12 MS 461, MS 461-R
3.5 Ignition System
Exercise extreme caution while
carrying out maintenance and
repair work on the ignition system.
The high voltages which occur can
cause serious or fatal accidents.
Condition Cause Remedy
Engine runs roughly, misfires,
temporary loss of power
Spark plug boot is loose Press boot firmly onto spark plug, fit
new spring/spark plug boot if
necessary
Spark plug sooted, smeared with oil Clean the spark plug or replace if
necessary.
If sooting keeps recurring, check air
filter
Ignition lead loose in ignition
module
Install new ignition lead
Fuel/oil mixture
– too much oil
Use correct mixture of fuel and oil
Incorrect air gap between ignition
module and flywheel
Set air gap correctly
Flywheel cracked or
damaged or pole shoes have
turned blue
Install new flywheel
Ignition timing wrong, flywheel out
of adjustment
– key has sheared off or slot in
flywheel is worn
Install new flywheel or key
Weak magnetization in flywheel Install new flywheel
Irregular spark Check operation of switch shaft/
contact spring and ignition module
Faulty insulation or break in ignition
lead or short circuit wire. Check
ignition lead/ignition module and
replace as necessary.
Check operation of spark plug.
Clean the spark plug or replace if
necessary.
The carburetor or engine may also be the cause of poor engine running behavior
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