Topic: 78 550K Carb cleaning help needed

[ugmold]

Hi Folks,
1st post. I just picked up a 78 550K in decent shape and while cleaning the carbs I found the info in my Clymers did not match. They are cleaning up ok, but appears the slo jets which had to be pulled out with pliers, are all clogged up. Any remedies to clear? Also my floats, plastic, are unlike the ones in the manual so I don't think the 22mm setting they specify will be right?

Any help is greatly appreciated.



thanks ugmold

[OldSchool_IsCool]

Welcome to the insanity Ugmold!

There is an FAQ section on this site that has a really good write-up on general carb cleaning.  You can also find on-line copies of various Honda shop manuals.  Yes, the Clymers and the Haynes manuals didn't update their carb sections when Honda changed carb models on the '77 & '78 550's.

[ugmold]

Thanks found a different setting of 12.5 for the float in the FAQs. But I went to ridenow.com and found what I think is what I am referring to as the "slo jet", they call it the (#7) screwset A , but the pic is tiny, and it looks in 3 parts, where mine, as seen in the pic here is 1 pc.



I don't think I'm going to find specific info about the "slo-jets" clogged, or maybe they are supposed to be solid in the middle? I can't see thru them, or blow air thru them.

Thanks for reading,
ugmold

[Gordon]

The slow jets, also known as idle jets, are one piece.  You should be able to see light through them.  If not, soak them in a cleaning agent and blow them out with compressed air, and spray aerosol carb cleaner in the carb passages followed by compressed air, too.  Do this at least three times while you have everything apart.  It's no fun to pull the carbs multiple times to do the same thing over and over again.

[OldSchool_IsCool]

Take great care not to change the sizes of the holes!

[kevio]

I don't mean to hijack your thread but I was curious what you plan to do about new gaskets and O-rings.  I also have a 78' 550k and haven't had any luck finding rebuild kits.

[TwoTired]

Thanks found a different setting of 12.5 for the float in the FAQs. But I went to ridenow.com and found what I think is what I am referring to as the "slo jet", they call it the (#7) screwset A , but the pic is tiny, and it looks in 3 parts, where mine, as seen in the pic here is 1 pc.

#7 is the Idle Mixture Screw.  The slow jet isn't shown in the diagram because Honda did not offer replacement jets.  You have to buy the whole carb body assembly to get those, as Honda did notplan to make those parts field replaceable.  I think that's the way the EPA want it back then, as they didn't want the public to mess around with fuel mixtures.

I don't think I'm going to find specific info about the "slo-jets" clogged, or maybe they are supposed to be solid in the middle? I can't see thru them, or blow air thru them.

The slow jets have a restriction deep inside that brass tube that is the actual orifice.  The orifice is precision hole #42 or 0.42mm in diameter (0.0165 inches).  If you wish to poke something through that hole, make sure it is smaller than that.  Others have used a guitar string, but be warned that guitar strings are made of harder metal than the jet orifice material.   So, there is some risk of damage with that method if you are careless.

You have pulled he slow jets out, right?

Cheers,

[jason teamshralp]

Slow jet is the lower post? If so you just pulled it out with pliers?

[ugmold]

Thanks for the replys!

What I have been doing is one carb at a time, I have stripped all jets, floats etc and rubber parts off before I soak overnight in a parts cleaner can. The jets etc I have been cleaning with carb cleaner, pb blaster, seafoam etc. The first 2 carbs I cleaned (haven't strted on 3 or 4 yet) I dipped in the parts cleaner with the slojet in, I didn't know it could be removed, since I have pulled them out, I have soaked in carb cleaner, tried to blast with air and poked a bit with a small wire.

Thanks to the post informing me that you should be able to see thru the slo jets...I'll get there I hope. The float setting seems a bit mysterious as (look at pic) it hangs like the tang isn't doing much, this is a much different set up than my other Honda carbs (I got a bunch of bikes) http://www.goomer.com/honda/ so any help with this would be much appreciated.

So glad I found this forum with a bunch of other folks crazy about old rice!

ugmold

[cbass*gxc]

Hey ugmold I dont know which section you are looking at but I didnt realize until later that the section for the 78k carbs is at the very end of my manual.  Its after the supplement to cb550k1.  There are more detailed pics of our carbs there.

[ugmold]

Thanks for the tip Jay....I have only had the manual for about a week and didn't notice an appendendum. BTW, your bike looks great!

ugmold

[cbass*gxc]

Thank you.  I do not know exactly which manual it is I have, so I cant say if it is the same as yours but if you got it from here, then it should be the same.  I did the exact same thing as you on my carbs.  I did one at a time so I could see how they went back together.  I did not take my slow jets out when I soaked them the first time but I used my compressor to blow them out.  I had to clean them again due to some bad gas (on the bike and when I blew the compressor on them I could hear air coming into the carbs.  I like the idea of using a guitar string to clean them.  If you go this route take your slow jet with you to the music store so you can see if they fit and only have to make one trip.

[ugmold]

My manual is a Clymer (M322) for CB350-550, 71-78. Covers too many years and doesn't have the updates in the bake con sarnit. Did you set your floats? I think I can manage the slojets, got plenty of guitar strings, music is another fanatical hobby of mine.
ugmold

[cbass*gxc]

http://www.sohc4.net/files/HSMCB500550.pdf

That is the good one.  And it is complete unlike the other links.  No I did not have to set them, they were right how they were.

[ugmold]

I think visually the problem I have with the floats is that they are not parallel to the carb base, and if they were, it would be a set measurement at that point. Make Sense?

Thanks for the manual, it doesn't seem to mention anything about this however.

ugmold

[KEVINM]

I heated mine up with a  propane torch until it glowed and the crud cooks out. Use a welding tip cleaner to clear it. I spent about an hour per jet to clean each. Make sure the little emulsion holes on the side are clear. I soaked mine in GM upper cylinder cleaner. I also used sea foam. I also found an easy way to install the carbs.  I used two long wood clamps to draw the carb bank back onto the engine. spray the inside of the rubber tubes with silicone and then put a clamp on each side of the carb rack. the clamp goes between the piece that joins the carbs and the exhaust flange. draw each side in a little at a time. mine went on in one minute.

[ugmold]

Success!

In the words of Jim Morrison "Break on thru to the other side, ya" The guitar string worked well. I also heated one up with the torch, but found I didn't need to on the 2nd.

I am still at a loss on how to set this weird float?

Thanks much to all on a subject.

Now how about the float?

ug

[TwoTired]

I am still at a loss on how to set this weird float?

Thanks much to all on a subject.

Now how about the float?

It's the same as any other float, any part of the float that is farthest away from the bowl seating surface must be at the specified measurement (12.5mm) when the needle has just closed in the seat.

Be certain not to reinstall your floats upside down.

Cheers,

[ugmold]

From the picture I have posted the floats are correct, are they not? They were all this way. I have now cleaned 3 of the 4 carbs (inner 2 last) and as I was pulling them off the choke and throttle rods (which couple the carbs) I realized the springs kind of went awry...uhh oh...Anybody have a picture of how they are supposed to go?

Still feel a bit vague on the float setting?

ugmold

[ludite13]

http://www.sohc4.net/files/HSMCB500550.pdf

That is the good one.  And it is complete unlike the other links.  No I did not have to set them, they were right how they were.

Hi, Thanks for posting that link.  I will e poring over this material soon when I am doing my 78 55k carbs.  I will however have to read thru the "Gear#$%*" section in the engine chapter!

-James

[jason teamshralp]

[straightpipez]

I'm in the process of doing the same thing. I just reassembled the carbs and all the bowls leak from where they join the carb body, anyone have clues?

I used new gaskets from Bike Bandit.

Also every breakdown and manual is rather vague when it comes to rebuilding these things.

[anparkinson]

My CB550 pull out slow jets were blocked when I got mine after it had been sitting for 12 years. They should be 0.42mm I believe so I bored them out loosely with a 0.4mm model drill.

The bike runs perfectly now across the whole rev range and pulls really strong.

[bhkrause]

Hi, Forrest.  Figured I'd move over here, in case some of those 750 folks over at yahoo get miffed at non-750 discussions..

The floats aren't parallel to the base when you're measuring them, and you can't measure them with the carb tipped onto it's top.  The carb has to be placed sideways with the float hanging down - then, with the tang just touching the tip of the float valve and the float valve seated, you measure from the gasket mounting surface to the point of the float farthest away from the gasket surface.  It's a pain - do this first, then use the clear tubing method that I mentioned on the other board.

PM me off list, you can call me or IM tonite and I can walk you through this is you want.

bk

[ugmold]

Thanks BK,

I think that explains it well. I assume inverting the carbs to do this will cause the tang to compress and give a false reading?

ugmold