Agreed, I had them out and did the paper test. I will be making the manometer soon so will use that. Can't respond to the butterflies being centered but they looked good and the paper test gave the impression they were so close to each other only a manometer will know a difference. I will build one by next weekend. the mixture screws you speak of, are they the ones under the brass plugs. I did pull the brass ones out during the carb cleaning. I will have to re-read the "dead cylinder" thing.
Yes, the mixture screws came with a little cover over them, so remove them if they are still there.
If the paper feeler gauge test was done right with equal drag, and the butterflies are closing fully, then you should be able to have the engine idle at 1200 rpm or even much lower.
The "dead cylinder" is not hard to do. I recommend you use a spare spark plug that you can make up with an alligator clip and a short piece of wire, as shown in my pic. For the cylinder that you want to be dead, disconnect its spark plug wire, and connect the spare plug to the spark plug wire. This is done so that the ignition coil has its normal electrical path for the high voltage, and prevents damage to the ignition coil. Make sure the alligator clip stays clipped to one of the engine cooling fins.
Good idea to warm up the engine, running both cylinders, for a few minutes before you start. Then shut off the engine, and install the spare spark plug/wire/alligator clip. You should have a fan blowing air across the engine to help with cooling. If you remove the single bolt at the back of the fuel tank, you can then lift the back end of the fuel tank upward slightly, giving enough room to use a small screwdriver to adjust the mixture screw.
To do the "dead cylinder method" you must adjust the "idle mixture screw" (pilot screw) as well as the "idle speed screw". You should be able to adjust the engine speed down to around 300 or 400 rpm on 1 cylinder firing. If you can't do that, then you're not doing it right,or you have air leaks etc. You have to adjust both screws to achieve this. As you adjust the pilot screw, keep lowering the idle speed screw to get the rpm down. Adjust the mixture screw for the best, highest idle, that you can get. ( with the single cylinder at only 300 to 400 rpm). It can be hard to detect, but go in and out on the mixture screw, sensing the engine rpm falling off in both directions.
The important thing to realize , is that the throttle butterfly must be almost completely shut, in order that the pilot screw can be adjusted. This is because the butterfly must be covering up the 3 by-pass holes in the carb throat. If the butterfly is open to much, the mixture coming through the 3 by-pass holes over-rides the pilot screw, and you are unable to adjust it.
