Yamaha RD250(D) Betriebsanleitung Seite 84

Spark plug inspection
The spark plug is an important engine c o m -
ponent and is easy to inspect. The c o n d i t i o n
of the spark plug can indicate something of
the c o n d i t i o n of the engine. Check the colora-
tion on the white porcelain insulator around
the center electrode. The ideal coloration at
this point is a medium to light tan color for a
machine that is being ridden normally. If a
spark plug shows a distinctly different color,
there could be something wrong w i t h the
engine. F o r example, a very white center
electrode procelain color c o u l d indicate and
intake tract air leak or carburetion problem
for that cylinder. D o not attempt t o diagnose
such problems yourself. Instead, take the
machine to y o u r Y a m a h a dealer.
Y o u should periodically remove and inspect
the spark plug because heat and deposits will
cause any spark plug to slowly break d o w n
— 82 -