Topic: '76 CB 550 - I have carb questions... long and could be boring.

[Deltarider]

Like here. BTW, radcb550, didn't you promise to scan and mail that manual? This forum is all about helping each other.

[radcb550]

If your local Honda dealer has stock then yes, jets are a maybe but best to see if you need them first. If they are 98 main jets for instance I have some spare I think, may also have some 38 idle jets as well. Genuine jets, not copies. I also have some emulsion tubes if required.

If needed I can also supply some new felt washers that are fitted to the slide lifter shafts, 4 of those, and the choke shafts use them as well, another 7 there. Those were never available separately and only came with a new carb body. I suspect your carb were flooded with water after the petrol dried up and it’s my feeling that’s the green stuff left after that also dried up. Like stagnant water with the green tinge. If that’s so I’d suggest inspecting the alloy inside the float bowl area closely as water can seriously corrode this type of alloy, especially that main jet tube.

Have you found the carb identification number yet? Should be stamped on the right hand side of the mounting flange where the carb bolts to the mounting bracket

Man, that is great to hear that you may have spares.   I need to find time to even remove the bank of carbs so I can discern just what I need.

I did find the carb ID number...  thanks.

Rob

Like here. BTW, radcb550, didn't you promise to scan and mail that manual? This forum is all about helping each other.

Indeed, this is a wonderful group for information, everyone is so helpful and that is appreciated.  Refreshing in this day...

I did promise to scan the manual and I know that I have been delinquent.  We are in the throes of a fairly significant home project, and I can only steal away for a few minutes at a time in the evenings to work on the CB...

I will scan the first page or two and get them off to you for review.

Thanks,
Rob

[HondaMan]

Funny, Honda overdid things however, because now - looking at the picture - there are no less than 4 O-rings for the T-joint in each set.

This isn't the first time! They did this same sort of thing with the 750 and the 350 twins, many times. It got pretty bad for a while during 1990-2006 for some reason, then went flat wrong for many 750 parts. It started getting better after some of us wrote to them in 2010, reminding them of Sochiro's promise to us.

[Deltarider]

It's still a mystery why Honda has stamped the CB550K2 carbs 087A and not 022A like the CB550K(0) and the CB550K1 had. In the parts list by American (!) Honda*, the only clue would be in p. C10 where at #7 we find a different airscrew listed for the K2, the same solid one the F models had and not the hollow and cross drilled ones that were on the CB550K(0) and CB550K1. However... so far all owners of a CB550K2 I have asked, reported their CB550K2 had the open crossdrilled airscrew fitted and not the 16016-390-004 the parts list suggests. But... then there's no difference between the 022A and the 087A carbs, unless maybe the jet needles had been positioned other than in the 4th position from top.
* https://www.honda4fun.com/dwnload/Part-List/CB550/CB550-K0-K1-K2-Parts-List.pdf

[denward17]

My 087A needle was/is in the 4th position from top........and is running a little rich on low end right now.

[bryanj]

4th from top lifts the needle so more fuel gets through so richer

[Deltarider]

My 087A needle was/is in the 4th position from top........and is running a little rich on low end right now.

Yeah, but that doesn't automatically imply it was originally in 4th... Seen in time, I mean nearing tighter rules on emissions, one would rather expect the opposite.

[Oddjob]

Actually the opposite is more likely, as the emissions laws bit the manufacturers had to run them leaner and leaner to pass the new laws, this meant flat spots and the way the owner got rid of those was to make the mixture richer. Same is still true to this day.

[bryanj]

From memory Honda did not play the lean burn game till the 550K3 with PD(devil) carbs

[Oddjob]

California started to cut emissions back in the late 60s. By 1976 all engines burning petrol were required to meet certain standards, this was broadcast ahead of time and manufacturers were already trying to produce engines that went some way to meet these standards, hence why the 550f has smaller jets and bigger air bleeds than the 500 and stuff like the breather recycling system. The 550k3 was a model that honda thought could survive longer but ultimately it failed as it was a poor compromise between performance and looks. It wasn’t really well received by the public.

[scottly]

The major shift in emissions came in 1972, and affected all 50 states, but California had the strictest rules. Luckily, these rules did not apply to motorcycles.

[Deltarider]

Only a relatively 'new' CB550K2, not being tampered with, could be a reliable source to find out the truth. Could. On the other hand... American Honda documents are not the most reliable in my experience. That's why I have had to make several notes in the overview below. 

[Deltarider]

My 087A needle was/is in the 4th position from top........and is running a little rich on low end right now.

Denward, I have re-edited reply #28 and I apologise for the confusion that might have risen.

[HondaMan]

From memory Honda did not play the lean burn game till the 550K3 with PD(devil) carbs

In the 750 it started with the F2/K7 bikes. The F3 can be tricky to tune if it is the California version with the PD42/b carbs: cold-blooded as a vampire...

[Duanob]

My review on the 4 into 1 carb kits:  The gaskets and o-rings so far are good. I love the bowl gaskets, they just fit perfect. I hated the round ones, it was an act of futility sometimes to get the bowls on with the orings in place, no matter what I tried. I didn't use the pilot or main jets, I bought those at JetsRus. Since my project came with PODs I went with bigger jets, 40 pilots and 105 mains. I did put the float jets from the 4 into 1 kit in since the old ones had worn out jet springs and leaked. So far the 4 into 1 float jets are working. I seemed to be able to set the float height easier with new jets. That's all I got so far. Good luck.

[Oddjob]

Are the bowl gaskets shaped? They used to come from Honda like that but now they just supply round ones.

[HondaMan]

On the other hand... American Honda documents are not the most reliable in my experience.

Boy, you can say THAT again...

Did the 087a have the taller idle-mix screw heads that [once] held the little plastic turns-limiter caps on them? The 750 086a carbs were like that, but not otherwise different from the 7A or the 657b 1-fuel-line versions.

[Deltarider]

[...] Did the 087a have the taller idle-mix screw heads that [once] held the little plastic turns-limiter caps on them? [...]

As the information stands now, the 087A carbs are identical to the also oldstyle 022A carbs. So far nobody has been able to indicate any differences. So far no owner has reported the solid tip airscrews mentioned in the parts list*. All owners had the open end cross drilled air screws in the 087A carbs on their CB550K2s, the same screws found in the 022A, 627B and 649A carbs. Turns-limiter caps are not in the parts list, nor have they been reported. I believe they were on the later PD carbs. It seems American Honda has messed up. I also mistrust the info they gave on the settings of the 627B carbs (CB500) in that spec booklet edited by them in 1977. I made a special note on that in the overview below.
* in p. C10 at #7 https://www.honda4fun.com/dwnload/Part-List/CB550/CB550-K0-K1-K2-Parts-List.pdf

[Duanob]

Are the bowl gaskets shaped? They used to come from Honda like that but now they just supply round ones.

Yep, they are shaped.