Ignition System - Stihl BR 500 Service Manual

4.2

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 injuries!
Condition
Engine runs roughly, misfires,
temporary low of power
Engine does not run
BR 500, BR 550, BR 600
Cause
Spark plug boot is loose
Spark covered in soot, smeared
with oil
Wrong air gap between ignition coil
and flywheel
Flywheel cracked or damaged or
pole shoes have turned blue
Ignition timing out of adjustment,
flywheel warped, key in flywheel
sheared
Flywheel magnetization weak –
pole shoes have turned blue
No spark
No spark
Remedy
Press boot firmly onto spark plug,
and fit a new leg spring if necessary
Install new spark plug
Reset air gap
Install new flywheel
Install new flywheel
Install new flywheel
Check operation of setting lever
and ignition module
Faulty insulation on ignition lead or
short circuit wire. Use ohmmeter to
check ignition lead for break. If
break is detected or resistance is
high, fit new ignition lead
Replace or clean spark plug,
replace damaged parts of ignition
system
7