Charging Circuit - Honda CB350 Repair Manual

ELECTRICAL SYSTEM 113
4. In the event of the above troubles,
or a no—spark condition at one cylinder,
the plug, plug cap, lead, coil, condenser,
or points for that cylinder may be defec—
tive.
5. Remove the spark plug, clean it
thoroughly, or replace it with a new one;
gap the plug to 0.7—0.8 mm (0.028—0.032
in.). Connect it to its cap, and ground it
against the cylinder head. Kick the
engine over briskly. The spark produced
should be thick and blue.
6. If there is no spark, or if the spark
is weak and yellow, repeat the test using
a piece of metal, such as a nail, inserted
into the spark plug cap and held about %
in. away from the cylinder. If the spark is
healthy, the problem was the spark plug;
if not, check the condition of the points.
Inspect, clean, and gap the points or re—
place them if they are badly pitted or
worn as outlined in the "Tune—Up" chap—
ter. If excessive arcing or sparking at the
points is noted while the machine is run—
ning, the problem may be the condenser.
A defective condenser will also cause
new points to wear out quickly.
If new points have just been installed,
a no—spark condition can be caused by
damaged or improperly installed insulat—
ing washers on the points wire terminal.
Check the points as outlined in Chapter
3.
7. If the problem is not in the points
or the spark plug, the spark plug cap
should be checked. Noise suppressor
caps are fitted, which are designed to
eliminate radio interference and provide
a hotter spark by means of a resistor in
the cap. Sometimes the—resistor breaks
down, and the cap then'becomes an open
circuit. Remove the cap from the spark
plug lead, and ground the end ofthe lead
against the cylinder head. If a fat, blue
spark is produced when the engine is
kicked over, the problem was the cap.
Replace it with a new one.
8. If the cap checks out okay, care—
fully inspect the cable itself. Check for
dirt or grease, cuts or cracks in the insula—
tion, moisture, etc. If the lead is dam—
aged, it must be replaced. This also in—
volves replacing the coil.
9. If the trouble has not been pin—
pointed, the ignition coil windings
should be checked for continuity, using
an ohmmeter.
a. Disconnect the two low—tension
coil leads (blue or yellow and
black/white) and check for continuity
between them. This is a check of the
primary winding. If there is no conti—
nuity, replace the coil;
b. Check for continuity across the
coil's blue or yellow low—tension lead
and the high—tension (spark plug) lead.
Resistance may be very high, but conti—
nuity must exist. This checks the sec—
ondary winding.
Even if continuity is present in the
coil windings, it is possible that the
coil is still defective. Replacing the coil
temporarily with one which is known
to be serviceable is recommended.
10. The condenser can be checked if a
capacitance tester is available. Con—
densers should have a capacitance of ap—
proximately 0.25 mf. Checking with a
'"megger'" (high—voltage ohmmeter)
should yield a resistance of 5m ohms or
better at 1,000v. Replace the condenserif
it fails either test.
NOTE: After testing, ground the con—
denser lead against the case to dis—
charge it.
As noted above, sparking at the points,
or points which pit or burn rapidly would
indicate a defective condenser. Bad con—
densers will cause mounds and matching
depressions on the points, as illustrated.
f ———
— a
3,
Excessive Capacity
Low Capacity
A defective condenser will cause mounds and
matching pits on the contact surfaces
11. If the trouble is a misfire, and the
tests above do not pinpoint the problem,
check the condition and operation of the
automatic timing advance unit as out—
lined in Chapter 3.
Charging Circuit
1. In the event that the battery over—
charges, check the battery itself, and the
voltage regulator.