Reply To: Newer Yamaha 50 HP 4-stroke question

[David Stanton]

I took a look at this motor and found #2 spark plug was somewhat wet with gas after having not been run for about 10 days. The other three plugs looked good. All throttle/carb linkage checked out OK. I replaced the wet plug with an old plug that looked good. Before putting it in, I grounded it and cranked and it had healthy spark in its gap (I didn’t have a way with me of looking for a longer spark in free air). It seemed to idle OK , but this was all I could do in the driveway. The next day, my friend took it to a lake and it still would only go about 3/4 speed. Based on all this, I suspect #2 cylinder’s carb has a problem. He dropped it off at a dealer Saturday. I’ll let you know when I hear what they find. I’ve never been afraid of carbs on cars or motors, but my friend is a particular guy and I didn’t want to be learning these carbs on his motor.
Dave