4-13
E
EJU13431
Cleaning and adjusting the
spark plugs
The spark plug is an important engine
component and is easy to inspect. The con-
dition of the spark plug can indicate some-
thing about the condition of the engine. For
example, if the center electrode porcelain is
very white, this could indicate an intake air
leak or carburetion problem in that cylinder.
Do not attempt to diagnose any problems
yourself. Have a Yamaha dealer service the
watercraft.
Remove and inspect the spark plug peri-
odically; heat and deposits will cause the
spark plug to slowly break down and erode.
If electrode erosion becomes excessive, or if
carbon and other deposits are excessive,
replace the spark plug with the specified
plug.
Measure the spark plug gap a with a
wire thickness gauge. Replace the spark
plug or adjust the gap to specification if nec-
essary.
To install the spark plug:
1. Clean the gasket surface.
2. Wipe any dirt from the threads of the
spark plug.
3. Install the spark plug, and then tighten it
to the specified torque.
4. Install the spark plug cap.Standard spark plug: BR7HS
Spark plug gap:
0.6–0.7 mm (0.024–0.028 in)
Spark plug tightening torque:
25 N·m (2.5 kgf·m, 18 ft·lb)
E_F1N-70.book Page 13 Tuesday, April 26, 2005 12:03 PM
