Ensure proper ventilation when performing repair in a small room or other poorly ventilated space.
2. Inspection criteria for each section and consumable parts
Model
Item
CM 75EAP
CM 75EBP
Idling revolutions
2,500 ± 200 min
-1
No-load maximum revolutions
(with cut-off wheel)
9,800 ± 400 min
-1
Clutch engagement
3,800 ± 300 min
-1
Spindle revolutions
4,050 ± 150 min
-1
Accelerating performance
Smooth acceleration
Gap between magneto rotor
and ignition coil ass’y
0.2 to 0.4 mm
Spark plug
NGK BPMR7A
Gap between spark plug
electrodes
0.6 to 0.7 mm
Diamond cutter dimensions
305 mm in outside dia.
20 mm in hole dia.
355 mm in outside dia.
20 mm in hole dia.
(A diamond cutter of 25.4 mm in hole dia. is available
when using the accessory adapter collar.)
Cut-off wheel dimensions
305 mm in outside dia.
20 mm in hole dia.
3.5 mm in thickness
355 mm in outside dia.
20 mm in hole dia.
4.0 mm in thickness
(A cut-off wheel of 25.4 mm in hole dia. is available
when using the accessory adapter collar)
Max. circumferential speed of
cut-off wheel
80 m/s
100 m/s
* This engine cutter controls the maximum speed to 9,800 ± 400 min
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in order to prevent the cut-off wheel
from breaking. Therefore, the pulse-count type of tachometer used for detecting ignition plug firing pulses
cannot measure maximum speed. Use one of the following methods to measure maximum speed:
• Use a tachometer of the electromagnetic induction type for detecting the movement of magnetic steel in
the magneto rotor.
• Use a stroboscope or similar instrument to measure the cut-off wheel rotation (spindle speed). Make a
safety check before running the cut-off wheel, and be very careful to avoid injury.
REPAIR GUIDE