Re: Seafoam
Probably not, but it doesn't hurt to run some through it. If nothing else, you'll clean some carbon out of the motor.
I also like BRP "Engine Tuner." It does the same thing as Seafoam, but you don't have to mix it with the fuel. My usual procedure, is to pull the plugs, squirt some into each cylinder, replace the plugs and then let the motor sit overnight. The next day, I run the motor, applying Engine Tuner to each carb in rotation, until the cylinder being sprayed begins to falter. I then move on to the next carb and repeat the process, until I have emptied the aerosol can.
Like with Seafoam, this will result in lots of white smoke, but the stuff works quite well.