[Vinny Intrieri]

Ok so i got a 92 Nighthawk CB750 bobber that runs too high at idle. Without the choke on fully warmed up it sits at over 3000rpms, so i turn the choke up slightly to bring ir down within the specified range. I rebuilt the carbs and set everything back to stock. The problem lies I believe in the butterfly valves. How far open should they be when sitting at idle? I feel as though there should be some kind of a spec for this. Being that they are CV carbs i think having them completely closed is putting to much pull on the carbs thus dumping too much gas, causing it to sit at too high of an idle speed. If anyone knows how far open the butterfly valves should be, please let me know

 

[cmonSTART]

The opening is usually set by adjusting the idle setting to 800-1000ish RPMs, and by synchronizing the carbs. Wherever you have nice even vacuum across all cyinders and a nice idle RPM is where they stay. Tweak them so they're even and pretty much closed, then make the adjustments to sync and idle RPM.

 

[FlipFlop]

All the multiple carbs I have ever dealt with had specs on the butterfly, if I remember correctly, mainly so that they are open and close at the same time and get the same flow. So basically was listed as more of a tolerance +/- .oo1 or something to that affect.