Test 60 - Check And Adjust Ignition Magnetos - Generac Power Systems 7 kW NG Repair Manual

ENGINE/DC CONTROL
Results
1. If the VOM indicated CONTINUITY to ground in Step 6,
repair or replace shorted ground Wire 18 between the
engine and the J4 connector.
2. If the VOM did NOT indicate CONTINUITY to ground in
Step 6, replace the control board and re-test for spark.
3. If ignition (spark) was not present in Step 2 with Wire 18
disconnected, proceed to Test 60.
TEST 60 – CHECK AND ADJUST IGNITION
MAGNETOS
Discussion
In Test 55, a spark tester was used to check for engine ignition.
If sparking or weak spark occurred, one possible cause might
be the ignition magneto(s). This test consists of checking
ohm values across the primary and secondary windings of
the magneto and adjusting the air gap between the ignition
magneto(s) and the flywheel. The flywheel and flywheel key will
also be checked during this test. A diode is installed before the
primary winding inside the coil. This is done to inhibit a spark
occurring on both magnetos at the same time.
Procedure: Testing Magnetos
1. On V-twin generators, (refer to Figure 140) remove Wire
18 from the stud located above the oil cooler. On single
cylinder generators, (refer to Figure 141) disconnect Wire
18 at the bullet connector.
2. Disconnect spark plug wires from the spark plugs on
cylinder one and two.
3. Set VOM to measure resistance.
4. Connect the positive (red) meter lead to the bolt connector
where Wire 18 was disconnected in Step 1. Connect the
negative (black) meter lead to a clean frame ground. A
resistance of approximately 300K ±10K Ohms should
be measured. This reading is the primary winding of both
coils in parallel.
5. Connect the positive meter lead to the spark plug wire and
connect the negative meter lead to a clean frame ground.
Approximately 14K ±3 Ohms should be measured. This
reading is the secondary winding of both coils in parallel.
If INFINITY, or a low or high ohm reading is measured,
replace the magnetos.
6. Connect the negative (black) meter lead to the bolt
connector where Wire 18 was disconnected in Step 1.
Connect the positive (red) meter lead to the spark plug wire
on cylinder number two. The meter should indicate INFINITY
(open). This step is testing the diodes in both magnetos to
ensure they are still functioning.
7. Repeat Step 6 on cylinder two. If INFINITY (open) is not
measured, replace the magnetos.
PART 4
Note: It is recommended to replace Magnetos in pairs.
Procedure: Adjusting Magneto Flywheel Gap
Note: The air gap between the ignition magneto and the fly-
wheel on single cylinder engines is not adjustable. Proceed
directly to Step 10 for single cylinder engines. For V-twin
engines, proceed as follows.
1. See Figure 142. Rotate the flywheel (by hand) until the
magnet is under the module (armature) laminations.
2. Place a 0.008-0.012 inch (0.20-0.30mm) thickness
gauge between the flywheel magnet and the module
laminations.
Note: A business card is approximately 0.010 inch thick.
3. Loosen the mounting screws and let the magnet pull the
magneto down against the thickness gauge.
4. Tighten both mounting screws.
5. To remove the thickness gauge, rotate the flywheel
(manually).
6. Repeat the above procedure for the second magneto.
0.008-0.012" GAUGE
MAGNETO
Figure 142. Setting Ignition Magneto (Armature) Air Gap
7. Repeat Test 55 and check for spark across the spark
tester gap.
a. A spark test may be conducted with unit dissembled by
following this procedure.
b. Battery must be connected.
c. J4 Connector must be connected to the controller.
d. Remove Wire 56 from the SCR located beneath the
controller.
 Make sure all debris is cleared from the engine
compartment and all body parts are clear from flywheel
before proceeding.
e. Refer to Test 55 to check for spark.
f. Utilizing a jumper wire, connect a wire to the 194
terminal block. Connect the other end to where Wire 56
Section 4.5
Diagnostic Tests
Page 131