Yamaha JT1 Series Service Manual page 76

ELECTRICAL SYSTEM-Charging System, Battery
1. How to "read" spark plug (condition)
a. Best ...... When the porcelain around the center electrode is a light tan color.
b. If the electrodes and porcelain are black and some what oily, replace the plug with a
hotter-type for low speed riding.
c. If the porcelain is burned white and/or the electrodes are partially burned away, replace
the plug with a colder-type for high speed riding.
2. Inspection
Instruct the rider to:
Inspect and clean the spark plug at least once a month or every 1,000 km. (600 miles).
Clean the electrodes of carbon and adjust the electrode gap to 0.5-0.6 mm. (0.023 in.)
Be sure to use standard B•7HS plug as replacements to avoid any error in reach or heat range.
0.5-0.6mm
(0.023
;n.l
5-11 Lighting and Signal Systems - JT2
The lighting and signal systems consist of the horn and stop light (power source-battery)
and the head light, tail light
and
meter lamps. (Power source-flywheel magneto.)
1. Head light
The head light has two 6V, 1.5W bulbs, and a 6V, 1.5W neutral pilot light on its top. A
beam directing adjusting screw is fitted on the right side of the- light rim so that the
horizontal direction of the beam can be adjusted (not vertically).
2. Tail Light and Stop Light
A 6V. 5.BW tail light and a 6V, 17W stop light are mounted. The lens of the tail light is
provided with reflectors on its three sides-rear, right and left.
3. Horn
The horn is a 6V, flat type, and has a tone-volume adjusting nut on its back.
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