Re: Back firing

Posted by Re-run on Aug 22, 2010; 4:35am
URL: http://vintage-and-classic-hondas.81.s1.nabble.com/Back-firing-tp1270157p1270550.html

What air filter are you running? Your issue is in the idle circuit so you can leave the mains alone for now.
When the carbs were cleaned, did you do it or someone else? The issue with these bikes are the idle jets like to plug up, the manifold boots between carb and engine get hard and do not like to seal or they crack.
The high idle could indicate an air leak.

So if you can, get the manual from here and check out the carb section. See if you can pull out the idle jets and clean them by hand. Check the boots and look for cracks. A common way of doing this is to spray the boots with wd-40 and listen for changes in idle.
Also, check the idle knob when warm and back it out, idle should drop but if not then it has to be an air leak.
I know these carbs also have some sort of diaphragm and you may want to check those out.