Carb cleaning; what am I missing?

[Cadapult]

Sorry for what will be a long post, but I need some advice. I've had the carbs off my '82 Maxim 5 or 6 times now (I've lost track) with cleaning, replacing o-rings, cleaning, adjustments, and more cleaning. My baby still won't run quite right. Starts easily with the choke on, but will stall the minute I touch the throttle. A spritz of carb cleaner in the intakes & the idle increases 300-400 rpm and I can hit the throttle and wind it up to 5k-6k. As long as I don't let off the throttle completely it'll run along fine, but let off the throttle and it idles back to 800rpm and dies if I try the throttle again.
I've got good flow thru the air screw ports, the three little bypass holes in the throats, and every removable jet is clean and clear. The pistons and diaphragms are perfect. I hooked a shop vac to the inlets and the pistons would rise to match the vacuum. Every passageway seems clear. The only openings I'm not sure I'm getting carb cleaner/air thru are the brass tubes (overflow?) that project down into pockets in the float bowls.
From what I've been reading here my suspicion is it's running lean. Would an engine without the air filter installed run as I described? I had corked-up all the leak points at the air box, with no change. Adjusting the air mix screws out between 2 and 4 turns doesn't make a difference. I'm at a bit of a loss, and hope one of the pro's here has some suggestions.

 

[lhaolpa]

These carbs are hard to get clean once dirty.Did you remove the emulsion tubes under the main jets?They must be clean,and I mean clean!. From your saying that spraying carb cleaner on the carb mounts and it reved,says to me that you have a leak at the mounts.The mounts are available on ebay and on Mikesx,and other places. Good luck. lha

 

[bcware]

I would suspect the float height is your problem.

 

[Cadapult]

I've had the emulsion tubes out and cleaned them, and made sure all the pinholes along the sides were clear.
When I sprayed carb cleaner on the carb mounts (manifolds) there was no change to the rpms. It was when I sprayed into the carbs themselves that I could open the throttle and rev the engine. The mounts look perfect & have new o-rings.
I haven't checked the float height yet; I have to figure out how to hook some tubing to the bowl drains. I hadn't thought the fuel level in the bowl would make my bike run like it does, but I'll try to check that today. Thanks guys-

 

[bcware]

The float height is really important, but before you button everything back up check the height with someone on here. Often the manual values are wrong.

If there is not enough fuel in the bowl you'll die when you open the throttle and possibly at idle without using choke. You're basically starving the engine of fuel under all conditions.

Other suspects would be the vacuum hose of the petcock, dirty or rusty fuel/tank, and a gas cap that is not venting properly.

 

[lhaolpa]

I've had the emulsion tubes out and cleaned them, and made sure all the pinholes along the sides were clear.
When I sprayed carb cleaner on the carb mounts (manifolds) there was no change to the rpms. It was when I sprayed into the carbs themselves that I could open the throttle and rev the engine. The mounts look perfect & have new o-rings.
I haven't checked the float height yet; I have to figure out how to hook some tubing to the bowl drains. I hadn't thought the fuel level in the bowl would make my bike run like it does, but I'll try to check that today. Thanks guys-

By what you're saying,there is some blockage in the idle circuit somewhere.I had a blockage like you're talking about,and ran a tip cleaner down into the little tube,and with a good blast of air,it came out. Some have cautioned about using such things as a tip cleaner for a torch on carbs,but as I was perusing a website,in the tools page I saw a tip cleaner repackaged as a carb tool,so there is room for discussion on that matter.I've used a tip cleaner for years for unclogging passages and jets in carbs,with good results.You just have to use common sense,as the old saying goes"he could f%#k up a 40# anvil with a rubber mallet".Don't do that. lha