Another idle problem on a rebuilt 84 Interceptor 500

I have been recovering an 84 Interceptor 500 that suffered a carb fire, burning most of the rubber and plastics in the carb area, including airbox, carb choke linkages and tubes, etc. Got replacements for most everything (trying gravity feed as the fuel pump is also bad), rebuilt the carbs (twice) and got her running today from the tank. Started easy with choke, came off choke with little problem, revs fairly clean, but I cannot get the idle to hold at about 1100 without holding a tiny bit of throttle. Think I have my Idle Adjust Screw (also replaced as the black twist knob melted off) fully turned in, but the rpms drop off and she dies if I let off the last bit of throttle. Basically, I am acting as the Idle Screw, but using the throttle. Pilot screws are at 2 turns out. New carb boots. Don't think (?) I have any vacuum leaks, as the bike idles fine at 1000-1100 with me holding a bit of throttle. Any thoughts on things I missed and need to check or correct? Fab up a longer Idle Adjust Screw? Thanks

 

???? i doubt a longer screw will cure that problem. instead i'd check that synch is close.

 

I synced the carbs based on equalizing to the first port, rather than the paper pull method. Just wanted to get it close enough to run. Think this would cause the inability to idle?

 

no, good job on the synch. could be the rare case of "false idle". sure float levels are correct ?

 

Rechecked them during the second carb clean. Didn’t get the slow jets well enough the first time. Only minor adjustments needed on the floats.

 

I am leaning on the idle circuit being in need of attention. That circuit has very tiny opennings and needs that extra attention you mention. The moment you use the throttle you are basically bypassing that idle circuit.

 

Problem solved, and of my own doing! I mentioned that I had replaced the Idle Adjustment Screw as the plastic knob of the original screw melted off. I did it on the bike as part of my last thrash, but without really being able to see anything. But I forgot that the screw bears on a spring-loaded cam. When I removed the original one, the cam rotated up and out of the way, so the new screw wasn't impacting it at all. So no idle adjustment! Removed the carbs (for the fifth time!!), and corrected my error once I could see it all. Idle issue solved. Bike now idles and runs fine. Took it out for its first extended road test, and it ran very well. The tach even started to work again, so I now have a fully functioning gauge cluster! So on to the rebuild process (brakes, suspension, cosmetics). But looks like the core is good! Thanks for the input.

 

Excellent!!!!!! I bet you can pop those carbs of in 15 minutes now.....

 

Yup, I have gotten really good at it!