I have one of these engines myself, it has about 2 gallons on it and I am very pleased with it so far. I have a couple of questions for you if you do not mind to answer them:
About how many gallons of fuel do you run through your engines before you do a complete breakdown and clean?
What do you use to clean it with as far as chemicals?
In my opinion, I do not think it is ok to clean the piston and sleeve with chemicals such as brake cleaner, it seams to strip off some of the necessary residue causing the enigine to leak off pressure if held at top dead center once you put it back together. Let me know what you have experienced.
And one last question, if you do not mind to let me know what your carb settings are at, thousands of an inch would be great. Make sure to mention if the head of the needle is above or below the needle barrel and please include your idle set screw. I measure mine directly next to where it threads into the plastic case.
I know this is alot to ask for but if you could I would appreciate this information.
Thank you and May God bless you. Romans 10:9-10