Hi All
Good advice on cleaning the carbs. We need to understand that the idle jet, while small and you might start and still idle, if not completely clear can give you a lot of problems. The idle jet does not stop flowing at some magic RPM, it contributes to the total flow overall. it is primarily the fuel delivery at starting and idle speeds and is very important at the leanest positions, say 3500 to 4500 RPM. Fuel varnish can also contaminate the main jet and create a much leaner mid range also. it may appear to run OK at full power but you can be very lean in mid range. (look for high MAG drops in that case) Carbon on the spark plugs can also be an issue, check to see if the tip and electrode are clean.
I love fresh fuel as others have noted, best to always put new fuel in after it sat for 3 or 4 weeks or more. If you can top up with some 100LL avgas remember that it has about 20% toluene and that is a great solvent to clear up the small passageways in the carb itself.
Cheers
