Topic: 1977 CB550 SS Carbs

[glimpsedogg]

So i picked up a 1977 Honda CB550 Super Sport this weekend, it had been sitting for who knows how many years.  So it could use a good carb cleaning and rebuild, but the only carb kits that I'm finding say they are for 74-76 550s.  Will these carb kits work, sorry I'm new to the motorcycle world, I've looked some and haven't found if the 77 came with different carbs.  Here's a picture, please excuse the thrashed garage.  Thanks in advance

[TwoTired]

The CB550F model carbs are set up as 069a.  The carb castings are the same as any other F model 550, and K models from 74-76, as well as Cb500 carbs.
The carb set up is matched to the air filter type and exhaust.

I've never seen an upside down installation work, no matter which kit was installed.

Honda sells a "kit" that contains all the rubber/gaskets needed for a thorough cleaning.
After-market kits have most of the rubber plus other parts specific to the model (if you are lucky).
All the kits assume you will have stock components, and the aftermarket kits are cheaper, in part due to the lack of quality control on the metal part size tolerances.  This gives varying results with the final tune configuration.

If the internal metal parts are cleanable/uncorroded, they should still be functional.  If you are not going to use stock induction or exhaust, the extra parts may (or may not) help get the the bike running correctly when you need to change tuning parameters on the carbs.

Cheers,

[DaytonGuy]

TwoTired can correct me if I'm wrong here as he is the board's authority on the 550's....IMO.

I have a 77 550K model.  I have seen kits on the internet that are for the 77-78 550's.  They always seem to show a molded (or shaped) float bowl gasket (kinda square looking).  All of the kits I've seen for the earlier years only show a standard looking round bowl gasket (Keyster kits for example).  The 77-78 kits I've found (they are out there, but you have to look for them) were usually $40-$50 per carb...   The kits for the earlier models I have found have always been $12-$25 per carb.  I never really investigated any further to see if the earlier model kits would work.

I took my carbs apart and all of the internal metal bits were dirty, but still seemed usable after cleaning.  I did not replace my float bowl gaskets, but the carbs are still on my work bench and the bike in what seems like a million pieces so I don't know if they will leak.  You can replace the float valve (I think that's what it's called) for $2-$4 each. 

Anyway....now you have my $.02.

Chris

[TwoTired]

The 77-78 Cb550K models had PD style carbs ("PD" molded into the carb body).  The 75-77 Cb550F models used the earlier style castings.  That's how US models were, anyway.

Cheers,

[OldSchool_IsCool]

TwoTired can correct me if I'm wrong here as he is the board's authority on the 550's....IMO.

I have a 77 550K model.  I have seen kits on the internet that are for the 77-78 550's.  They always seem to show a molded (or shaped) float bowl gasket (kinda square looking).  All of the kits I've seen for the earlier years only show a standard looking round bowl gasket (Keyster kits for example).  The 77-78 kits I've found (they are out there, but you have to look for them) were usually $40-$50 per carb...   The kits for the earlier models I have found have always been $12-$25 per carb.  I never really investigated any further to see if the earlier model kits would work.

I took my carbs apart and all of the internal metal bits were dirty, but still seemed usable after cleaning.  I did not replace my float bowl gaskets, but the carbs are still on my work bench and the bike in what seems like a million pieces so I don't know if they will leak.  You can replace the float valve (I think that's what it's called) for $2-$4 each. 

Anyway....now you have my $.02.

Chris

DG,

+1000 on TT's 550 cred!

As for the molded aftermarket bowl gaskets, I have been fighting bowl overflow issues on my '77 550 "PD" carbs for a week now.  I eventually took my aftermarket bowl O-Rings off and the bowls no longer overflow.  Leak like hell if the carbs tip, but don't overflow.  I have OEM o-rings on the way and can report later if they fix the overflow AND leak issue. 

I still cant figure out the geometry of the aftermarket O-rings that cause the overflow.  Must be interference with the float rise is all I can figure.

[glimpsedogg]

thanks for all the info, this forum is a gold mine of information.  You guys really know your stuff.  The bike was last registered in 2000 so i'm guessing it has been sitting since then.  Here's a couple pictures i took tonight.

[TwoTired]

Whoops!  Those are the PD carbs! Not the ones that belong to a bona fide 77 Cb550F.
Better check the Vin number.  Either you have the wrong carbs, or someone has grafted parts from a real super sport onto a K bike.

Best find out now, the manifolds are different for the two carb styles.  You also need the bar mounted choke knob for those PD carbs.  I don't see one in the pic you posted.

Also, the kick start lever and right flip up foot peg/brake lever are a set that works together on the 550F frame. (If that's what you have.)

Anyway, the carbs you have are for the 77-78 K style.  Should have a PD46 number on them.

Here's what a 77 CB550F should look like.  The windshield, crash bars, tail rack and rest aren't stock.  The rest is.

Cheers,

[glimpsedogg]

So looks like I have the wrong carbs on there, would it be best to try to source some different carbs from an actual 550f or just stick with the pd carbs i have?

[NickC]

Someone may correct me, but that looks like you have a CB550K engine, according to the serial number........

[TwoTired]

Yes, that is a 78 K motor in an F model frame.  Could be they changed the entire engine along with the carbs.  That would mean the intake manifold is correct for your carbs. 
Have you checked for carb fit/ alignment?
The carbs you have look restore-able, btw.
Do you have the bar mounted choke knob?  You'll need one for those carbs.
What are your plans for air filter?
Did the bike ever run with these carbs?  I think the throttle cables are different for the two carb styles.

There is no difference in the 78 K or F motors aside from intake and exhaust bits.

You could, for example, find the proper carbs along with the intake manifold and carb couplers, etc.  And, it will work fine that way.  But, I don't know what goals you have for the bike.  I suppose it depends on what parts surrounding the carbs that you have the most of.

Your going to need F model foot pegs, brake lever, and kick start lever, too.

Cheers,

[DaytonGuy]

Aside from the 77 - 78 F vs K thing you have going on there....I agree that the carbs look salvageable.  I have those carbs on my bike and they were actually dirtier than those.  Unless you removed it, you are missing a main jet in the right carb in the upper photo.  You need to remove the main jets and the main jet holder and clean out all of the passages.  I used copper wire from an old speaker wire,  Some of those holes are pretty small.  You will also need to remove the pressed in jet which is located just under the main jet  holder (tube in the center of the carb) in your photos.  This thing is a press fit so you need to grab it with a pair of pliers and put firm, but not to firm pressure and pull it out.  Once clean, you can tap it back.  That hole is really tiny so find some small wire and don't assume it is clean until you can get the wire to pass all the way through.

Here's a picture...



1 - The float valve is uner there.  You will see it once you remove the float.
2 - Main jet holder.  The main jet screws into the top of this
3 - Pressed in Jet or Slow Jet
4 - Air mixture screw

When I got my bike I thought I had an SS because someone had put an SS tank on it.  The title and frame both say K...

[glimpsedogg]

I'm going to start cleaning the carbs out tomorrow, i had the one disassembled to get a better look.  Things are making a lot more sense now that I know the motor and carbs are 78s and dont match the f frame.  I probably should have done some more research before i bought the bike, I was wondering why the kick start was not compatible with the foot peg or brake.  Apparently the bike did run with those carbs before it was parked, but that was around 2000.  It also had pod filters on it when i bought it.

[OldSchool_IsCool]

Something important, make sure the parts you take out go back into the carb body from where it came.  Bag 'em and tag 'em!

[glimpsedogg]

so i've cleaned out the jets and bowls now, but i haven't had much luck finding how to adjust the floats on the k carbs anyone have any tips

[DaytonGuy]

Holding the carb as shown in the pic above, the height of the float should be 14.5 mm measured from the carb body to the top of the float.  You'll need to bend the tab (the thing #1 is pointing to) of the float that rests against the float valve to adjust the height.

[BigKat]

Hey there, first post. I just bought a 77 Cb550 and im currently refurbishing the carbs. Question about O-rings... I found only one O ring after removing all the jets from the float bowl. Pictured is where I found it. Am I missing rings or am I just confused? Thanks!

[TwoTired]

The 77 cb550f supersport used the older style carbs with set up 069a.
O rings for the main jet, float valve seat, bowl gasket and the t couplers between carbs.

The cb550k model had PD style carbs with far less orings. Idle mixture screw, bowl gasket are the same only two, I can think of right now. Probably for the carb fuel rail couplers, also.

Cheers,

[BomberMann650]

Ugh what is it with the cafe racers and all the upside down parts!
Upside down forks, upside down rear brake, upside down handlebars, and now carburetors too?!
Gimme a break!

[Lostboy Steve]

TwoTired can correct me if I'm wrong here as he is the board's authority on the 550's....IMO.

I have a 77 550K model.  I have seen kits on the internet that are for the 77-78 550's.  They always seem to show a molded (or shaped) float bowl gasket (kinda square looking).  All of the kits I've seen for the earlier years only show a standard looking round bowl gasket (Keyster kits for example).  The 77-78 kits I've found (they are out there, but you have to look for them) were usually $40-$50 per carb...   The kits for the earlier models I have found have always been $12-$25 per carb.  I never really investigated any further to see if the earlier model kits would work.

I took my carbs apart and all of the internal metal bits were dirty, but still seemed usable after cleaning.  I did not replace my float bowl gaskets, but the carbs are still on my work bench and the bike in what seems like a million pieces so I don't know if they will leak.  You can replace the float valve (I think that's what it's called) for $2-$4 each. 

Anyway....now you have my $.02.

Chris

DG,

+1000 on TT's 550 cred!

As for the molded aftermarket bowl gaskets, I have been fighting bowl overflow issues on my '77 550 "PD" carbs for a week now.  I eventually took my aftermarket bowl O-Rings off and the bowls no longer overflow.  Leak like hell if the carbs tip, but don't overflow.  I have OEM o-rings on the way and can report later if they fix the overflow AND leak issue. 

I still cant figure out the geometry of the aftermarket O-rings that cause the overflow.  Must be interference with the float rise is all I can figure.

I had these problems. I used a dab of permatex fuel resistant sealer on my fingers and coated my aftermarket orings with it. It's a thin blue stuff. I am no longer having these issues.

Sent from my LG-H931 using Tapatalk

[Bankerdanny]

I just use tiny dabs of Permatex at the corners of the bowls, and I mean tiny, you don't want any excess to squeeze out into the bowl where it could vibrate off and block a jet. It holds the gasket in place and if you ever decide to replace the gasket comes right out of the groove with a toothpick.