16. Honda CB 750 K7 - IGNITION - ELECTRIC STARTER

16. IGNITION SYSTEM ~ HONDA

~ CB750

(2) IGNITION SWITCH

(5) SPARK PLUG

(3) ENGINE STOP SWITCH (B) FUSE

~~
I-(4) CONDENSER
(2) IGNITION COILS --------

(6) BATIERY
(5) CONTACT BREAKER

16-0

~ HONDA IGNITION SYSTEM

~ CB750

TROUBLESHOOTING 16-2
SERVICE INFORMATION 16-2
IGNITION COIL 16-3
CONDENSER 16-4
SPARK ADVANCER 16-5

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16-1

IGNITION SYSTEM ~HONDA

~ CB750

TROUBLESHOOTING Engine Starts but Runs Poorly:
1. Ignition primary circuit
Engine Cranks but Will Not Start:
1. Engine stop switch OFF -Points dirty or fouled
2. No spark at plugs -Incorrect point gap
3. Improper ignition timing -Weak or defective coil
-Defective capacitor
NO Spane at Plugs
1. Engine stop switch OFF -loose or bare wire
2. Points not opening
3. Points burned, wet, fouled or dirty - Intermittent short-circuit in switch
4. No primary current to points and coils 2 Ignition secondary circuit

-Loose or broken wire -Plugs fouled or worn
-Low battey, low charging voltage -Defective or crossed plug wires
-Defective engine stop switch 3. Ignition timing
5. Plugs fouled -Improper ignition timing
6. Defective plug wires -Defective advancer mechanism
7. Coils weak or inoperative
8. Defective condenser

SERVICE INFORMATION

WORKING PRACTICE

Connect each wire properly.
Ensure that the contact breaker points are clean and in good condition.
Keep sparks away from gasoline.

SPECIFICATIONS plug gap D8ES·l (NGK)or X24ES·U (ND)
Spark gap DR8ES·l (NGK) or X24ESR-U (ND) (Canadian model)
Spark plug Point gap 0.6-0. 7 mm (0.0236-0.0276 In)
Capacity 8 mm min. (0.3150 in)
Ignition coil Initial 0.3-0.4 mm (0.0118-0.0158 lin)
Contact breaker points Full advance 0.22-0.26 /I F
Condenser
Ignition timing (F mark) 10° BTDC c" 1,000 ±100 rpm (idle speed)
25° c" 2,500 rpm

16-2

~ HONDA. IGNITION SYSTEM

~ CB750

IGNITION COIL II

SPARK GAP TEST (1) PRIMARY
ELECTRO~
Check the coil output on an electrical
tester. The coils are satisfactory If sparks 8mm
Jump across the gap specified. (0.3150 in .) (2) SPARK

GAP: 8 mm (0.3150 In.)

COIL CONTINUITY TEST

Remove the spark plug caps by turning
them counterclockwise.

Check the primary coil for continuity.

Continuity: Good
No continuity: Replace

Check the secondary coil for continuity.

Continuity: Good
No continuity: Replace

16-3

IGNITION SYSTEM ~HONDA

~ CB750

CONDENSER

CONDENSER CAPACITY

NOTE
e capacitor must be disc arg

before testing the capacity.

Measure the condenser capacity. If it is out ICZ?I
of the specified limits, replace the
condenser. F
CAPACITY: 0.22-0.28,µF

CONDENSER INSTALLATION

INOTE

Do not reverse condenser polarity.

16-4

W\HON'DA IGNITION SYSTEM

~ CB750

SPARK ADVANCER (1) POi NT CAM

SPARK ADVANCER INSPECTION

Check the point advancer cam for freedom
of motion. If the spring fails to return the
cam to the static position, lubricate the
sliding surfaces, and check the spring for
loss of tension and the advancer pin for
excessive wear.

SPARK ADVANCER REMOVAL
AND INSTALLATION

Unscrew the 6 mm hex nut and remove the
special washer.
Remove the screws holding the contact
brea.ker assembly , and remove the
assembly.
Remove the spark advancer.

Assemble the spark advancer, aligning the
advancer pin with the crankshaft hole.

16-5

17. ELECTRIC STARTER ~ HONDA

~ CB750

(10) STARTER MAGNETIC SWITCH

(5) FUSE 15A

/ (6) STARTER SWITCH ~ : M

\

(3) FIELD COIL (2) ARMATURE

(4) FIELD MAGNET (9) RELAY COIL
(8) MAIN SWITCH

(12) NEUTRAL LAMP

(7) BATIERY (13) NEUTRAL SWITCH "'='"
(14) CLUTCH SWITCH

17-0

~HONDA ELECTRIC STARTER

~ CB750

TROUBLESHOOTING 17-2
SERVICE INFORMATION 17-2
STARTER MOT.OR 17- 3
STARTER MAGNETIC SWITCH 17-5
STARTER CLUTCH (A.C. GENERATOR ROTOR) 17-5

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-II

17-1

ELECTRIC STARTER ~ HONDA

~ CB750

TROUBLESHOOTING

Starter MotprWill-Not Turn:
- Dead battery
-Defective ignition switch
- Defective starter switch
- Defective neutral switch
- Defective starter magnetic switch
- loose or disconnected wire or cable
- Neutral diode open
- Defective clutch switch

Starter Motor Turns Engine Slowly:
- low battery
- Excessive resistance in circuit
- Binding in starter motor.

Starter Motor Turns, But Engine Does Not Turn:
- Defective starter clutch
- Defective starter motor gears

Starter Motor and Engine Turn, But Engine Does Not Start:
- Defective ignition system
- Engine problems

SERVICE INFORMATION

WORKJNG PRACTICE

The starter motor can be removed with the engine in the frame.

SPECIFICATIONS

Item Standard Service limit
12-13 mm (0.4724-0.5118 in.) 400gr
Starter motor Brush spring tension
Brush length 7 mm (0.2756 in.)

SPECIAL TOOL 07933-3000000
10.0-12.0 kg-m (72.320-86.784 ft-lbs)
ROTOR PULLER

TORQUE VALUE

A.C. GENERATOR ROTOR FIXING BOLT

17-2

~HONDA ELECTRIC STARTER

~ CB750

STARTER MOTOR

STARTER MOTOR REMOVAL

Disconnect the starter motor cables at the
magnetic switch.

Remove the starter motor cover and remove the
starter motor.

NOTE
It is necessary to remove the carburetor
first, if the engine is mounted in the frame.

BRUSH INSPECTION

Remove the starter motor case screws and the
brush cover.

NOTE
Look for spacers on the armature shaft
ends. Replace them in proper position .

Inspect the brushes; measure brush length.
Measure brush spring tension.
SERVICE LIMIT:

Brush lingth: 7 mm (0.2756 in.)
Brush tension: 400 gr

COMMUTATOR INSPECTION

Measure the diameter of the commutator and
height of the segments above the insulator.
SERVICE LIMITS:

DIAMETER: 27 mm (1.0630 in.)
HEIGHT: 0.2 mm 10.0079 in.)

NOTE
Do not use emery or sand paper on the
commutator.

17-3

ELECTRIC STARTER ~HONDA

ARMATURE COIL INSPECTION ~ CB750

Check for continuity between pairs of com- 1<7>1
mutator bars, and also between commutator
bars and armature shaft. Q

Replace the starter motor if the armature coils
are open, or shorted to the amature shaft.

FIELD COIL INSPECTION

Check for continuity from the cable terminal to
the motor case and from the cable ,erminal to
the brush wire.

Replace the starter motor if the field coil is not
continuous or if it is shorted to the motor case.

STARTER MOTOR ASSEMBLY

• The positive primary cord is insulated.
• Align the mark on the case.

17-4

~HONDA ELECTRIC STARTER

~ CB750

STARTER

MAGNETIC SWITCH
INSPECTION

Before removing magnetic switch,
disconnect the negative battery cable from
the battery.

Test the primary windings for continuity. Also
test for shorts from either primary lead to the
case.

Replace the magnetic switch if the primary coil
has an open circuit, shorted, or is shorted to the
case.

Connect 12-volt source across primary leads.
Magnetic switch should make an audible click.

Test for continuity across the large terminals
when the magentic switch is energized.

If there is any resistance, the relay must be
replaced

STARTER CLUTCH
(A.C. GENERATOR
ROTOR) INSPECTION

Remove the generator cover.

Remove the A.C . generator rotor and starting
clutch gear.

Check to make sure that the clutch roller
operates smoothly .

STARTER REDUCTION GEAR
INSPECTION

Remove the generator cover.

Check gears for wear or damage.

17-5