Running a little rich, fouling plugs 2000 Honda Elite 50

[gravano]

I had my scoot rolling almost all summer. But she backfired signaling her anger at me and then wouldn't start.
Plug was pretty black. Replaced, but to no effect.
I'm trying to figure out what's making it run so rich.
I put a new throttle cable on -- should I check that?
It's got a pollini head I think 70cc or so, but I switched back to the original main jet to get it running leaner.
The air mix screw is out farther than it prolly should be.

Anyway, can't figure out why it runs so rich and never cared too much because I could just replace the plug, but it seems to be more of a pain now.
Any advice is appreciated. I'm in Chicago but want to stretch another month out of the season!

[bakaracer]

Stock carb or aftermarket?

[gravano]

Stock carb. Actually it's new. I got it on ebay.

[bakaracer]

Is for your model bike and a oem honda part? Or generic universal scooter carb?