Spark Plug
If engine is down on power, difficult to start or runs poorly at idling speed, first check the spark plug.
Fit a new spark plug after approx. 100 operating hours or earlier if the electrodes are badly eroded.
Wrong fuel mix (too much engine oil in the gasoline), a dirty air filter and unfavorable running conditions (mostly at part throttle etc.) affect the condition of the spark plug. These factors cause deposits to form on the insulator nose which may result in trouble in operation.
Remove the spark plug
NMove the Master Control lever to the stop position 0
137BA008 KN
NTurn the knob above the rear handle in the direction of the arrow and remove the carburetor box cover
1
2
137BA009 KN
NLift the air baffle (1) up and off N Unplug spark plug boot (2)
N Unscrew spark plug
Checking the Spark Plug
| KN |
A | 000BA039 |
|
NClean dirty spark plug.
NCheck electrode gap (A) and readjust if necessary – see "Specifications."
NUse only resistor type spark plugs of the approved range.
Rectify problems that have caused fouling of spark plug:
–too much oil in fuel mix,
–dirty air filter,
–unfavorable running conditions, e.g. operating at part load.
English
1
2
000BA071 KN
WARNING
To reduce the risk of fire and burn injury, use only spark plugs authorized by STIHL. Always press spark plug boot (1) snugly onto spark plug terminal (2) of the proper size. (Note: If terminal has detachable SAE adapter nut, it must be securely attached.) A loose connection between spark plug boot and ignition wire connector in the boot may create arcing that could ignite combustible fumes and cause a fire.
Install spark plug
NScrew in the spark plug and press on the spark plug boot
NInstall air baffle
NMount carburetor box cover
MS 660 | 43 |
