Hey tom, I see your post and I will obey.
Jimmy,
I think you hit the nail on the head. The problem described in the article is exactly what sounds like I am experiencing. For one thing - I have gasoline in my tanks that may be even over a year old in one of the tanks.
Another thing - my motor is very very low use - I would be surprised if it has even more than 20 miles on it at high speed and maybe half that at 5 knots. I use the motor VERY LITTLE - so it does indeed sound like it's running rich because it's only used to idle out of the harbor for the most part. I have probably sailed hundreds of miles in 'boat' over the past three years but I would guess I have motored less than 25 miles total in the same period of time. Since the motor is always going real slow it's probably building up crap like the article said:
"This black soot is usually an indication of an engine that is running too rich"
The gas was so old about 2 years ago I drained it out and put it in my car so I could get new gas for the boat. I have been notorious for having gas on board that is over a year old - (I guess I should stop doing that).
The article describes the problem to me:
"If the boat has not been run in a long period of time, then the gasoline becomes stale and loses some of its octane. This will cause the engine to become less efficient in burning the gas and oil mixture, which will result in the black oily residue in the exhaust chamber."
I know what gear oil looks like from putting it in my differentials and I know what grease looks like from greasing my trailer hubs and I know what oil looks like from changing the oil on my car. This gooey stuff did not look like any of that - it did indeed look like that crap that would be created from a heat process - something that could flow when hot but becomes stiff when cool - that sounds like the crap from the engine that is described in the story that Jimmy sent (thanks Jimmy) also there was very little of the stuff and it was inside the prop exhaust because you guys taught be a long time ago that the middle of the prop is also the exhaust pipe so now I know where the exhaust is and that's where the gooey stuff was.
I guess I need to do what that story said to the carburetors? (I thought these motors were injected? shows how stupid I am about modern motors
) Well, they gotta use air to run so there must be a hole for air to go in somewhere, right?
The story says I can squirt stuff into that air hole to make the exhaust clean:
"The process of cleaning and de-carbonizing the inside of your engine is very simple. It does not require any special tools. You do not have to disassemble the engine block to do any of this cleaning.
All you have to do is purchase a can of engine de-carbonizing spray from your local dealer and follow the directions on the can. Most engine manufacturers sell this product. They all have a different name for it. Mercury calls theirs Power Tune, Evinrude calls it Engine Tune. I am not sure what name Yamaha gives theirs, but they also have one.
The process is fairly simple. You remove the air silencer from the front of your carburetors. This will expose the throat of each carburetor so that you can spray the cleaner directly into the engine. Make sure you have a suitable water supply to your engine, and run it for several minutes to get it up to normal operating temperature. You then increase your throttle in neutral to approximately 2,000 rpm.
At this point, you spray the cleaner directly into each carburetor throat. You will spray each carburetor approximately 10 seconds, and take turns from one carburetor to the next until you have used the entire can of cleaner. Now turn off the engine and let it set for approximately 15 minutes. Restart your engine, and let it idle for another 15 to 20 minutes to burn off the leftover cleaner and flush out that oily sludge.
This product not only cleans out the exhaust build up, but it also cleans gum and varnish build-up from the ring grooves on the pistons, and will help extend the life of your engine."
this is silly.
)
). 
