Topic: Syncing the 78' 550K

[Tews19]

SO the 550K is running like a champ... Only took forever and I was told today the reason I couldn't sync was due to me trying to use #2 to go off of. I was told that to sync properly, the idle sync carb is #4.. Is this true?? Funny when I was told this becasue I was able to get 1,2,3 synced but never number 4... then when I would get a ready on 4, the rest would lower and the bike would die... ANyways, just was looking for some input as I didnt see this in the manual and I thought I saw the manual saw to go off of #2 as it is set to factory and can not be adjusted

[Danno]

I believe your friend could be correct use 4 as a baseline and go the other way see how it turns out

[TwoTired]

SO the 550K is running like a champ... Only took forever and I was told today the reason I couldn't sync was due to me trying to use #2 to go off of. I was told that to sync properly, the idle sync carb is #4.. Is this true??

Not if you have "PD" molded into the carb sides.
Did you look under the top of cover of #2 Carb?  Do you see an adjuster there?

I suppose it is possible to dismantle and rearrange the adjusters, so that another carb becomes the reference carb.  But, the factory didn't do that.

[Tews19]

See i thought that too... NUmber 2 can not be messed with at all and you always go with that... I don't know anymore.. this is confusing.. Damn government rules back then to lean the bikes out..............

As far as PD molded into the slides, I am not sure.. I do not remember..

All I know is that by going off of 4, the bike idles perfect at 1k and I have a lot more power..

[TwoTired]

All I know is that by going off of 4, the bike idles perfect at 1k and I have a lot more power..

So, how did you adjust 2 so it matched 4?

[Tews19]

I have no freaking clue.. Thats why I made the thread. They guy who did it stated he used four as the baseline to idle.... Is he full of it? I tried for several days to sync and clean and i could not get it to run well. Had a guy look at it and thas what he said he did andits running great... Any reason for concern here or things that may possibly fail later?

[bryanj]

Basically if it runs good it is good

[TwoTired]

Is he full of it?

Well ...yes,  if your carbs are PDs and in factory configuration.

Any reason for concern here or things that may possibly fail later?

If you are happy with the way it runs, and all the pipes are equally hot, then just enjoy the bike.

[Tews19]

Is he full of it?

Well ...yes,  if your carbs are PDs and in factory configuration.

Any reason for concern here or things that may possibly fail later?

If you are happy with the way it runs, and all the pipes are equally hot, then just enjoy the bike.

Thanks TT. Just to be clear, #2 carb is to go off of when sycning correct? And there is no such thing as a idle carb to use, hence #4?

[TwoTired]

To be clear...
  In stock form, the 78 CB550k with PD carbs has no capability to adjust individual slide height on the #2 carb.  Therefore, it MUST become the master to which all other carbs are adjusted to, with respect to vacuum sync procedure.
Each carb is otherwise independent and none is designated to dominate the idle speed in and of itself.  Syncing is what makes them all work together to drive a common crankshaft.

When they are maladjusted, any of the individual carbs may dominate or skew idle speed.  But, even if one example were to be found, it does NOT prove that all similar maladjusted examples will also demand #4 is dominant.  There is nothing inherent in the design to make that so.

If you encounter a CB550 with NON-PD carbs, ALL the carbs in the bank 1 though 4 have individual slide height adjusters.   You can declare any of the 4 carbs to be master and adjust others to it.  It is also possible to skew all the slides in the bank such that they physically can't fully close.  Then, even if they are all in perfect vacuum sync, the idle cannot attain low or 1000 RPM speed.

[Danno]

sorry to confuse you was not meaning to
 now that two tired said it I remember he is exactly right