Section 2: Ignition - Generac Power Systems OHVI GSH 220 Service Manual

GeNerAl
The ignition system typically used on single cylinder engines
is a solid-state (breakerless) type. The system utilizes a magnet
on the engine flywheel to induce a relatively low voltage into
an ignition coil assembly. Ignition coil internal components
increase the voltage and deliver the resulting high voltage
across the spark plug gap.
The ignition coil houses a solid-state circuit board that con-
trols ignition timing. Timing is fixed, nonadjustable and spark
advance is automatic.
MAjor CoMPoNeNTS
Major components of the ignition system include (a) the igni-
tion coil assembly, (b) the spark plug, (c) the engine run switch
and (d) the engine flywheel (see Figures 2- and 2-).
ENGINE
SPARK
RUN SWITCH
PLUG
Figure 2-1. Ignition System Components
IGNITIoN CoIl ASSeMblY
Solid-state components encapsulated in the ignition coil are
not accessible and cannot be serviced. If the coil is defective,
the entire assembly must be replaced. The air gap between the
coil and the flywheel magnet is fixed and nonadjustable.
The ignition coil assembly (Figure 2.2) consists of (a) ignition
coil, (b) spark plug high tension lead and (c) spark plug boot.
Figure 2-2. Ignition Coil Assembly
The spark plug should be cleaned and regapped periodically.
The plug should be replaced every 00 hours of operation or
once annually, whichever comes first.
Set spark plug gap to 0.00 inch (0.76mm) (Figure 2-).
Note: For proper spark plug replacement, refer to the
owner's manual for the specific product. Always use
original GENERAC® replacement parts.
IGNITION
COIL
CHECKING FLYWHEEL MAGNET:
ASSEMBLY
The flywheel magnet rarely loses its magnetism. If you
suspect a magnet might be defective, a rough test can be
performed as follows:
. Place the flywheel on a wooden surface.
2. Hold a screwdriver at the extreme end of its handle and
with its point down.
. Move the tip of the screwdriver to about / inch (9mm)
from the magnet. The screwdriver blade should be pulled
in against the magnet.
FLYWHEEL KEY:
The flywheel's taper is locked on the crankshaft taper by the
torque of the flywheel nut. A keyway is provided for alignment
only and theoretically carries no load.
If the flywheel key becomes sheared or even partially sheared,
ignition timing can change. Incorrect timing can result in hard
starting or failure to start.
FLYWHEEL REMOVAL:
Use a strap wrench to prevent the flywheel from turning.
Remove the FLYWHEEL NUT. Then, remove the CONICAL
WASHER and the STARTER CUP.
Use a commercially available flywheel puller to remove the
flywheel from the engine tapered shaft.
2-

SeCTIoN 2: IGNITIoN

SPArk PluG
SET PLUG GAP AT 0.030 inch
(0.76 mm)
Figure 2-3. Setting Spark Plug Gap
FlYwHeel
2