1979 CB750K

[duke31267]

I recently purchased the above model and after cleaning the carbs meticulously it runs good.  However, there are three issues that I hope I can get advice on.  1) It seems like there is too much backfiring when the engine is decelerating.  2) When coming to a stop, the engine runs high throttle for about 10 to 20 seconds before it idles down to about 1200 rpm. 3) Every once in a while I hear what can be described as an air backfire or a hiccup of sort on the right side, sort of like the engine is throwing hte air back out of the airbox or somethign like that.  Does anyone have any advice on these three issues?  Could they all three be related?  Any advice would be appreciated.

[genesound]

Sounds to me like the insulators are leaking. That's what Honda calls the rubber boots between the carbs and the head. It's not uncommon for them to crack and leak after a carb removal. You can get new ones for about $15 each at www.ServiceHonda.com .

[sjackson]

I know this is a little late, but also check your air cutoff valves. They're supposed to temporarily block the slow air jet when you let up on the throttle at high RPMs, which is supposed to reduce backfiring on deceleration.