Running on one cylinder?

[RyalsCreek]

My boat was running fine and then it suddenly ran much slower, about half speed is all it will go. I know only a little bit about motors, but have a hunch it might be running on one cylinder. (it's a 40 hp 2 cylinder 2 cycle) Is there a way to determine if it is running on one cylinder without possibly damaging the motor? I was contemplating alternately disconnecting the spark plug wire for each cylinder. If it is only firing on one, I guess I could check the compression next to see if one cylinder is burned out.

 

[TOHATSU GURU]

Re: Running on one cylinder?

Removing one wire at a time is the time tested method.