Author Topic: 1978 CB550 Carb Diagram  (Read 14003 times)

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Offline Fezzler

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Re: 1978 CB550 Carb Diagram
« Reply #25 on: January 03, 2017, 07:36:03 PM »
I've de-racked carbs.
It was a necessary evil.

Okay, newbie here.  Define "de-racked" please.  I'm sure it doesn't mean don't take them off the bike to clean.  It most probably means do not completely disassemble.  I also am about to buy a 78 CB550F K4 with the PD carbs.  To be clear, I see a lot of information about cleaning, replacing jets and pins and other parts, BUT I am also seeing some very knowledgeable mechanics/enthusiasts here saying "clean the hell out of them but don't take them about and risk damaging or losing the soft bass components."

Set me straight.  Thanks.
1975 Honda CB550f in parts in progress
1978 Honda CB550 Four K4
1971 Honda CB500 Four K0
2008 105th Anniversary Edition HD Road King
(Sold) 1998 Honda Shadow ACE Deluxe VT750
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Offline Fezzler

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Re: 1978 CB550 Carb Diagram
« Reply #26 on: January 03, 2017, 07:39:02 PM »
I've de-racked carbs.
It was a necessary evil.
It was kind of fun putting them back together, but I'm afraid I missed out on something. Won't know until after I get the rest of the bike together though.

Unfortunately there are too many well-intending motorcycle owners who begin disassembling their bikes with utterly no regard for inventory organization.


Well this brings up a question I was going to ask.  Once one decides which parts of the bike need disassembly and repair, what I the best procedure for keeping parts in tact?  I have read photo graph disassembly.  I imaging plastic bags or containers that can be labeled are good?  Perhaps group by schematics?

One particular basketcase i entertained buying had been literally disassembled with a hammer.  😓
It is ridiculous, what I've seen. My buddy disassembled his, after I told him not to do so. Now I am afraid to help because I don't know a thing about the bike.

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1975 Honda CB550f in parts in progress
1978 Honda CB550 Four K4
1971 Honda CB500 Four K0
2008 105th Anniversary Edition HD Road King
(Sold) 1998 Honda Shadow ACE Deluxe VT750
1973 Schwinn Stingray (Blue Deluxe - RIP Jack and Rose)

Offline Jkstull

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Re: 1978 CB550 Carb Diagram
« Reply #27 on: January 03, 2017, 07:43:04 PM »
I've de-racked carbs.
It was a necessary evil.

Okay, newbie here.  Define "de-racked" please.  I'm sure it doesn't mean don't take them off the bike to clean.  It most probably means do not completely disassemble.  I also am about to buy a 78 CB550F K4 with the PD carbs.  To be clear, I see a lot of information about cleaning, replacing jets and pins and other parts, BUT I am also seeing some very knowledgeable mechanics/enthusiasts here saying "clean the hell out of them but don't take them about and risk damaging or losing the soft bass components."

Set me straight.  Thanks.
Deracking means to separate the carbs into 4 separate carburetors. Completely disassembling. It is not necessary in all circumstances. It is a pain to get back together, and you can replace needles, gaskets and most o-rings without doing so.

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Offline Jkstull

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Re: 1978 CB550 Carb Diagram
« Reply #28 on: January 03, 2017, 08:37:51 PM »
Another thing I want to post here, according to the 3rd link in the glorious comment mentioned above holding a lot of information, these carbs slide mounts have 2 different kinds in the PD46C model. Carb number 2 being the one that is supposed to be the odd one out. (I have no idea why, but it is supposed to be the only non-adjustable slide mount.)

Here I have it pictured incorrectly.



And correctly here.



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Offline BomberMann650

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Re: 1978 CB550 Carb Diagram
« Reply #29 on: January 03, 2017, 09:02:41 PM »
Nice helmet Fezzler - and yes Jkstull beat me to it.

These 550/4 carburetors live attached to a solid chunk of aluminum we call "the rack".  Add a latin prefix, and you've got four carb bodies that are no longer fixed to said rack. 

As for organizing your hoard of disassembled bits n bobs.  Keeping mechanisms in one piece is preferred.  But in my case, I have completely stripped two sets of A series carbs down to the bodies and tucked the core components into these nifty little hardware boxes I get at Ace for $14/set.  One big box, one small box...so far I've filled 8 of these containers with carb pieces, top end pieces, engine hardware, and a few odds and ends of spares as I needed to hide them.

I have shamelessly begun the process of cannibalizing cb550 stuff for my own....future needs.  The one bank of carburetors was in pretty sad shape, rust and corrosion on what should have been shiny parts.  And somehow, the rack itself was bent on the one set (pictured below).  Assumably damaged in the same crash that broke the engines lower case mount.  So apart they came to be cleaned, sorted, and eventually refurbished into one bank of really tits carburetors....eventually.

This sort of megalomania is really an individual preference.  I bagged the smallest, most lost prone pieces, and labeled the bags before tucking them into a compartment.  Some of the throttle linkages remained together, because they had even more lose-able parts inside.  I did what made sense to me.  And hopefully did a well enough job that, should i die or be put in a position that i become a "previous owner" myself - the next guy isn't gonna be posting about the idiot who put a cb550 into a tackle box...or ten.

Offline Jkstull

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Re: 1978 CB550 Carb Diagram
« Reply #30 on: January 03, 2017, 09:10:58 PM »
Nice helmet Fezzler - and yes Jkstull beat me to it.

These 550/4 carburetors live attached to a solid chunk of aluminum we call "the rack".  Add a latin prefix, and you've got four carb bodies that are no longer fixed to said rack. 

As for organizing your hoard of disassembled bits n bobs.  Keeping mechanisms in one piece is preferred.  But in my case, I have completely stripped two sets of A series carbs down to the bodies and tucked the core components into these nifty little hardware boxes I get at Ace for $14/set.  One big box, one small box...so far I've filled 8 of these containers with carb pieces, top end pieces, engine hardware, and a few odds and ends of spares as I needed to hide them.

I have shamelessly begun the process of cannibalizing cb550 stuff for my own....future needs.  The one bank of carburetors was in pretty sad shape, rust and corrosion on what should have been shiny parts.  And somehow, the rack itself was bent on the one set (pictured below).  Assumably damaged in the same crash that broke the engines lower case mount.  So apart they came to be cleaned, sorted, and eventually refurbished into one bank of really tits carburetors....eventually.

This sort of megalomania is really an individual preference.  I bagged the smallest, most lost prone pieces, and labeled the bags before tucking them into a compartment.  Some of the throttle linkages remained together, because they had even more lose-able parts inside.  I did what made sense to me.  And hopefully did a well enough job that, should i die or be put in a position that i become a "previous owner" myself - the next guy isn't gonna be posting about the idiot who put a cb550 into a tackle box...or ten.
Wow. That crash must've been pretty bad to Crack the engine AND bend a carb rack. You aren't looking to share the wealth of CB550 Carb parts you own are you? Having trouble finding the screws that attach the choke flaps to their mounting positions. (Forgive me for my ignorant knowledge on the correct terminology of said choke flaps.)



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Offline Jkstull

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Re: 1978 CB550 Carb Diagram
« Reply #31 on: January 03, 2017, 09:11:46 PM »
I don't know why my photos are being posted in a rotated fashion. Sorry guys.

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Offline BomberMann650

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Re: 1978 CB550 Carb Diagram
« Reply #32 on: January 03, 2017, 10:07:23 PM »
PD carbs?
I happen to have a (not perfect but fixable) set of 46A's.  PM me.

Offline Deltarider

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Re: 1978 CB550 Carb Diagram
« Reply #33 on: January 03, 2017, 11:42:25 PM »
Quote
Another thing I want to post here, according to the 3rd link in the glorious comment mentioned above holding a lot of information, these carbs slide mounts have 2 different kinds in the PD46C model. Carb number 2 being the one that is supposed to be the odd one out. (I have no idea why, but it is supposed to be the only non-adjustable slide mount.)
When Honda mounted the PD carbs on newer models CB550, #2 was supposed to be the non-adjustable slide mount. This to avoid chasing your tail when you are trying to synchronize the carbs. On the old-style carbs found on previous models all were adjustable.
« Last Edit: January 03, 2017, 11:52:46 PM by Deltarider »
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Offline Deltarider

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Re: 1978 CB550 Carb Diagram
« Reply #34 on: January 04, 2017, 01:41:32 AM »
Quote
Wasn't it this site where somebody posted a lot of pics showing his disassembly/assembly of your type of carbs? Unfortunately the 'search' is still down,
I think I've found it. http://forums.sohc4.net/index.php?topic=146893.0 Allthough these are CB750 carbs you may find pics usefull whenever you're in doubt.
« Last Edit: January 04, 2017, 03:19:59 AM by Deltarider »
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Offline Jkstull

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Re: 1978 CB550 Carb Diagram
« Reply #35 on: January 04, 2017, 06:35:27 AM »
Quote
Wasn't it this site where somebody posted a lot of pics showing his disassembly/assembly of your type of carbs? Unfortunately the 'search' is still down,
I think I've found it. http://forums.sohc4.net/index.php?topic=146893.0 Allthough these are CB750 carbs you may find pics usefull whenever you're in doubt.
Those are PD42A carbs, where mine are PD46C. They resemble each other but aren't quite the same. They also have great info I didn't mention, or know about. Thanks Deltarider!

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Offline Jkstull

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Re: 1978 CB550 Carb Diagram
« Reply #36 on: January 04, 2017, 09:22:59 AM »
Might be a dumb question answered elsewhere, but what are these brass needles for? I replaced them, do they need adjusted a certain way?

The forum isn't allowing me to post photos. They are a needle on each carb outside of the float bowls, with a spring, washer and o-ring. On the side that goes towards the engine.

Should I note any other screws that might need adjusted? I'm asking for myself and others who may not know.

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Offline BomberMann650

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Re: 1978 CB550 Carb Diagram
« Reply #37 on: January 04, 2017, 09:43:11 AM »
Might be a dumb question answered elsewhere, but what are these brass needles for? I replaced them, do they need adjusted a certain way?

The forum isn't allowing me to post photos. They are a needle on each carb outside of the float bowls, with a spring, washer and o-ring. On the side that goes towards the engine.

Should I note any other screws that might need adjusted? I'm asking for myself and others who may not know.

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On the bottom of the carb towards the intakes?  I was told those are the idle air/fuel mix screws, and there should be a small metal tab fixed to each of them.

Offline Scott S

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Re: 1978 CB550 Carb Diagram
« Reply #38 on: January 04, 2017, 10:10:45 AM »
 If you're talking about the needles in the slides, they control air/fuel mixture. Their biggest effect is around mid range, but they effect it everywhere to some degree. Yes, it matters how they are installed; what clip position they're in. Also, be sure the cut outs on the slides are facing the proper direction. And bench sync the carbs once they're all back together.
 You say you replaced them...I hope you re-used the stock brass. Aftermarket brass is often (read: almost always) the wrong size or profile. Clean and re-use the Keihin parts.

 The tab on the mixture screws underneath is there to limit the range of adjustment. I don't remember tabs on the 550 carbs, but do on the 650 carbs. It was an EPA thing to keep them lean. You can grind them off to get more adjustment.
 The mixture screws on the 550 PD series carbs are very hard to adjust on the bike, You need a small, short, thin blade screw driver....and you WILL burn your hand!

Some useful PD links:

http://forums.sohc4.net/index.php?topic=124332.0

http://forums.sohc4.net/index.php?topic=98867.0
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Offline Fezzler

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Re: 1978 CB550 Carb Diagram
« Reply #39 on: January 04, 2017, 10:18:02 AM »
That looks great and makes sense.  I was wondering to myself, it would be cool to have a black and white printing of the artist "blow out" sketch of the components and check, mark that all are present and throw that in the box or bag too.  I've watch many videos where guys buy parts and it's all there but one bolt or some clip etc.
1975 Honda CB550f in parts in progress
1978 Honda CB550 Four K4
1971 Honda CB500 Four K0
2008 105th Anniversary Edition HD Road King
(Sold) 1998 Honda Shadow ACE Deluxe VT750
1973 Schwinn Stingray (Blue Deluxe - RIP Jack and Rose)

Offline Jkstull

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Re: 1978 CB550 Carb Diagram
« Reply #40 on: January 04, 2017, 10:26:17 AM »
If you're talking about the needles in the slides, they control air/fuel mixture. Their biggest effect is around mid range, but they effect it everywhere to some degree. Yes, it matters how they are installed; what clip position they're in. Also, be sure the cut outs on the slides are facing the proper direction. And bench sync the carbs once they're all back together.
 You say you replaced them...I hope you re-used the stock brass. Aftermarket brass is often (read: almost always) the wrong size or profile. Clean and re-use the Keihin parts.

 The tab on the mixture screws underneath is there to limit the range of adjustment. I don't remember tabs on the 550 carbs, but do on the 650 carbs. It was an EPA thing to keep them lean. You can grind them off to get more adjustment.
 The mixture screws on the 550 PD series carbs are very hard to adjust on the bike, You need a small, short, thin blade screw driver....and you WILL burn your hand!

Some useful PD links:

http://forums.sohc4.net/index.php?topic=124332.0

http://forums.sohc4.net/index.php?topic=98867.0
Scott, those links really help. Thanks. I replaced the needles, main, emulsion and air/fuel ratio screw with a kit from 4into1. I'm assuming I should undo all my work, and use the stock brass?

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Offline Jkstull

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Re: 1978 CB550 Carb Diagram
« Reply #41 on: January 04, 2017, 10:30:30 AM »
I'm also going to be running pods and a 4 into 1 exhaust. Should I run this rich or lean? Starting with the needles, I have the eclips on the second from the top. Should I drop the clip raising the needle creating a richer mixture?

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« Last Edit: January 04, 2017, 01:47:09 PM by Jkstull »

Offline Jkstull

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Re: 1978 CB550 Carb Diagram
« Reply #42 on: January 04, 2017, 10:41:25 AM »
I know tuning will be a necessity. I'm just trying to get a good jump on it.

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Offline calj737

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Re: 1978 CB550 Carb Diagram
« Reply #43 on: January 04, 2017, 11:14:10 AM »
"Normally" pods will want to see a bump in the Main jet, plus a needle clip change. Moving the needle clip down physically on the needle increases the fuel (raises the needle). If you want to take a SWAG at it now, raise the needle 1 notch from stock location. Then, you can later adjust your jets (doesn't require removal of carbs from bikes in all situations).

But tuning, tuning and more tuning is headed your way.  :)
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'73 500 Build http://forums.sohc4.net/index.php?topic=132935.0

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Offline Deltarider

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Re: 1978 CB550 Carb Diagram
« Reply #44 on: January 04, 2017, 11:49:13 AM »
But you mean these, right? They're for the idle mixture. I'd leave everything standard.
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« Last Edit: January 18, 2017, 07:32:30 AM by Deltarider »
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Offline BomberMann650

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Re: 1978 CB550 Carb Diagram
« Reply #45 on: January 04, 2017, 12:30:23 PM »
I have a question about slide needle profiles.
When i was doing my homework - I noticed honda used different needle profiles on different years/makes/submodel of 550.  To what effect I wonder?  I do not know how to rationalize all of the numbers.




Offline Deltarider

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Re: 1978 CB550 Carb Diagram
« Reply #46 on: January 04, 2017, 12:51:12 PM »
Quote
I have a question about slide needle profiles.
When i was doing my homework - I noticed honda used different needle profiles on different years/makes/submodel of 550.  To what effect I wonder?  I do not know how to rationalize all of the numbers.
The difference was between K and F models, so had to do with either 4-4 or 4-1 exhaust.
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Offline calj737

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Re: 1978 CB550 Carb Diagram
« Reply #47 on: January 04, 2017, 01:43:34 PM »
...and emission standards/changes with the carb years.
'74 550 Build http://forums.sohc4.net/index.php?topic=126401.0
'73 500 Build http://forums.sohc4.net/index.php?topic=132935.0

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Offline Jkstull

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Re: 1978 CB550 Carb Diagram
« Reply #48 on: January 04, 2017, 01:48:32 PM »
But you mean these, right? They're for the idle mixture. I'd leave everything standard.
Yes, that is the needle I was talking about. Not the needle in the slide. Is there a certain depth that should be at?

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« Last Edit: January 04, 2017, 01:55:04 PM by Jkstull »

Offline BomberMann650

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Re: 1978 CB550 Carb Diagram
« Reply #49 on: January 04, 2017, 01:53:38 PM »
Quote
I have a question about slide needle profiles.
When i was doing my homework - I noticed honda used different needle profiles on different years/makes/submodel of 550.  To what effect I wonder?  I do not know how to rationalize all of the numbers.
The difference was between K and F models, so had to do with either 4-4 or 4-1 exhaust.

Oh right the pipes!!!  Duh!  I'm a cow