Topic: Alright, alright I need carb help

[eigenvector]

I held off for a long as I could, but I just can't figure this one out.

Carb bank on my Nighthawk, they're Keihin VE65s, rubber diaphragm, enrichment circuit - not a butterfly choke.

Start the bike with choke - it starts right up and idles at ~1200rpm.  Doesn't matter what temp the engine's at, it never climbs above 12 to 1500 rpm.  Plugs are black and wet, but since choke is on I'm not too surprised.  Idle is very stable and regular - no coughing, hesitation, stumbles.

If I give it any throttle, I mean the slightest throttle - instantly dies.  Doesn't even sputter or cough - dies at the instant of throttle.

Originally I thought - 'hmmm, pilot circuit is plugged up'  But it if is, I sure can't find it.  Air will move through the passages, carbs themselves were totally disassembled and soaked overnight in Berryman's.  Jets are all as clean as I could make them - air will pass through them, as will a fine wire.  Diaphragms are intact, they move up and down smoothly.

I know that the enrichment circuit is designed to cut out as soon as throttle is applied, so that tells me something's haywire with the pilot circuit - I just don't know what.  When I pulled the bowls, the fuel level appeared to be acceptable.  I don't know if the bowl overflow vents are working - it doesn't have a traditional overflow tube, to be honest I don't know how it works either.

[70CB750]

I just had this crazy vision of Kill Switch wiring messed up at the right control - moving the throtle handle will shorten it up.

[eigenvector]

Jesus I hope that's it 

Be a riot if it was, but I'm doubtful.

I'm going to tighten it up today - get as many air leaks out of the system as I can.  Just doesn't feel like an air leak though.

[eigenvector]

Quite a day of victory for me. 

I learned something that I guess was in the back of my mind but just didn't think it would be the case.

This bike will not absolutely will not start and run without a pressurized fuel line - that is it requires the fuel line to be full and the petcock to be opened.  I was doing all my troubleshooting from a remote tank, and so as to not waste fuel or get gas all over the place I was filling the line just to flood the carbs, then closing the petcock.

Nope!  That petcock must be open.  Once I did that the choke began to do it's job properly.  I could even give it a little throttle - turns out maybe (bike isn't cool enough to touch yet) I have a couple cylinders not responding.  Not sure if it's vacuum leaks or the enrichment plunger not responding properly.  The outside plungers are sticking open because the rod that connects them is twisting excessively.