Spark Plug; Lighting And Signal Systems; Lighting Tests And Checks - Yamaha YT175J 1982 Service Manual

Primary coil resistance
Secondary coil resistance
Set the tester Set the tester
"x 1 Q" position "x 100Q" position
1.0Q ± 10%
5.9KQ±20%
at 20°C (68°F)
at 20°C (68°F)
Spark plug
The life of a spark plug and its discoloring
vary according to the habits of the rider. At
each periodic inspection, replace burned or
fouled plugs with suitable ones determined
by the color and condition of the bad plugs.
One machine may be ridden only in urban
areas at low speeds; another may be ridden
for hours at high speed. Confirm what the
present plugs indicate by asking the rider how
long and how fast the rides. Recommend a
hot, standard, or cold plug type accordingly.
It is actually economical to install new plugs
often since it will tend to keep the engine in
good condition and prevent excessive fuel
consumption.
1. How to "read" a spark plug (condition)
a. Best condition: When the porcelain
around the center electrode is a light tan
color.
b. If the electrodes and porcelain are black
and somewhat oily, replace the plug
with a hotter type for low speed riding.
c. If the porcelain is burned or glazed white
and/ or the electrodes are partially burn-
ed away, replace the plug with a colder
type for high speed riding.
NOTE: _ _ _ _ _ _ _ _ _ _ _ _
First check for ignition timing and intake air
leaks before changing spark plug types.
2. Inspection
Instruct the rider to:
a. Inspect and clean the spark plug at least
every 6 months.
b. Clean the electrodes of carbon and ad-
just the electrode gap.
c. Be sure to use the proper reach plug as a
replacement to avoid overheating, foul-
ing or piston damage.
Spark plug type: BP7ES (NGK)
Spark plug gap: (use wire gap gauge)
0.7 - 0.8 mm (0.028 - 0.031 in)
6-3
LIGHTING AND SIGNAL SYSTEMS
Lighting tests and checks
1. A.C. Circuit Output Test
With all A.C. lights in operation the cir-
cuit will be balanced and the voltage will
be the same at all points at a given
r/min.
a. Switch Pocket Tester to" AC20V" posi-
tion.
b. Connect positive
(+)
test lead to Yellow
connection and negative (-) test lead to
a good ground.
1. Set the tester" AC20V" position
c. Start engine, turn on lights and check
voltage at each engine speed.
If measured voltage is too high or too
low, check for bad connections, damag-
ed wires, burned out bulbs or bulb
capacities that are too large throughout
the A.C. lighting circuit.
Output voltage:
6.0Vor more/3,000 r/min
8.3Vor less/8,000 r/min
Color: (Y - B)
NOTE: _ _ _ _ _ _ _ _ _ _ _
This voltage test can be made at any point
throughout the A.C. lighting circuit and the
readings should be the same as specified
above.