Topic: 1978 CB550... I tried to keep it stock, I failed.

[BLAC]

I added a bike to the stable with the intention of just having a nice/reliable and 'stock classic' to ride.  With the big comfy seat, I might actually get my girl friend on the back of this one...

Here she is, a 1978 CB550K with 11k miles.  She is far from perfect but a very nice survivor.  All stock with the addition of a PERFECT condition Kerker 4-1 exhaust system with baffle.



Running out of room:


Issues:
#4 carb was PISSING gas so I took off the carbs already and started a rebuild. Someone has been in here before and there are mismatching bolts all over the place.  (One of the carb bowls actually had a "tighten only" screw head on it, I hate all previous owners... )

The side covers are not matching, one is a early model and the other is a late.  They do not have emblems on them either and have been repainted but don't look great up close.

The master cylinder was leaking so I pulled the reproduction unit off of my other project and slapped it on here.  So far it seems to work great, but the brake is rubbing just a little bit when Im pushing it (its not locked up or anything, there is just a little resistance).

Tires are DRY to the bone and cracking.  I have some Avons on the way.

[BLAC]

First question/debate... What to do with the carbs...

I have read that these later style carbs are a pain in the ass and not as good as the early 550 carbs.  Should I just rebuild these or get a set of early carbs + manifolds and throw them on?

The bike has the Kerker 4-1 and a Uni Pod filter in the airbox, but all the carb jetting is stock, so it was running a little rough.

Would y'all recommend rebuilding the stockers and correcting the jetting or ditching these and going with an early style?

[markreimer]

I think #2 isn't supposed to be adjustable. That is the baseline and you sync the other three to that cylinder. That's how my 350F carbs are!


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[Stev-o]

I had a '77 550K with stock exhaust, it was too quiet. The Kerker will sound much better.

Stock airbox with Uni pod filter??

[bwaller]

Mark's right, adjust the other three to match #2.

There's nothing wrong with the PD's, clean em up and run em! I use those on a 592, the only potential oddity was having to increase the pilot jet from a 42 to 46 with a tapered jet reamer in order to get it perfect. Quite a jump but I attributed that step to those carbs supposedly designed "leaner" considering tighter emission standards of the period. You shouldn't need to worry about that anyway.

[Bankerdanny]

The later carbs are fine and the idle advance cam on the choke shaft is handy. The stock jetting is a bit on the lean side through and the exhaust/filter combo may exacerbate that a bit.

I think that the spacing is slightly different too so older carbs might not match properly with the later intake plenum.

[SOHC4 Cafe Racer Fan]

I struggled to keep my 550 stockish.  My latest transgression was the conversion to classic-styled modern brakes.  Get this one to be a clean runner, but stay focused on the mono-shocker!

[BLAC]

I struggled to keep my 550 stockish.  My latest transgression was the conversion to classic-styled modern brakes.  Get this one to be a clean runner, but stay focused on the mono-shocker!

I hear ya and totally agree.  I just want to get this one healthy.

[BLAC]

I think #2 isn't supposed to be adjustable. That is the baseline and you sync the other three to that cylinder. That's how my 350F carbs are!


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Ah life saver!  that is great news 

[BLAC]

I had a '77 550K with stock exhaust, it was too quiet. The Kerker will sound much better.

Stock airbox with Uni pod filter??

I started it and reved it up just a little bit before buying it.  The exhaust sounds great, not too loud to ride everyday but also much more character than the stock whisper

And yes it is a Uni filter in the stock airbox.  It is basically a big foam unit in there.  not sure on the reviews on those but it is brand new.  he was installing it as I pulled up to buy the bike

[BLAC]

Mark's right, adjust the other three to match #2.

There's nothing wrong with the PD's, clean em up and run em! I use those on a 592, the only potential oddity was having to increase the pilot jet from a 42 to 46 with a tapered jet reamer in order to get it perfect. Quite a jump but I attributed that step to those carbs supposedly designed "leaner" considering tighter emission standards of the period. You shouldn't need to worry about that anyway.

that got way to technical for my peanut brain, but I will get these rebuilt and give them a go

For my stock motor with the foam filter and the 4-1, I am planning on rebuilding the carbs to the factory settings then running it to see if it too lean with the exhaust/filter.  Does that sound like the right plan or would you advise to make any tweaks to the settings while I have it apart now?

[bwaller]

Sure start with stock settings. I seem to recall from years ago that TwoTired ran a Uni foam filter in one of his bikes and it was considered a positive result.

[flatlander]

And yes it is a Uni filter in the stock airbox.  It is basically a big foam unit in there.  not sure on the reviews on those but it is brand new.  he was installing it as I pulled up to buy the bike

the uni filter works, if cleaned and oiled periodically. but the stock paper filter flows better:
red = uni filter
blue = stock filter
everything else kept the same.



you're probably not too concerned about performance if you keep the bike stock... but now you know

[BLAC]

Very interesting, thanks for posting that up, ill change it out to a paper filter if I find one come up for cheap.

Also I am looking for a left fork ear and right side cover 

[BLAC]

I recently ordered 4 genuine Honda carb gasket kits for my 1978 cb550, but it looks like the cb750 might also use this same rebuild kit?

Can someone confirm that it is indeed the same kit for both models?  I think they are the same but took the leap once I found an auction about to expire at a screamin deal.



follow up question, This kit did not include the tiny little washers and the PO must have lost one, because one of the carbs didn't have one..., anyone know of a place I can buy one?

[SF]

Is your old brass no good?


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[BLAC]

The old brass should be fine, I'm going to use the stock brass after giving them a good cleaning, but the gaskets were pretty crispy.

UPDATE:  my last comment for clarity.  I'm missing one of those tiny washers.

[BLAC]

Issues found in the carbs:

• Missing one of the tiny washers on the pilot jet
  
• One of the float valves feels like it has a stronger spring than the other three (maybe one aftermarket one?)
  

Im going to give the DIY soda blaster a try to clean the bodies up, fingers crossed

[HondaMan]

The carb kits are not the same as the 750's of the era.
I might have one of those washers left in a set of PD41 carbs from a 750K7 that I use as parts for others?
You can make those carbs work better if you slightly enlarge the holes in the emulsifier tubes, above the mainjets. They are a little too small, and with ethanol-laced gas this makes them REAL cold-blooded and weak on the low RPM end. It doesn't help that the spark advancer comes on too soon: if you clip off at least 1/2 turn of one of the advancer springs, it will pull 2 of you from a stop MUCH better.

PM me with your address: I'll go look for the little washer in a few minutes.

[BLAC]

The carb kits are not the same as the 750's of the era.
I might have one of those washers left in a set of PD41 carbs from a 750K7 that I use as parts for others?
You can make those carbs work better if you slightly enlarge the holes in the emulsifier tubes, above the mainjets. They are a little too small, and with ethanol-laced gas this makes them REAL cold-blooded and weak on the low RPM end. It doesn't help that the spark advancer comes on too soon: if you clip off at least 1/2 turn of one of the advancer springs, it will pull 2 of you from a stop MUCH better.

PM me with your address: I'll go look for the little washer in a few minutes.

It looks like the '78 uses the same gasket kits (float bowl gaskets, pilot o-rings and fuel tube o-rings) as some of the 750's.  Im not sure what 750's they are compatible with but these kits fit fine on all of my carbs (minus the included paper top gaskets because the tab holes are located a little differently)

I will look into the advancer and emulsifier tube modification, not sure how large to drill out those tiny holes...

I bought a tiny washer from another member, and had already received new float valves, so I will get these things reassembled shortly! 

Oh and I polished the tops and bottom float bowls, they look pretty good!

[Stev-o]

Float bowls look fantastic!

[BLAC]

Float bowls look fantastic!

Thanks!  I bought just a little cheap-o 'polishing kit' from Harbor Freight. It has a few polishing bits and a couple different colored blocks of compound.  I just attached one of the bits to a hand held grinder and went after it. It only took a few minutes but MY GOD polishing is dirty work... Im still finding grime and buffing wheel threads behind my ears and in my pockets

[Restoration Fan]

Brian,
I can also highly recommend that you purchase the middle weight nitrile gloves from HF the next time (the light blue, thinnest ones break too easily).  It makes it much easier to clean up your hands after any kind of wrenching, sanding or polishing.

Also, if you have a bench grinder, mount the pads on that and it makes the polishing job a bit less messy and much easier to control.

Nice work on the float bowls though.  Pain in the butt to polish stuff but you get to see fairly immediate rewards.

Ron

[BLAC]

In pulling apart the carbs, I noticed that two different style float needles were being used...

Does anyone know which style a '78 should use?

[sethmcalister]

The float on the right appears to be what I have for my '78

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