Motorcycle Repair: slow return to idle and eventually dies, yamaha tx500, vacuum leak

Question
I've got a 74' yamaha tx500. It runs perfect when it is moving, but when I come to a stop and pull in the clutch, the engine takes a few seconds before returning to idle speeds and will stall if I don't keep reving it. The idle speed is fine. I think it may be running lean, or maybe the timing is retarded.

It starts right up and idles fine when cold (choke on). Runs great without choke as well, but after it warms it thats when the problems start.

Could this be a vacuum leak? Perhaps it is in need of some carb adjustment? Should I raise the needle a notch?

Answer
Hi Josh.

Don't tinker with the carb just yet.

First thing to check is the timing.  Make sure that it's right.

Next check the mixture.  Pull the plug and match it against the chart in the repair manual (you do have one, don't you?) and see if it's in need of adjustment.  Adjust as needed if needed.

Start with that.
Good luck and ride safe.
FALCON