Reply To: Newer Yamaha 50 HP 4-stroke question

[billw]

I have to admit that I have seen an NGK plug “go bad” or at least, terminally foul, every once in a great while; so it is worth a shot…but it’s quite rare.

Those carbs are also difficult to trouble shoot. With a two stroke, if you have a lean carb, you can just take a pump oil can full of two-stroke mix and shoot it down the throat of each carb. If the speed picks up, there’s your lean carb, and proof that a carb job is justified. That trick is nearly impossible to do on the Japanese four strokes.

Long live American manufacturing!