[Easy Rider 2]

You could very well have a leak. Inspect all the fittings. Also you should try spraying some lube through the cable. It could be dirty and hanging up.

Also you could just have a "proceedure" problem.

The idle speed should be set ONLY when the engine is thoroughly warm (HOT) and then you maintain useable idle speed when it is COLD by using partial choke.

Do you have a stock air box and filter on it ?
Have you done any cleaning on the carb(s) ??......like some good cleaner in with the gas ?? Could be a gunked up idle jet too.