Carb Sync Issues - Part 2
 

Work has had me out of town the past three weeks - finally got back to getting the bike back into shape.

1st - tried to bring carb #2 & 3 together using a vacuum gauge. #2 was showing about 15" of vacuum - #3 was around 5". I couldn't get any real response from adjusting the screw. I eventually ended up pulling the rack again - wanted to be sure I had at least a reasonable bench synch to start from. This time I noticed that the #3 & #4 carbs appear to move simultaneously, slightly before #1 & #2. And, when released, it appears that #3 & #4 do not close quite as far as do #1 & #2. I can't find any way to adjust out this difference.

Carbs 1&2 appear to be"synched" - and my earlier efforts seem to confirm this - and 3&4 appear to be moving together - it is the "difference" between the two banks that has me stumped.

Any ideas/suggestions?

Could it be possible that the adjustment screw between #1, #2 and #3, #4 is stripped or not engaging correctly?

Near as I can tell, all of the adjustment screws are working well. I can match #1 and #2, and #3 and #4 - what I can't do is sync the two pairs.

With the rack off the bike and the idle speed adjustment backed all the way off, the #3 and #4 carbs are open slightly more then the #1 and #2 pair - and that-s with thier adjustment screws backed all the way out. It looks like the common linkage from the throttle cable drum to the two banks is out of whack - but I don't see any way to adjust this. There are two arms - one for each pair - that are linked by pivots and bushings, with no obvious adjustment.

One other observation - the adjustment screws for #1 and #4 are in very close to the same "plane" at rest. #3 is noticeably above this plane, with no obvious way to cfhange its orientation. The adjustment screws ride in "brackets" that are "keyed" to the throttle shafts - they are only going to attach in one orientation.

It's got me puzzled!

Could it be possible that this bank of carbs were fully disassembled by yourself or worse yet a previous owner?
I disassembled mine completely for a complete cleaning, and it took me a few attempts of reassembly to get everything working correctly.

^ +1

I bought the bike a couple of years ago with right at 12,000 miles on it. While the guy I bought it from was not the original owner, it was nearly pristine and no evidence of it having been mechanically molested. I did split the two outer carbs from the rack to replace the fuel T o-rings, but the two center carbs were not disturbed - and this is where the "problem" appears to be. I have a second carb rack I picked up cheap for spares - and it too has this "offset" assembly between the #2 & #3 carbs, so I don't think this is incorrect - but I'm not claining it isn't. I'm hoping the collective wisdom of this group can shed some light on what is correct and how to go about bringing the two pairs into better agreement.

If I were you I would break them apart and check everything at this point. Linkages are misaligned somewhere. Sorry, I haven't been of much help!

When I can't figure out an issue on a bike I have a tendency to tear it all apart and start from scratch. That way I can control every step of reassembly and I assume nothing!

I would tend to agree - but for the life of me, I can't see how the linkage joining the two pairs of carbs can go together any other way. The "adjustment plates" have oblong slots that engage the throttle shafts in only two possible orientations - and the other possibility would not allow any access to adjustment and probably wouldn't clear the carb bodies. I don't see any sort of adjustment on the joining arms - they are fixed length links that transfer the motion from the throttle cable drum to the two banks and are attached to their ends by small c clips. I can see how to remove them, but not how to make any sort of a change.

This bike shows no signs of having been worked on by previous owners - and the fact that my "spare" carb rack looks exactly the same makes me pretty confident this is assembled correctly - it is getting that second pair of carbs to close down slightly that has me baffled.

You sure all the little 3/8 inch springs are in there ? makes no sense the butterflies
are not closing back with tension

Springs and adjusting screws are in place. Butterflies close as far as they can. It appears that the linkage joining the two pairs of carbs is where the "disconnect" is and for the life of me, I can't see how to change their relationship