Yanked the carbs off to replace cheap chinese fuel lines with some motionpro tygon. While they were off, noticed that the connecting tube rubbers were wasted. Tore carbs apart, replaced the junk bits, re-assembled, and put it all back together. Hanging idle issue presents itself. Turns out that in my hurry to reassemble carbs, I didnt tighten the fuel slide connecting rod screws. Took it back apart...fixed...put back together.... sigh.... shouldda bought the good fuel line to begin with.
I've had that, recently.
Not so much with Chinese fuel lines, but some NOS genuine Suzuki line. I suspect it was wrongly packed and sold as fuel line, but it was actually a water drain hose, so wasn't up to prolonged exposure to modern gasoline. It had the genuine Suzuki part number on the package, and I'm sure it was the real thing, just the wrong item in it.

