Topic: Making sure.. cb550 carbs

[Cvillechopper]

I just bought the 73 500 to 550 converted cb from Jeff that was listed in the For Sale section and need to make sure of one or two things.  First, I can't find the numbers on the carbs to make sure I have the right settings.  Anyone know where I should be looking?  On my 750K carbs the number's right on the side, plain as day.  Secondly, the carbs I'm used to dealing with have a fuel mixture screw, i.e. out = richer, in = leaner.  I think these carbs have an air screw, i.e. in = richer, out = leaner.  Is this right?  Just thought 'd check. 
I pulled the carbs and cleaned out some residue but didn't pull the air screws.  In one of the exploded diagrams I stumbled upon last night I saw that the air screw appears to have a passage at the end.  Is this right?  If so I can easily explain my idle issue and remedy it (hopefully).  Any way it goes, she's running and will be getting me to and from work once DMV opens tomorrow so there's another SOHC on the road in VA.

James

P.S.
Thanks again Jeff, she's in appreciative hands.

[TwoTired]

Year model makes a difference as the 77-78 CB550 carbs have different carb castings and slightly different adjustments than prior CB500/550carbs.

If you have the earlier carbs, I.D. numbers can be found on each carb body mount flange, top right.
0627B = CB500
022A = CB550K
069A = CB550F

These carbs have an air bleed pilot screw.  CC rotation leans the idle mixture.

There is a chart for settings in the Carb FAQ along with ID numbers fro the 77 and 78 CB550 Carbs.

I pulled the carbs and cleaned out some residue but didn't pull the air screws. In one of the exploded diagrams I stumbled upon last night I saw that the air screw appears to have a passage at the end. Is this right? If so I can easily explain my idle issue and remedy it (hopefully).
James

I'm not sure I understand the question.  The pilot screw meters air from the slow air jet and mouth of the carb to the chamber where the slow jet emulsion tube sits.  Cetainly a passagway exists for that purpose.

Cheers,

[Cvillechopper]

Sorry, I wasn't sure how to explain it.  On the diagram I saw there was a hole THROUGH the inner end on the adjustment screw.  Looked sorta like the emulsion tubes, but only one set of holes.  I've not noticed that on any carbs yet.  I'm thinking I was looking at the diagram cross-eyed or something. 
When you refer to the carb body mount flange, that's on side of the carbs facing the engine, correct?  I'll check when I get home this evening.

Thanks
James

[TwoTired]

Well, that's interesting.  And, I hadn't noticed that before.
The air bleed screw tips for the 627B and 022A carbs have hollow tapered tips and are indeed cross drilled.  This will limit the adjustment range of these screws and will not allow you to completely close off air flowing from the air jet to the pilot jet emulsion tubes. These tips have a 12 degree taper.

The 069A Carbs have a solid tapered tip, no holes, on the air bleed adjustment screws.  These have an 18 degree tapered tip.

Right and left side refer to orientation as you sit on the bike.
The carbs mount to a common interlinking flange.  The interlinking flange faces the engine.  The carb body flanges are behind and away from the engine.

Details...

[Cvillechopper]

OK, I've narrowed it down to either the 627B or 022A carbs as they do indeed have the crossdrilled air screw.  I still can't find a single number on the carb bodies, even with them on my bench using a flashlight to look in the little dark corners.  I did find that the needle was on the next to highest setting so I dropped it on notch to the middle on the first one I put back together, then realized I don't know where stock settings are.  My Clymer doesn't have it.  I'm off to FAQ to look for the setting and will try to get her on the road tomorrow if it's not still raining. 

I just realized that I didn't mention the exhaust set up.  It's a 4 into 2 set up that looks stock, but can't really tell.  Deffinately is baffled.  Oh yeh, I can't find the torque values for the exhaust nuts either.  Anyone know?  Some of the studs are a bit fragile as somewhere along the line 2 were broken and there was a nasty leak till I replaced them and snugged everything down.  I figure there's no use synching till I get that taken care of.

James

[Cvillechopper]

After attempting to synch the carbs with no luck (#4 cylinder was jumping all over the place) I took the carbs off again and double checked the float height on #4.  It was about 4mm off.  Everything back together and she fired right up, with a bit of popping while cold.  It was too late to leave her running for long so I'll get her warmed up today and see if she's any better. 

[dusterdude]

stays on her ass james