Topic: CB550 - What carbs are these?

[Gregory Groth]

From poking around the forums, I gather that I should be able to determine what carbs I have based off of numbers stamped on the side of the carbs.  Unfortunately, I can't seem to find any.  The bike in question is a 1978 CB550, but it's somewhat of a frankenbike.  When I attempted a rebuild of the carbs some 5 years ago, I ended up buying rebuild kits for a '76 from my local honda dealer based off of the fiche, so I'm assuming these carbs aren't original.  My engine rebuild is coming to a close, and I want to start gathering info for the upcoming carb rebuild (float level, jet sizes, etc).  Pictures attached so someone can hopefully point out something I overlooked.

[Gregory Groth]

More pics

[the technological J]

i dunno about them but here are the stock PD style

[dave500]

yours are type one carbs,the id is on the mounting flange as shown here,make sure they are all the same,ive had the odd one out on a rack before,check all the jets are the same aswell i also had a mix of them in that same rack.

[Gregory Groth]

Thanks a ton, every post I've read on this subject seemed to indicate that the part numbers were on the flange just above the bowl, like in the pics from technological J.  Between failing vision, poor lighting & corroded aluminum, I couldn't see the part numbers until I knew where to look 

Now I can tell I have a rack of 022A's.  Does anyone know if there will be any issues getting these to work on a '78 engine?  I do know that I will need to get a set of older intake manifolds as outlined here: http://forums.sohc4.net/index.php?topic=85743.  Any other issues I should be aware of?

[Fritz]

I don't see any problems with using these carbs on a 78 model.

Maybe you should confirm the jet and needle sizes:
http://www.sohc4.com/wp-content/uploads/2009/04/550carbid.jpg

[Deltarider]

I don't see any problems with using these carbs on a 78 model.

Neither do I. Differences, if any, were minute. Stock K3's with their PDcarbs were set a bit too lean. My guess is driveability might improve with the oldstyle carbs. Just find the right way to couple.

[dave500]

i like the type ones better,theyll run fine,use the standard jetting they have and when you ride it then see if any jetting changes need to be made,,,are you running the stock airbox?

[TwoTired]

Now I can tell I have a rack of 022A's.  Does anyone know if there will be any issues getting these to work on a '78 engine? ....
 Any other issues I should be aware of?

The carbs will work.  Jetting/setup depends on the exhaust choice, providing you use a stock air box.

Both the front and rear carb couplers are different. (shorter for the PD carbs)  And you need the early carb manifolds to get vacuum ports for syncing, and match the carb spacing difference between models,

You will lose the choke knob/cable, and the throttle cables are different, as well.  and, it will still be a "frankenbike". 

Cheers,

[Gregory Groth]

First off, thanks for all the replies, I wouldn't have made it this far without this forum.  The exhaust is 4 to 1 off a CB550F, and is Honda OEM (the Honda part number is visible on the muffler).  The bike came with pods, but I am planning on putting a stock airbox back on it.  I do have most of the pieces for one, but the box where the filter goes seems to be shorter than the one on there now (the only piece left from the original).  It also doesn't have any ports on the bottom for the crankcase breather (the original has 2).  From looking at everything I have, I plan on using the 022A's.  I already bought some intake manifolds with the necesarry vacuum ports (should be here in a week).  Hooking up the airbox I have that's missing the ports on the bottom.  Getting a Uni air filter.  Running the crankcase breather to a tube, and run it to the same spot as my carb overflows, unless of course I should be doing something else.

The frankenbike stuff doesn't end there either.  The original seat was toast when I got it, and the seat pan was rotted through.  I have one off of a '76 on there now.  The side covers, I think are original (painted black).  The gas tank is badly faded and is either brown or maroonish?  (i'm color blind, and have trouble with shades of red).  I'm focusing all my time, energy & money on just getting it up and running dependably.  I don't know if I ever will attempt to restore it to 1978 specs.  To me all the chrome & the spoked wheels in an age of crotch rockets is enough to keep me happy.

[TwoTired]

The only Honda CB500/550 filter boxes that didn't have the crankcase breather were from the Cb500s.  Why can't you use the one on there now?  Why not use the engine breather?

The F model's 4 into 1 had 069A carbs with different jetting than the 022A.  (See, the carb FAQ)  It'll run with the 022a set up.  But expect poor fuel economy as it will run too rich.

I'm surprised putting the F's 4 into one on a K bike would allow the brake arm and kick lever to operate properly.

Cheers,

[Gregory Groth]

The only Honda CB500/550 filter boxes that didn't have the crankcase breather were from the Cb500s.  Why can't you use the one on there now?  Why not use the engine breather?

The F model's 4 into 1 had 069A carbs with different jetting than the 022A.  (See, the carb FAQ)  It'll run with the 022a set up.  But expect poor fuel economy as it will run too rich.

I'm surprised putting the F's 4 into one on a K bike would allow the brake arm and kick lever to operate properly.

Cheers,

It's quite possible the airbox I have is from a CB500, I bought it off of Ebay some 5-6 years ago.  My only reason for using it would be I wouldn't need to hunt down the internals that are needed for proper venting of the crankcase that sit under the air cleaner.  Unfortunately there's no motorcycle boneyards in the immediate vicinity of Chicago, so Ebay ends up being my main alternative.

If I indeed do have a 550F exhaust, in your opinion, would I be better off sourcing a set of 069As or rejetting the 022As?

I have added a couple pictures that show the exhaust setup that I inherited.  The muffler clearly states that it's a 550F part, I have no clue if the header is a Honda item or not, I'm not familiar enough with the 550F to say.  Perhaps I have a Honda muffler attached to an aftermarket header?  Perhaps I have even more frankenbike parts than I realized?

[Fritz]

Hi,
 
 yes, your muffler and headers are indeed of a 550F 4-1
 
 TT is right: You'll need the foot pegs, foot break lever and kick starter arm of a 550F or modify the ones that you have in order to make them work with this exhaust system.
 
 Cheers
 Carsten
 
 
 
 

[TwoTired]

I would put in the newer air filter box.  You could plug those bottom holes until you sourced the internal parts.  There are enough bike modifiers here, that those internal parts will eventually come up for sale or give away.   Put an ad in the want ads.  The parts for completion would just be drop in, when they arrive.

The exhaust system is definitely Honda stock for the Cb550 F model.  (4 O steel wool should make those shine nicely.) To run it's best, 069a carb would be ideal.  As you could just assure they were at factory settings and drive blissfully away.  The 022A will run, but require tweaking.  I'm not sure where you'd get #98 mains.  I've not adapted 022a carbs to the F exhaust.  With #100 main, I expect the plug to soot at high throttle settings, even with the slide needles dropped down to the 2nd position.  The 069a also used different air bleed screws, and I have not fully investigated repercussions of this.  Kinda depend if you are a carb tuning savant, or want to add setting up carbs to you knowledge base.  Go a test track? access to a Dyno?

Does the brake arm hit the exhaust?  Does the foot pedal flip up to allow kick start operation?  I'm not sure how the F foot peg will adapt to the 77K frame.

[Gregory Groth]

I would put in the newer air filter box.  You could plug those bottom holes until you sourced the internal parts.  There are enough bike modifiers here, that those internal parts will eventually come up for sale or give away.   Put an ad in the want ads.  The parts for completion would just be drop in, when they arrive.

The exhaust system is definitely Honda stock for the Cb550 F model.  (4 O steel wool should make those shine nicely.) To run it's best, 069a carb would be ideal.  As you could just assure they were at factory settings and drive blissfully away.  The 022A will run, but require tweaking.  I'm not sure where you'd get #98 mains.  I've not adapted 022a carbs to the F exhaust.  With #100 main, I expect the plug to soot at high throttle settings, even with the slide needles dropped down to the 2nd position.  The 069a also used different air bleed screws, and I have not fully investigated repercussions of this.  Kinda depend if you are a carb tuning savant, or want to add setting up carbs to you knowledge base.  Go a test track? access to a Dyno?

Does the brake arm hit the exhaust?  Does the foot pedal flip up to allow kick start operation?  I'm not sure how the F foot peg will adapt to the 77K frame.

I'll leave the original airbox in then.  I'm guessing that my rear tire would be happier for it, if I can find somewhere else to go with the crankcase vapor.

Test track, no.  Dyno, no.  I don't mind fiddling with carbs, but since this would be my first attempt at a quad setup, I think I'll chicken out and see about getting a set of 069As.  From tearing down the engine, the pistons were loaded with carbon, as were the valves, so I can assume that the PO had issues with it running rich as well.

The brake arm doesn't hit the exhaust, so I'm guessing that the PO "modified" (aka "bent") it so that it wouldn't hit.  To be honest, I never tried the kickstart, and will have to wait until the engine is back in the frame to do so.

Many thanks to all that have replied.