...with a warm engine at 2,000 RPM...slowly add 1 cup of water to the intake over several minutes. It will remove all of the carbon from the rotor face and free up sticking apex seals in most cases.

My RV-3B had been sitting since last September. Finally put the prop on today. Two apex seals stuck. Got them loose by painting with ATF and poking with a plastic rod through spark plug hole.

I then tried the cup of water trick. May have removed some carbon, but seems there still are some deposits on the rotors.

Runs fine, but ...

Lynn, what is "a warm engine"?

I don't think my oil and water temps got much higher than 170F.

Finn