In a perfect world, these little guys need to be rich to run right. If you start with one adjusted properly, and you lean it, the idle speed will increase. No doubt about it! Don't go for a smooth running engine on idle. That will leave you lean every time. When right, the engine will be a little unsteady actually, maybe not even hitting on every compression stroke. Doesn't sound good, but we're talking about a single cylinder 2 stroke. They're just that way on the idle...

Not saying there's no chance of something else going on.

Peak at wide open, then richen until you just start to loose rpm. On idle, go for your smooth/quick transition. Fly, and adjust as necessary. -Al