Yamaha RD200 1977 Betriebsanleitung Seite 89

You should, however, periodically remove
and inspect the spark plug because heat and
deposits will cause any spark plug to slowly
break-down and erode. If electrode erosion
becomes excessive, or if carbon and other
deposits are excessive, you should replace
the spark plug with one of the proper type.
Standard spark plug: NGK B-8ES
Spark plugs are produced in several different
thread lengths. The thread length (reach) is
the distance from the spark plug gasket seat
to the end of the threaded portion. If the
reach is too long, overheating and engine
damage may result. If the reach is too short,
spark plug fouling and poor Performance may
result; also, carbon will form on the exposed
a. Spark plug reach a. Longueur de filetage a. Zündkerzen-Gewindelänge
b. Spark plug gap b. Ecartement des electrodes b. Zündkerzen-Elektrodenabstand
- 7 9 -