Posts: 147
Location: Milwaukee, WI | Always start with the spark plug your owner's manual recommends.
Have you had poor performance in the past ? If not, get a new set of what is installed in it currently.
There are usually a couple of part numbers of a given brand that are compatible with your motor. They are classified by "heat ranges". This is a subject to discuss with a good marine mechanic. They can examine the used plugs (BEFORE fogging)and can "read" visual clues about plug/engine compatibility. Your "style" of operation; the ratio of high speed vs low speed operation, has a bearing on what heat range plug is best.
I use the NGK brand that is listed in my owner's manual & have not had any issues so far. So, I stick with them. And, I don't throw out the used plugs. I put them in a baby food jar containing a mix of gasoline & carb cleaner & let them soak over the winter. I can clean them up with an old toothbrush next spring. That way, I cycle between 2 or 3 sets of plugs.
Also, pay attention to setting the correct gap on new spark plugs. Again, your owner's manual will have the gap specification for your motor.
Pay VERY close attention whenever re-installing the spark plugs!! If you cross-thread or strip the spark plug holes, its an expensive repair job due to the aluminum cylinder heads on most outboards. Use a torque wrench or only hand tighten them using a short lever-arm wrench. I put a small dab of anti-sieze compound on the threads of each plug.
Its a good idea to keep a new, spare set of spark plugs on-board your boat in case you have problems on the water. Sometimes, changing them where you're stalled will get you running again. |
