1978 CB550 clueless and curious

Y

yoyo

Guest
A couple weeks ago I picked up this 1978 cb550 for $600. The bike shows just over 7,000 miles on it. I am pretty inexperienced in this kind of thing and am just kind of learning as I go. I had a couple small engine classes in high school but that was a while ago now. The bike is not running but certainly sounds like it wants to get up and go. After trying to get the bike to start I started tearing the bike down. I was planning on cleaning the carburetor but after fiddling with that for a while I found one of the sections had been corroded beyond repair. I found another set of carbs off a 1978 cb550k nearby for $100. I went out grabbed it and brought it home to find it was a different version than the one I have. I have been looking around for the past week trying to find out what the main differences between these two are and how I will put the new ones onto the bike. It appears the new carbs are the PD 46C carbs. Any help would be much appreciate! I have been looking through these forums and havent been able to find much, if you know of anywhere I can find more info just post a link and I'll read through it until I know what to do. Thank you!
 

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I don't know the differences between the banks of carbs, but if the new set is complete clean them up and slap them on and see what happens.

How's the compression on the cylinders? Also before you bother trying to start the engine, make sure the timing and valves are adjusted.

These are super easy to do and you don't need the bike to be running to do them. They don't change once the bike is up and running, and you need to do these first.

And go to this post I put up a few years back and download yourself a nice PDF copy of the original Honda Service Manual :)

http://www.dotheton.com/forum/index.php?topic=20071
 
Oh and you're sure that's a 1978 model? I thought by then the CB550K had started using the 'F' tank with the flip cover over the gas cap.

My first bikes were a 1973 CB500K and a 1976 CB550F. Still among my fave all time bikes. You can rebuild the engine without removing it from the frame, which is more rare than you'd imagine.
 
Tim said:
I don't know the differences between the banks of carbs, but if the new set is complete clean them up and slap them on and see what happens.

How's the compression on the cylinders? Also before you bother trying to start the engine, make sure the timing and valves are adjusted.

These are super easy to do and you don't need the bike to be running to do them. They don't change once the bike is up and running, and you need to do these first.

And go to this post I put up a few years back and download yourself a nice PDF copy of the original Honda Service Manual :)

http://www.dotheton.com/forum/index.php?topic=20071
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Thank you sir! I will be doing a lot of reading and tinkering tonight when I get home from work. The frame says its a cb550k but the side plat has the 550f on it.. I also have read that the 550K comes with the 4 to 4 exhaust on it
 
If you have more time than money I have saved far worse than those carburettors .
CLR for the calcium like deposits
soak in trans fluid and lacquer thinner for a few days
soda blast what you can .
clear all passages any way you can

it can be done

~kop
 
kopcicle said:
If you have more time than money I have saved far worse than those carburettors .
CLR for the calcium like deposits
soak in trans fluid and lacquer thinner for a few days
soda blast what you can .
clear all passages any way you can

it can be done

~kop
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That far right one was far too corroded. That cast iron middle piece that comes up and holds a brass/copper piece was so corroded it sat flat on it and not within it like the others. It was about a quarter inch shorter than the other carbs. I'll post a picture when i get home, it was definitely too far gone haha
 
blackbuddha1 said:
CLEAN THE TANK!
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I'm assuming you're referring to the inside of the tank? I read a little bit about doing that but I don't know what to do with the gas that was left in it haha
 
yoyo said:
That far right one was far too corroded. That cast iron middle piece that comes up and holds a brass/copper piece was so corroded it sat flat on it and not within it like the others. It was about a quarter inch shorter than the other carbs. I'll post a picture when i get home, it was definitely too far gone haha
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that trans fluid to thinner is %50/%50

kop
 
Like Tim asked, are you sure it's a 78? I believe they went from the 022 carbs (like mine, 75', and your fugly ones) to the PD's in 76, maybe 77.
 
Check the compression, check that there's a spark, clean the tank (inside), clean the carbs that you want to mount on the bike, adjust the valves, adjust ignition, charge the battery. Should get her running.
 
canyoncarver said:
Like Tim asked, are you sure it's a 78? I believe they went from the 022 carbs (like mine, 75', and your fugly ones) to the PD's in 76, maybe 77.
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This is what the frame is telling me
 

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78 it is. Wonder if somebody switched them out. Either set will work. I'd go with the later PD's. I would advise sticking with the stock airbox for awhile instead of doing pods. Just sayin.
 
canyoncarver said:
78 it is. Wonder if somebody switched them out. Either set will work. I'd go with the later PD's. I would advise sticking with the stock airbox for awhile instead of doing pods. Just sayin.
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I've heard a lot of people saying that so I might stick with the air box until I have more money, time and knowledge to put pods on. I was looking at these http://forums.sohc4.net/index.php?topic=79491.0
The Anti-Pod.

I placed the carbs back in the bike to see how it lined up with the other carbs and it looks like the new ones are slightly wider. I hope this wont affect anything.
 
I'd say then that someone has taken the tank and sidecovers off a 1974 CB550K (Sunrise Orange metal flake I think) and put them on yours. A massive improvement in my opinion.

Anyhow - like I say, clean up the bank of carbs, do the timing and valve lash and press forward. A compression test is worthwhile (remove all plugs to ensure you identify if the head gasket is blown between any cylinders) to see how things look in general - but adjust the valves first.

Valves
Compression test
Timing (static test light method)
Carbs

In that order. Clean the gas tank if it needs it - inline fuel filters too.

Is all the electrical in working order? Check all the fuses etc. Don't take any more apart though!
 
That's the correct side cover for the K model. Honda put 550 Four on the side of all the CB550's. The seat you've got there is aftermarket. By the way, if those original carbs were mine, I'd use them. All that white stuff is NOT corrosion. It's a fuel additive, and lots of it. I would take the carb off the mounting rail and boil it in a pot of water with a couple of cups of vinegar in it. I swear it'll clean up like new. However, if you're convinced they're garbage, I'll take them off your hands for the cost of shipping! Pm me.
 
yoyo said:
I've heard a lot of people saying that so I might stick with the air box until I have more money, time and knowledge to put pods on. I was looking at these http://forums.sohc4.net/index.php?topic=79491.0
The Anti-Pod.

I placed the carbs back in the bike to see how it lined up with the other carbs and it looks like the new ones are slightly wider. I hope this wont affect anything.
Click to expand...


I've seen that thread for awhile, I think they've stopped selling them. Stick with your airbox and go through the list Tim posted.


Do you want to ride it or rebuild it?
 
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