Oh, I'll probably get the 15 going again, (did I mention I'm stubborn?) just have to find a decent P/C for reasonable $. Should have done a thread on the tear down, but I'm a bit ADD right now and have three saws in various stages of assembly. Can't figure out where my priorities are I guess, but it's a hobby, stress reliever so I just pick up what I feel like at that time.
I already have a full stable of runners.
On your 20, after revving it, it idles for a bit then dies? Does it just sort of tail off? Or does it rev a little erratically before stalling?
Could be an air leak at the manifold. Check the mating of the carb to the manifold and manifold to intake port on the cylinder. Make sure to torque the screws down enough to seat it, just be careful not to over do it (steel screws & AL cylinder). Also, if you've been able to run it a bit, check the plug. Specifically the color of the electrodes. (Light brown = good, black/wet = rich, white/grey = lean)
Don't know about the rep # game, but you've got me once. It's all good.