I have a Dixon 503 with a 20 HP Onan. I was having difficulty getting
it started so I took the carburator apart and cleaned it because it
had a bunch of what looked like varnish in it. I also cleaned out the
fuel tanks and fuel lines. Now the engine starts and runs, good
enough to mow, but does not have the power that it used to have. I am
afraid that when I put the carb back together I may have some of the
ports installed inproperly. Does anyone know how to adjust the carb
on that Onan? Specifically if there are any requirements that I need
to be aware of with the two port tubes that can be removed?

One more symptom to consider. When it is running, it is running very
rich, and I actually ran it out of gas today. Just before it ran out
of gas, it seemed to get a big power boost and ran like a champ for
about 10-15 seconds, then it ran out of gas.

Any help or advice would be greatly appreciated.

Dave