Yamaha XZ550RJ 1982 Owner's Manual page 215

CAUTION:
Avoid touching the glass part of the
bulb. Also keep it free from oil stains;
otherwise, the transparency of the glass,
life of the bulb and illuminous flux will be
adversely affected. If the glass is oil
stained, throughly clean it with a cloth
moistened with alcohol or lacquer thin-
ner.
- 203-
WARNING:
Keep flammable products or your hands
away from the bulb while it is on,
because it heats up. Do not touch the
bulb until it cools down.
e. Reinstall the light unit assembly in the
headlight body. Adjust the headlight
beam if necessary.