Backfiring My bike started backfiring, especially during acceleration, then as I was "cruising" at 3000-4000 RPM it would suddenly surge to 5000-6000 RPM with accompaning acceleration. I've cleaned the carbs from sitting up, adjusted the valves, changed the oil, & put in a new battery. It starts right up & idles nicely at 1000-1200 RPM when warmed up. I've only put about 10-15 miles on it running around in a big parking lot, and haven't gotten it up over about 40 mph yet since I don't have it inspected or registered. Could it just need to be "blown out" with some high speed running, or could there be a carb or ignition issue?

Hi, maybe its the same problem i had, i have a 1200 goldwing where your spark plug are there are holes if these become clogged the water stays there and causes backfiring, get a metal welding rod or steel coat hanger and push through the hole to clear the water, hope this helps good luck.
regards Mark

Sounds like the electronic ignition may be loose.

Sounds like you've got a carb with a clogged jet. My guess is that the surging was a moment where the carb was actually operating well enough for the bike to run properly on that cylinder. Could also be a spark problem but you should be able to determine if this is the case rather quickly. I'd probably go ahead and replace the plugs if you haven't already...that could help...but my guess is still going to be carbs.