Topic: 1975 CB550

[Sswindle13]

Hello everyone! I just recently purchased a 1975 CB550 with 8000 original miles! It had sat for about a year and needed a good carb cleaning. I took apart the carbs and then rebuilt them. I then ran into some wiring issues so I rewired the whole thing and everything appeared to work pretty good. I started it up and and realized something was wrong with the Air/Fuel mixture it idles pretty rough and often dies and it will die every time I go to give it throttle. I don't really know what screws I have adjusted wrong and I can not find the factory screw settings anywhere. It has pods for the intakes and I might need to buy some different jets. I have the needles set 2 down from the top so they are dead center. I feel like even if the jets need to be sized up then it would at least be able rev? I'm pretty new to motorcycles but incredibly eager to learn and make this bike my next project but i'm at a loss for what to do, any help would be greatly appreciated

[denward17]

Welcome to the forum sswindle....good people here..

I'm not an expert but recently went through this on a '76 550K.

Air mixture screws out about 1 1/2 turns to begin with.  Try to use original Honda brass in the carbs if they came with them.

Not sure how many steps you have in your needle (mine had 5), but if you are in the 2nd from top, you might be too lean, especially with pods.

What do your spark plugs look like?

The bowl float level can also make a difference as well, Did you reset them to a particular height?

Did you look at the numbers on the main jet, idle jet and needle?  Have them available to talk about?

[bryanj]

They never run right with pods, you just have to put up with some carp at some point of throttle opening.
Mixture screws 1 1/2 turns out from a GENTLE searing all the way in, what exhaust do you have.
All the settings are in the genuine Honda manual

[Sswindle13]

Welcome to the forum sswindle....good people here..

I'm not an expert but recently went through this on a '76 550K.

Air mixture screws out about 1 1/2 turns to begin with.  Try to use original Honda brass in the carbs if they came with them.

Not sure how many steps you have in your needle (mine had 5), but if you are in the 2nd from top, you might be too lean, especially with pods.

What do your spark plugs look like?

The bowl float level can also make a difference as well, Did you reset them to a particular height?

Did you look at the numbers on the main jet, idle jet and needle?  Have them available to talk about?

I just changed all the spark plugs. My needle has 5 settings too, I'll go in and change the needle height today and see if that makes a difference. What setting do you recommend? I don't have the specs for the Jets and the needle but I'm 99% positive that they are stock. Ill probably end up switching back to the stock airbox if I can find one for a decent price, especially since i accidentally stepped on one of my pods today. I'm having a friend sync the carbs tomorrow and maybe that should help. I am almost certain its not getting enough fuel so. I also do not understand what people mean by "lightly seat" the Air/Fuel screws. I have an air screw and does "lightly seat" mean when I hear the spring in the screw depressing or when I feel the threads start to attach? The bowl float level is set to 22mm which is the recommended setting.

[Sswindle13]

They never run right with pods, you just have to put up with some carp at some point of throttle opening.
Mixture screws 1 1/2 turns out from a GENTLE searing all the way in, what exhaust do you have.
All the settings are in the genuine Honda manual

Ill post some pictures of my exhaust, I do not believe that it is stock but I'm not quite sure where it came from either. What do you mean by "Gentle searing" what should I be feeling for?

[carnivorous chicken]

Have you done the complete 3k mile tune-up, including points, timing, valves, etc? Carb sync too (and plugs and oil and filter change...). Does it run differently with choke?

Could be float height too, but usually a bit rare as it's tough for them to go out of adjustment.

[Sswindle13]

Have you done the complete 3k mile tune-up, including points, timing, valves, etc? Carb sync too (and plugs and oil and filter change...). Does it run differently with choke?

Could be float height too, but usually a bit rare as it's tough for them to go out of adjustment.

It has been completely tuned up, the only thing that hasn't been done yet is the Carb Sync which will be getting done tomorrow. It runs a lot better with the choke on so I can only imagine its not getting the right amount of fuel

[Nurse Julie]

Bryan meant 'gentle seating' ie, only screw the A/F screw in until you feel it touch, don't screw it in further.

[denward17]

Recommended notch for the needle is 4th from the top if I recall, especially with pods.

[Sswindle13]

Recommended notch for the needle is 4th from the top if I recall, especially with pods.

Thank you very much! I appreciate all the help!

[denward17]

If yours is a "F" model it could be different.

[bryanj]

The screw has a taper end which mates into a tapered seat, if you tighten too much you will deform both needle and seat in carb body and never get a good adjustment, so you must only gently screw in the adjusting screw till it VERY lightly touches

[Deltarider]

If yours is a "F" model it could be different.

This is reply #12 and we still don't know what model CB550 he has, 'F' or 'K'. The year doesn't give us a clue. This bizar US habit to inform us about a year... It's not meaningful at all. As far as airscrews it makes quite a difference if his bike has the 069A carbs or the 022A  (see overview attached).

[kerryb]

I have a ‘76 550f that came to me with pods.  After 3 months of trying many fixes, it would run well enough to ride it.  When I put the stock airbox system back on, it ran perfect because I had already been through the ignition and carb setups so many times.  The stuff that made the greatest difference for me was having the ignition timing spot on, and synching the carbs.  I have 069 carbs with stock jets (40 & 100?) and if I recall correctly, my mixture screws were open more than 1.5 turns.

[jlh3rd]

#38 and #98 jets stock for  '75, '76, & '77 550F's....069a carbs.

[kerryb]

#38 and #98 jets stock for  '75, '76, & '77 550F's....069a carbs.

Thank you for the correction.

[Stev-o]

They never run right with pods, you just have to put up with some carp at some point of throttle opening.
Mixture screws 1 1/2 turns out from a GENTLE searing all the way in, what exhaust do you have.
All the settings are in the genuine Honda manual

Ill post some pictures of my exhaust, I do not believe that it is stock but I'm not quite sure where it came from either.

Def not stock!  Does it have a baffle inside?  If no, it would be best to install one, they seem to like some back pressure.

Pull the plugs, post a pic and let us "read them".

[carnivorous chicken]

They never run right with pods, you just have to put up with some carp at some point of throttle opening.
Mixture screws 1 1/2 turns out from a GENTLE searing all the way in, what exhaust do you have.
All the settings are in the genuine Honda manual

Ill post some pictures of my exhaust, I do not believe that it is stock but I'm not quite sure where it came from either.

Def not stock!  Does it have a baffle inside?  If no, it would be best to install one, they seem to like some back pressure.

Pull the plugs, post a pic and let us "read them".

And no silencer (muffler). That should be a next step to getting it to run correctly.

[Duanob]

I'd start with a carb sync personally if all other specs are correct. Its amazing how bad they run when not synced and how smooth they purr when all synved up.

PODS = more air, 4 into 1 exhaust = less air. I have K model that came with PODs and. 4 into 1 and shorty muffler. I put 105 mains, 2nd needle position from the top, air screws 1 turn out. So far seems to rev and idle fine but still waiting for some other items before taking out on the street for a real test. BTW the 4 into 1 sounds fantastic!