HeLP!

+1. If you're in this "for the long haul" (or have multiple multi-cylinder bikes) it's a worthwhile investment for sure. Plus you don't even need to completely remove the gas tank if you're just checking or making minor tweaks.

 

Sorry should have read the whole thread prior to my last response...

Cylinders are numbered 1-4 from left-right when seated on the bike.

"open for the tank vacuum" not while trying to sync, right? You're on "PRI" beacause the CarbTune is hooked up to all 4 manifolds, correct?
Check to be sure the vacuum nipple itself isn't loose in the manifold if that's the pot the petcock line hooks up to.

 

My bike is so far out of tune now I'm having a difficult time getting it back into sync. The idle seems to change (possibly due to the out of sync issue) jumping from 3000rpms to below 1000.

The numbers in the photo are reversed. It's cylinder #2 that is really out of sync. The #2 port is hooked up to the sync tubing during the sync. It's on PRI. Vacuum nipple is not loose (that I can tell, any way). I'm going to recheck the manifold side of the intake and see if something is loose.

I tried riding the bike to work last night and it handled so poorly, I only got about a half mile before I turned around and came back. Poor throttle response in 1st, seemed to be ok in second, albeit slow response on the throttle, but downshifting caused the bike to drop to below 500rpms. Started right back up, but difficult to "rev up". Choke caused the bike to rev to over 3500rpms.

I'm happy that it's running at least, but this is almost worse than it not running because I'm so close but no cigar.

Thanks for the reclarification on the cylinders. I kind of knew that, but the carbs being numbered backwards threw me for a loop.

 

You might need to simply step back, take a deep breath; and pull the carbs off again.

Be 110% sure all 4 slides pass the "clunk test" with flying colors.

Check your float levels using the "clear tube method."

Do a very careful bench sync and be sure the idle stop screw allows the butterflies to close COMPLETELY. All of them.

Smear a dab of silicone grease around the inside lip of the manifolds before you reinstall the carbs; be sure they all get seated properly in their manifolds.

Fire it up and check for air leaks again before reattaching the carbtune.

 

Passed the clunk test.
Bench synched prior to reinstall

Has anyone ever done the float test while carbs on bike? Anyone? Show of hands please. No? Crap.

Will give your suggestions a try.

 

The photo of the Meter shows you have NO Manifold Vacuum on the Line 2nd from the Left.
The Manifold Vacuum is LOW because there is "Something" preventing that Hole from drawing a Vacuum --> Between the Throttle Plate and the Combustion Chamber.

Throttle Shaft Seals
Throttle Butterfly Open far more than others.
Intake Manifold Not Clamped Securely
Intake Manifold Cracked or Split -- (Sometimes requires probing)
Cracked Rubber Manifold to Head Base
Manifold NOT AIR TIGHT to Cylinder Head
<><><><>
Cylinder NOT Drawing Vacuum
Burned Valve (Test Compression)
Tight Valve (Test Compression Wet Test)
Bad Rings (Test Compresstion -- Dry/Wet)
<><><><>
Major Mechanical
Stuck Valves
Scored Cylinder Wall
Piston Crown Cracked
Piston Crown Holed
Cylinder Head Gasket Blown
(Compression Checks: Dry / Wet )
(Blowby Test)

Get the Values of a Compression Test ASAP.

 

Wouldn't an air leak explain his idle issues as well?

 

Yes.
Of course.
An AIR Leak!

At any of the sources I listed.
I'm sorry for not being more specific.