The International CBX Owners Association

Trust me when I say I feel your pain !!
My experience was very similar to yours, after I had 'done' my carbs and was trying to dial them in.
Bench synching, by setting the plates using idle orifices as references , was less than a success for me. Using 1mm. surgical wire, I would slip it under the plates & then move the adjusters just enough to allow it to pass. Trouble was ( I later determined) the wire was raising, slight, ridges on the plates and putting scratches on the carb floors, as it passed. Even if I was mindful of how much pressure was being placed on it. Both errors stopped the plates from closing completely. The plates came out, again,the imperfections were addressed and I tried another method. It solved my issues: As the carbs were still off, I pulled the slides out, and backed the idle adjuster completely off ( now is a great time to verify your fast idle adjustment too). Starting with #4 and working out to #6, I placed a bright light source ( a Luxeon flashlight) at the carb throat. The individual synch adjusters got backed out enough to allow their throttle plates to close irrespective of their neighbors. Throttle plate retaining screws were loosened & their plates 'snapped' closed a number of times (gently, but firmly) to make absolutely certain, they were perfectly aligned in their bores.... no light was getting past. The screws got another, light, application of Loctite blue. Manipulate the idle adjust screw so that the #4 plate is just closed. Working out to #6, set the adjusters so that the plates are all just closed. Similarly, work out from #3 to #1 & repeat the same proceedure. After all the plates were set in this manner, when the idle adjust screw is moved to open the throttles, all the plates can be seen to be opening at the exact same time( they all allow the light to just pass). You can make slight adjustments with the synch. adjusters at this time. Conversely at this point,with the idle ajuster completely out, no throttle plate should be seen to be allowing any light to pass. Button the carbs back up, slap them back in, and do a proper synch., That's what did it for me
From my experience, and as many others on the board have mentioned, there are no half measures when doing CBX carbs. 'Good enough' won't fly. I have never worked on a motor that is more sensitive to carb set-up!
I sure hope this is heplful

got3 snow,

Yes I think that is it. There is a air passage from the top to the bottom. On the topside they look like ig holes but one of them is the size of a wire brush bristle. I had 2 of them plugged on a set of carbs and I didn't catch that one till the 3rd. time I pulled them. If it was mine I would check that for sure. I do feel your pain. You will win in the end if you have enough time.

I need to see a photo (close-up) of your 'perfect' bench sync. I still think you are pretty far off if you can't close off the bleed holes by backing the #4 adjuster completely off. And for a correct adle speed just the SLIGHTEST bit of the first bleed hole gets exposed, not the complete hole. Also note - as much as you have fiddled with the adjusters, they are not very robust. You can easily strip the holes and bend the adjusting arms - then you're in real trouble. You really need to get a handle on EXACTLY what you are doing before something really bad happens. PM me if you want.

Dave

The photo I posted dipicts the bleed holes of #4 showing when I put it on the bench last night to "bench sync". I thought that was my problem so I took a photo to share. I then adjusted them all starting with #4. I had to back off others first to allow #4 to close. All were adjusted to the point that the first bleed hole was just starting to show. I started with 4 then proceeded to do 5,6 and then 3,2,1. In the end the first bleed hole was barely showing in all. I snapped the plates open a few times and was satisfied they were adjusted as described. I have since installed them so I can't get a photo this time around.

I snapped the plates open a few times and was satisfied they were adjusted as described. I have since installed them so I can't get a photo this time around.

I liked using the 'light' method because, afterward,I was certain that the plates were seated across the bores. Before that I had used more conventional methods to seat them, and thought ( because I had done tons of carbs similarly) that they were good to go. About the millionth ( no exaggeration ) time that they were off, the light showed how wrong I was. Even if they hang open a,seemingly,insignificant amount, that will be enough to create the symptoms you are experiencing. An absolute baseline has to be that when the idle adjuster is backed off, there is no possibility of air finding its way past any of the throttle plates. You cannot correct for this,after the fact, with the synchro adjusters.

Well, As much as I hate to take them off again, I guess I will have to. I adjusted them so you can barely see the first bleed open. But, they are open compared to your method. I can't believe that with such a small throttle opening the engine will race to 5000 rpm's. But, you are correct, they are not completely closed and I can't close them completely as adjusted.. Is there any possibility the slides can be opening?

Actually, from what I understand the symptoms to be, the slides might not be a significant factor. Being CV carbs, the slides only react to the throttle plate movement. At idle, you can lift the slides with your finger, the mixture might get a bit richer, but the idle won't increase.
If, on the other hand (as happened in my case) , the throttle plate(s) cannot be closed fully with the idle screw backed out, the idle speed might be ok on a cold motor ( almost synch-worthy in fact). As the motor warms, and fuel atomization becomes less an issue, you'll find the idle climbs on its own, and can't be corrected with the idle speed knob or synching. The,small, amount of air passing the,unseated, plates is keeping the idle too high.
I'm no expert, but from my, humble, observations during my time in carb-hell, that was the issue. Once the plates were adjusted to fully block the bores, normal synching ( ya right, on a SIX) got her goin'.

Success Finally!
It's alive and well. Another five hours work and finally idling correctly. It sounds so good and responsive, but I haven't rode it as it was wet,rainy and dark. So I am not totally out of the woods.

OK, so in the end I took off the carbs again,(third time this week), benched sync'ed them, and worked to get the plates as perfectly closed as possible (using a light). And adjusted them so the fast idle could close them all completely, yet when I turned the fast idle adjustment out all carbs would begin to show the first hole in sync.. Synced them as described in prior posts here. Started with 4 then 5,6, 3,2,1. Bottom line, I wanted to make sure the throttle plates could be completely closed and sync'ed which seemed to contribute to my problem. I know that may not be clear, but it was a pain..


I am not planning on doing any more adjustment with my vacuum gauges. I hope this is not a mistake?

Mike Nixon should add syncing the carbs or someone else should write a how to book as that is such a critical part of rebuilding the carbs so I have found..

Thank you all for your support.. Pictures to follow..!!!!

Good man, way to go.

N.

I agree. Nixon's carb book is a good one but it is missing a few things to give us a complete successful job. I guess that "complete book" would be at least 2" thick. Would be alot of info put on paper. The "carb book" is an excellent resource to get you started.

OMG I am in Heaven! When you do a complete restoration the rewards are so great. This bike is such a dream. I have to go ride! Thank you all for your support and patients! Chip
And that is camera flash on the tail, not a chip in the paint!!

Very glad it finally came together for you, as you can see with members like Dave, Mike and the others if you are determined enough to keep at it they are just as determined to help you get it right.

If you don't have much clutch rattle and all your cylinders have the same compression readings within 10 percent I guess you can skip the final sync but wouldn't you like to know how close you really are after all the work you have done?

All the cylinders pull different amounts of vacuum due to the unequal intake runner lengths, each cylinder's condition and how well the valves are seating so having them all set the same may not be optimum.

Maybe take a break, enjoy the bike for awhile and come back and check the sync down the road a bit.

Enjoy your CBX.

Your bike looks great. Thanks for keeping us posted on your project. There is nothing like success !!
Nows it's time to enjoy your ride!!!

It's always nice to see an original looking CBX coming back together again! Why does the bike have a km/h speedometer?

What a great feeling, eh? ( nod to the Canuk members that ).
I think we're talking a Single Malt moment here!
Bask in the glow,baby, bask in the glow.
Go team!
Oh, and yer bike looks the business !