Before you take it apart, try this- - - -with the air pressure on #1, give the top of the exhaust rocker arm a few sharp raps with a dead blow mallet or a non-marring hammer of some sort. If there's a carbon deposit on the valve face or the valve seat, it's possible to dislodge the deposits and make a noticeable change in the amount of leakage. If you can make a noticeable difference, go to "Plan B"
Run the engine until it reaches normal operating temperature, and set the idle speed screw to a fairly fast idle speed- - - - -1500 RPM or so. Fill a Coke bottle with VERY hot water- - - -almost boiling, and slowly dribble it down the carburetor throat. When the hot water hits the combustion chamber it will flash to steam almost instantly and "steam clean" the combustion chamber, valves, valve seats, etc. It won't fix a burned valve, obviously, but if the problem is a carboned-up valve or seat, I've seen some pretty dramatic improvement, without ever turning a bolt!
Jerry
