A few days ago, my '83 R65 backfired twice through the right carb while I was trying to start it. I added more choke and it fired and ran nicely... except: Now, after about 20-30 minutes of riding, when the engine is hot, it doesn't want to settle down to a regular idle. If I am slowing or stopping, the bike will hold its RPM when the clutch is in, even if the throttle is closed. If I downshift and let the brakes bring the engine below 2,000 RPM, I can pull in the clutch and the engine will settle down to its normal (800-900RPM) idle. Upshifting is fun, because when I accelerate and pull in the clutch for an upshift, the engine stays at the RPM it was at in the lower gear until I let the clutch out.

The Bing carbs were re-built about 400 miles ago by Re-Psycle in Lithopolis, Ohio and up until the backfire there were no problems.

Could the backfiring have stretched a diaphragm or messed anything else up? Any and all ideas and suggestions will be greatly appreciated