I have the subject motor and I just cannot get the carb set right. At one time I was able to get the motor started, but then after a minute the rpms would start increasing until they got up to somewhere around 1500-1800. Then I would lower the idle speed and it would run. But if I stopped it and let it set for more that one minute it would not start again until I backed out the idle speed adjustment screw again. Then I would have to go through the whole thing again.
Now, I am at the point where I can get the motor to start every time (almost) and the rpms remain stable, but I think the mixture is way too rich. And, if the engine does not start on the very first pull on the rope I could be there for a while. When it does start I can take a clean white paper towel and place it near the exhaust hole just under the top cover and in just a second or two there will be a black area on the towel. It doesn't matter if I do this immediately after starting the engine, or after it has been running for several minutes, the result is the same.
So my question is, how do I lean the mixture on the carb? To make things more difficult for you, this is the "Bodensee" engine (or "Bondensee" if you prefer). There are only two adjustments that I have found and I just cannot seem to get the correct setup. No matter what I do, the mixture seems to be too rich.
Thanks in advance,
1996 Mercury 9.9HP 9.9MLA4ST serial 0H008826