Carb Synch Nightmare!

[2maxowner]

I own 2 Vmax's. I've had one of them for 16 years and the other, more recently. I have rebuilt and synched the carbs a couple times in the past and each time, the bikes ran good enough with the choke off to be able to effectively synch them.
This time, however, it's a nighmare. They synched fine and ran great for a couple days and then that's when they fell apart literally. I have been trying for the last year on and off to get the bikes to run with the choke off so they can be synched...but no luck whatsoever.
I have taken the carbs apart probably 4 times EACH to make sure I didn't miss anything. All the float levels ars fine and there ar eno spark issues. I am a very experienced cycle mechanic, I've been working on bikes for 30 years and these two have me stumped.
Is there a place that I can send the carbs to get them set to where they are all pulling the same vacuum...I know each cylinder may be a bit different. I'm at my wits end...how can I get the bike to at least idle with the choke off?:bang head: Please help!

 

[maleko89]

Is the idle thumb screw on the left side set right? Make sure each throttle plate is open a tad, otherwise excessive vacuum and the bike will stall.

When you rebuilt the carbs did you remove the pilot fuel jet from the jet block? I soak mine in carb cleaner for several minutes, blow dry with compressed air and then make sure I can blow through the jet using a small straw. Also, squirt carb cleaner in each float bowl orifice and make sure the cleaner exits somewhere.

Do the floats move freely and not binding?

 

[2maxowner]

The carbs were totally taken apart and every orifice and jet was cleaned. I even have cleaning tools that clean the jets very effectively, I've been a vistim of varnished up idle jets. The floats move freely. I removed the idle air mixture adjustment screws and blew those out as well. I have heard many times that these can be a bear to synch if they aren't set close to good after you rebuild the carbs. I tried to rig up a flow bench to try and get them at least flowing the same but i have had no luck with that yet, I need a larger vacuum source.
The problem with opening the butterflies more is the vacuum characteristics change when the fuel starts going through the off idle jets.

 

[maleko89]

Have you tried swapping carbs between your two bikes? Have you tested your compression?

 

[2maxowner]

The compression is good on both bikes. I was going to swap the carbs next...at this point, I'll try anything...