Yamaha XS650 Series, Shop Manual

Page: 60 / 215

6-4. 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 of
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 he 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.
A. How to “Read” a spark plug (condition)
1. Best condition: When the porcelain
around the center electrode is a light tan
color.
2. If the electrodes and porcelain are black
and somewhat oily, replace the plug with
a hotter type for low speed riding.
3. If the porcelain is burned or glazed white
and/or the electrodes are partially burned
away, replace the plug with a colder type
for high speed riding.
B. inspection
Instruct the rider to:
1. Inspect and clean the spark plug every
3,200 km. (2,000 mil)
2. Clean the electrodes of carbon and adjust
the electrode gap.
3. Be sure to use the proper reach plug as a
replacement to avoid overheating, fouling
or piston damage.
Spark plug type: N-7Y (Champion) or
BP7ES (NGK)
Spark plug gap: 0.7 0.8 mm
(0.027 0.031 in)
6-5. LIGHTING AND SIGNAL SYSTEMS
A. Lighting tests and checks
The battery provides power for operation of
the horn, tail light, stop light, neutral light,
and flasher light. If none of the above
operates, always check battery voltage before
proceeding further. Low battery voltage
indicates either a faulty battery, low battery
water, or a defective charging system. See
section 6-2 Charging System, for checks of
battery and charging system. Also check fuse
condition. Replace any “open” fuses. There
are individual fuses for various circuits.
1. Horn does not work:
a. Check for 12V on brown wire to horn.
b. Check for good grounding of horn (pink
wire) when horn button is pressed.
2. Stop light does not work:
a. Check bulb.
b. Check for 12V on yellow wire to stop
light.
c. Check for 12V on brown wire to each
stop light switch (front brake and rear
brake switches).
3. Tail light does not work:
a. Check bulb.
b. Check for 12V on blue wire.
c. Check for ground on black wire to tail/
stop light assembly.
4. Flasher light(s) do not work:
a. Check bulb.
b. Right circuit:
1) Check for 12V on dark green wire to
light.
2) Check for ground on black wire to
light assembly.
c. Left circuit:
1) Check for 12V on dark brown wire to
light.
2) Check for ground on black wire to
light assembly.
d. Right and left circuits do not work:
1) Check for 12V on brown/white wire
to flasher switch on left handlebar.
2) Check for 12V on brown wire to
flasher relay.
3) Replace flasher relay.
4) Replace flasher switch.
e. Check flasher self-canceling system.
(Refer to flasher self-canceling system.)
5. Neutral light does not work:
a. Check bulb.
b. Check for 12V on sky blue wire to neutral
switch.
c. Replace neutral switch.