Topic: 1978 CB550 Carb Diagram

[BomberMann650]

...and emission standards/changes with the carb years.

Were there certain years that outperformed the others because of these subtle changes?

[calj737]

...and emission standards/changes with the carb years.

Were there certain years that outperformed the others because of these subtle changes?

Very argumentative answer.

[Scott S]

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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 If you have a '77, factory setting is 2 turns from lightly seated. The '78 used 1.5 turns. You have pods so be prepared to experiment.
 On the PD carbs those screws are on the engine side so they control fuel. The more you turn them out, the more fuel...Richer... You'll get.

[BomberMann650]

...and emission standards/changes with the carb years.

Were there certain years that outperformed the others because of these subtle changes?

Very argumentative answer.

Oh i didn't want to start an argument    seemed a prudent question given how many of us like to mod these engine setups.
I don't posess the theorhetical knowledge to appreciate the effect of different degree profiles of needle jets 

[Jkstull]

...and emission standards/changes with the carb years.

Were there certain years that outperformed the others because of these subtle changes?

Very argumentative answer.

Oh i didn't want to start an argument    seemed a prudent question given how many of us like to mod these engine setups.
I don't posess the theorhetical knowledge to appreciate the effect of different degree profiles of needle jets 

I think he meant some people would say yes to your original question, and others would say no. Meaning we don't really know. Lol.

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[Jkstull]

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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 If you have a '77, factory setting is 2 turns from lightly seated. The '78 used 1.5 turns. You have pods so be prepared to experiment.
 On the PD carbs those screws are on the engine side so they control fuel. The more you turn them out, the more fuel...Richer... You'll get.

Okay. This thread is starting to give me a real good understanding of my machine. Big thanks to everyone with the patience to stick around. Is all of this laid out in the links provided? I haven't had time to do much research on said links. Unfortunately work gets in the way of that.

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[calj737]

I think he meant some people would say yes to your original question, and others would say no. Meaning we don't really know. Lol.

Exactly. Kind of like arguing over what the best electronic ignition is. Everyone has their favorite-

Theoretically, the earlier year carbs would run better given their lack of EPA intervention on exhaust emissions. Also, the earlier year carbs can be tuned more easily, and across a wider range. So in effect, one should be able to extract more horsepower from the engine. But this is all subjective and I have no evidence from side-by-side Dynos runs for multiple year bikes in equal condition with stock systems.

And all of this is superseded by the fact that everyone knows Flake Sunrise Orange bikes are fastest. And Planet Blue Metallic the slowest- 

[BomberMann650]

I think he meant some people would say yes to your original question, and others would say no. Meaning we don't really know. Lol.

Exactly. Kind of like arguing over what the best electronic ignition is. Everyone has their favorite-

Theoretically, the earlier year carbs would run better given their lack of EPA intervention on exhaust emissions. Also, the earlier year carbs can be tuned more easily, and across a wider range. So in effect, one should be able to extract more horsepower from the engine. But this is all subjective and I have no evidence from side-by-side Dynos runs for multiple year bikes in equal condition with stock systems.

And all of this is superseded by the fact that everyone knows Flake Sunrise Orange bikes are fastest. And Planet Blue Metallic the slowest- 

You're trying to tell me those traffic cone lookin supersports are faster than me and my friend bloo?!?! 

Its candy sapphire blue too.  Like a stripper 

[Jkstull]

Okay. I've been looking for a match on the screws for my choke linkage. I'm coming up short, and I've emailed harisuluv and haven't gotten anything back. The manuals show part numbers for the screws on a 1977 K4, but not a 78. Can anyone help me out? The 78 seems to be off the grid in many ways...

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[Scott S]

 What's the part # for the '77?

[Fezzler]

Okay. I've been looking for a match on the screws for my choke linkage. I'm coming up short, and I've emailed harisuluv and haven't gotten anything back. The manuals show part numbers for the screws on a 1977 K4, but not a 78. Can anyone help me out? The 78 seems to be off the grid in many ways...

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True?  I'm about to buy a 1978 CB550 Four K4.  Are they different and unique and under documented?

[harisuluv]

i have all the screws.  you need the 8 screws for the butterflies?

[BomberMann650]

Okay. I've been looking for a match on the screws for my choke linkage. I'm coming up short, and I've emailed harisuluv and haven't gotten anything back. The manuals show part numbers for the screws on a 1977 K4, but not a 78. Can anyone help me out? The 78 seems to be off the grid in many ways...

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True?  I'm about to buy a 1978 CB550 Four K4.  Are they different and unique and under documented?

From what I've seen, the 78 k bikes underwent a few cosmetic changes.  Seat, sidecovers, and the tank looks like they put decals on a supersport F tank.  They kept the popular 4into4 pipes and pd carbs.

The model guide;
http://www.sohc4.net/cb550-model-guide/

[Jkstull]

i have all the screws.  you need the 8 screws for the butterflies?

Yes I do! I messaged you earlier. I can't find them anywhere else.

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[Deltarider]

Were there certain years that outperformed the others because of these subtle changes?

As a matter of fact: yes. The CB550F and the CB550F1 performed best. Although the CB550F2 had the same 069A carbs, Honda must have changed something. The German press complained about less driveability in comparison with previous models and showed that also the older CB500K2 (G) that had been tested in 1976, perfomed better (see pic. below*). Must have something to do with the new regulations I guess. Remember that the CB550F2 was on the market in the same period as the CB550K3 with even leaner PD carbs, so probably the setting was somewhat adjusted. The only thing I've found is that some carb scheme's show an advised airscrew opening that went from 1¹/₂ (CB550F and CB550F1) to 1³/₄ (CB550F2) but I don't know if that was the cause and if not there were other things.
* 'Beschleunigung' means acceleration and 'Höchstgeschwindigkeit' means topspeed. Source: Motorrad 18/1977.

[BomberMann650]

I was really impressed by those zero to 60 times, then i realized it was kilometer scale haha!

[Jkstull]

i have all the screws.  you need the 8 screws for the butterflies?

Hey harisuluv, did you want to work something out for those screws?

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