Author Topic: 1978 CB550K (Read 5611 times)

free85 · « **on:** July 18, 2013, 07:11:38 AM »

Hello. I found my way here thanks to some people pointing me in this direction. I recently picked up an 1978 CB550K that I've started work on. I've read through some of the threads here and this seems like a great resource. At present I'm in the process of waiting on parts (we've got a lot of gaskets incoming). I've learned that waiting on parts is a mutha. That said I have taken my carbs apart and dipped them, after making sure to removed the plastic/rubber parts. They're spread out on a table waiting for gaskets to arrive so I can put them back together (hopefully).

SOHC4 Cafe Racer Fan · « **Reply #1 on:** July 18, 2013, 07:45:46 AM »

What is the condition of the bike and what are your plans for it?

Bankerdanny · « **Reply #2 on:** July 18, 2013, 08:06:48 AM »

Free, welcome. I live in Evanston these days, but I grew up in Mokena and spent 2 years at Joliet JC in the early 80's.

This site is a fantastic resource. Do use the search function before you post a question though, you will find 95% of your questions have already been asked and answered, probably more than once. Also, we love pictures, especially when asking questions.

On the carbs, just replace the gaskets and o-rings, keep all your original jets, needles, etc. Those parts are unlikely to be worn out and staying with factory parts reduces the possibility of tuning issues.

What are you planning? Resto, cafe, brat, something in between?

free85 · « **Reply #3 on:** July 18, 2013, 09:52:55 AM »

Thanks to both of you for the welcome.

The bike itself seems to be in better shape than I originally thought it was. It has 20k on it. Initially the battere was dead but it would turn over when hooked up to a charger.

I brought the bike home, replaced the spark plugs (the old ones were foul and the gap was WAY off), and put the battery on a charger. After connecting the battery up the the bike it turned over fine, and would run as long as the choke wasn't all the way in. When the choke went all the way in the bike would die out.

The gaskets/boots leading to the stock airbox were pretty chewed up (large cracks etc). I'm finding it difficult to find an airbox filter and gaskets/boots. I pulled the cover off the points to have a look and the points/condensers seem to be brand new.

I had planned on keeping the original jets/needles on the carbs as only the gaskets looked like they needed replacing.

My overall hope for the bike is to cafe it, some day, in the near future. But right now I want to get it on the road and get a feel for how it is running and how I might make it perform better before I do the "typical newbie" thing and tear it apart and detab it and make a bunch of "enhancements" blindly (because I don't have a baseline for how the bike was running).

Bankerdanny · « **Reply #4 on:** July 18, 2013, 02:35:42 PM »

Use a Honda parts dealer site like CMSL (or my favorite powersedge.com) to see the parts fische and get the factory number for any part you want. Then do an internet search on the part number and see who has it. eBay listings will come up too.

The '77-78 filters are out there, but they can be a challenge to find and as a result they are more expensive than the 74-76 filters. Keep checking eBay and one will turn up. Be careful to confirm the application though and understand the difference between the models.

For example, The 77 and 78 550K use the same filter. Some of the current eBay listings show a filter that fits 75-77 CB550, which might lead you to believe it would fit yours too. But it won't, the 550 they are referencing is the CB550F, which was made until '77 used the same basic carb and airbox as the 74-76 CB550K, and is completely different from the carb and airbox used on the 77-78 CB550K.

Uni makes an aftermarket reusable filter the uses the stock airbox setup.

You can put a wanted ad in that section of the board. Someone is certain to be putting individual pods on their bike and you can get the rubbers from them.

free85 · « **Reply #5 on:** July 19, 2013, 06:06:07 AM »

Sounds like how things have been going. I put new brake pads on the rear wheel last night. I looked at the bearings and the hub and everything looks good. That said I don't have the tools (or the knowledge) to pull the bearings so I'm thinking I might take them to a local shop and see how the wheels look when eyed up by a professional. Other than that I'm waiting for my carb gaskets to come in so I can get some room on the bench to pull the heads to put in new gaskets.

free85 · « **Reply #6 on:** July 19, 2013, 09:08:27 AM »

It's looking like I'm going with a uni filter. I have heard decent things. Now if I can just find the rubber leading to the airbox we might be in business!

From reading above I'm getting that the 77 and 78 550Ks should have the same air box setup, yes?

Bankerdanny · « **Reply #7 on:** July 19, 2013, 10:36:38 AM »

Yes, that's right.

free85 · « **Reply #8 on:** July 20, 2013, 10:58:29 PM »

So we did some work today... Pulled the cylinder. Everything seemed to go well. I'm posting up some pictures. Input is always very welcome. Cell phone pictures are the best I can do, gents. Apologies if they're less than great.

I suppose it starts here:

http://www.flickr.com/photos/99171087@N06/9333226154

Camshaft wear:

http://www.flickr.com/photos/99171087@N06/9333231310/#

Gasket came up pretty alright:

http://www.flickr.com/photos/99171087@N06/9330437685/#

And the way the cylinders look:

http://www.flickr.com/photos/99171087@N06/9333239132/#
http://www.flickr.com/photos/99171087@N06/9330439869/#

And I took this one because I was just geeked up about the whole process:

http://www.flickr.com/photos/99171087@N06/9330433247/#

free85 · « **Reply #9 on:** July 20, 2013, 11:14:55 PM »

I was thinking of getting a cylinder gauge and micrometer and checking the specs myself but, I'm going to guess that I won't be terribly accurate as it would be my first go around at it. Any one have any suggestions? Have a machine shop check them for me?

free85 · « **Reply #10 on:** July 26, 2013, 07:13:58 AM »

Sorry for the gap in updates (for those of you following along). I've been working on scraping the old gasket off of the head/cylinder so I can clean them up and get them ready for reassembly. I'll post some pictures up shortly (and do it right this time so you gents don't have to follow links to see them). I'll be doing some solid work on her this Saturday and Sunday after I finish up my Motorcycle Riders Course.

free85 · « **Reply #11 on:** July 27, 2013, 02:04:29 PM »

I was excited... the gasket kits for my carbs came in and I was going to finish my rebuild. Unfortunately I'm missing the washer that goes to the needle before the O-ring goes on. And, as I went to install the top gasket the most interesting thing happened:

All 4 kits are just like this.

Bankerdanny · « **Reply #12 on:** July 29, 2013, 11:28:05 AM »

There must be another similar carb with offset locator pins. the kit I got for my '77 K bike in 2011 was exactly the same.

Fortunately you can see that the seal is only around the edges and not the locator pins so, as I mentioned in your SOHC4 thread about this, you can just use a drill bit to add the proper second hole.

free85 · « **Reply #13 on:** July 30, 2013, 08:55:15 AM »

I saw that post on my "PD46C Parts" thread. I was happy when I did. I'm looking forward to putting the carbs together soon (one small o-ring I can't quite figure out), and moving on to laying down the cylinder, head, and tappet gaskets as I reassemble the rest of the engine. I have some valve lapping to do first though.

And thanks Bankerdanny, for the heads up and help.

free85 · « **Reply #14 on:** July 30, 2013, 12:24:02 PM »

Out of curiosity I pose the following for comments:

I've been reading about reassembly and noted that it might be a good idea to get a hone so I can get some crosshatches in the cylinder so the piston will seat well. My piston rings appear to be fine, and so will get cleaned (along with the piston) and reused. I'm considering using one of the ball type hones... I did do a search, just looking for some input (seems like at $30 this isn't a bad idea and is, apparently, hard to screw up).

As for the size I am under the impression I need to get the nearest size to my cylinder bore (which I think is stock, I do not have a cylinder bore gauge at the moment).

knowsnothing · « **Reply #15 on:** July 30, 2013, 01:12:38 PM »

Its always a good idea to get some new rings when doing a hone. Also, don't buy anything until after you hone it. If the cylinders go out of spec afterward, you will need to go up to the next step piston, i think its .25 over.

TwoTired · « **Reply #16 on:** July 30, 2013, 01:34:24 PM »

Why did you take it apart? Actual wear indicators, or curiosity?

Did you remove the rings from the pistons? If not, why do you think the rings no longer seat properly in their mated bores?

dohcdelsol93 · « **Reply #17 on:** July 30, 2013, 01:52:41 PM »

if you already have it apart i'd have the cylinders checked to make sure they are in tolerance for stock bore.

If not you'll be wasting your time putting old rings back in (or new std size rings for that matter) and I don't want to get started on the shade tree's that put in oversized piston rings on stock pistons and file them down to the proper gap to make up for a cylinder with too much wear.

I work at a shop that has built many a motorcycle engine...and we have had to re-do a lot of half way done jobs in the past.

my 1976 cb550 cylinders with over 36K on them checked out in tolerance for stock bore, I had the cylinders honed then coated along with pistons cleaned, kind of a just in case back up. So you might be ok. I'd just want to be 100% sure before i replaced them. PO complained of oil consumption so he tore the bike apart and it sat that way some 20 years before i purchased her.

free85 · « **Reply #18 on:** July 31, 2013, 06:13:12 AM »

Quote from: TwoTired on July 30, 2013, 01:34:24 PM

Why did you take it apart? Actual wear indicators, or curiosity?

Did you remove the rings from the pistons? If not, why do you think the rings no longer seat properly in their mated bores?

I took it apart mostly out of advice to do so, and partly out of curiosity. I did not remove the rings from the pistons. My initial plan was to put the bike on the road after doing a general freshen up, get a baseline idea for how the bike runs, and then cafe it later (after deciding what I'd like to improve).

I have no reason to think that the rings do not seat properly in the bores. I have not trouble admitting that I'm very new to this and the idea of honing up the bores just sounded like a good idea (the whole "well... while I'm in here" thought that I'm sure most of us newbies have).

I'm leaning towards cleaning up the pistons and beginning reassembly. The bike will be coming apart in totality this winter, and, fingers crossed (and finances available) getting bored and some other fun things. I've been enjoying the project to this point so I'd like to learn to do as much of this as possible, but I know it's a slow process, and some of it simply isn't for me right now, and may never be (I am not a machinist and I know this). Right now I'd be happy to learn to reliably use a cylinder gauge and things of that nature.

TwoTired · « **Reply #19 on:** July 31, 2013, 08:59:37 AM »

There are few that can build an engine as well as Honda. Honda has had lot's of practice, test subjects, and experience. Before you try to improve on what they did, you might consider that. No doubt you can learn to do those things. But, mistakes can be costly for random meddlers or taking cues from unknowledgeable well meaners. A fully equipped shop to refurbish every component in the engine is going to cost more than ten complete bikes. More often that not, simply fixing what is broke, will get you many miles down the road and the best ROI.

The best example that repeatedly happens, is when a curious person dismantles an operating Cb550 engine, and ignores the warnings in the shop manual about cylinder cover installation, cranks down the cylinder cover bolts, and bends several of what used to be good valve stems, and cracking the valve guides. All that "work" and the engine no longer operates, without hundreds of dollars in new valves and guides, or a replacement cylinder head.

If you have leaky gaskets, that you simply can't live with, replace the gaskets. The "while-I'm-in-here" syndrome can become quite costly (as well as educating).

Nothing wrong with wanting a brand new 1978 Honda. But, few want to spend the time and money to actually build one to new specs.
Even new bikes are not perfect, btw. There is a reason that warranty's limit repairs to correcting what is broke and not include a reset to zero wear of the entire machine.

Having said all that, there is certainly value to education, and there is a rationale that supports sacrificing the entire machine to achieve that goal. But, that would also leave one less intact antique available to the general populace.

Down from soapbox, now. Good luck!

free85 · « **Reply #20 on:** July 31, 2013, 10:05:05 AM »

No need to get off the soap box, TwoTired. I know that Honda had WAY more engineering hours than I do. Right now I want to take my "didn't used to run" cb550 and make it run. The kind of "enhancements" I'm talking about are mild/fun performance things, over bore, 650 cam, that kind of thing. That said right now I want it to run, turn, and stop. So the at present I intend to put it back together and see if I installed the gaskets correctly etc. Basically this take apart was to do maintenance. I do want to cafe the bike at some point, but first I want to ride around and enjoy it... It would be nice if it didn't look like crap all the time too, so I've scrubbed on it a bit and removed some of the rust. She deserves that.

free85 · « **Reply #21 on:** August 21, 2013, 06:32:29 AM »

Well... I haven't given up, just been working on the bike. Updates (for those of you learning from my mistakes or enjoying the entertainment):

Carbs: Finally got the carbs rebuilt. The jets were cleaned and put back in and everything looked good. Those felt O-rings were an awful lot of fun, but they're in, and seem to be doing their job.

On choke cable adjustment: If anyone had the PD46C carbs and is struggling to get the choke arm to work appropriately that weedy little impossibly small looking spring WILL actually tie the two arms together. I know it doesn't seem like it will, but it will. What finally worked for me was adding another wrap to the spring. Works like a charm.

Carb installation went fairly well. The rubber for the new airbox was soft and pliable so that wasn't too terrible.

I added new fuel line for the bike and a new inline fuel filter after the petcock going to the carbs, seems to work just fine.

Hooked up the new box Mark/HondaMan sent me for my points and everything seems to work just like it should.

Started the bike and heard her jump to life for the first time! Outstanding feeling. The carbs are terribly out of sync, and my throttle cable has to be off (throttle on the handlebars doesn't return to position when you let go, you have to roll off to get it to do so).

Suddenly I notice: a low RPM rattle. Turned the bike off and laid down for the night feeling good about it working but worried about the rattle. I think the cam chain adjuster isn't doing its job...

And I think this means a new cam chain adjuster... and new gaskets when I install it. I'll know in a little while when I take a look at the adjuster to see if it does it's "auto adjusting" magic or not.

Update pending, gentlemen.

Bankerdanny · « **Reply #22 on:** August 21, 2013, 07:14:04 AM »

I had forgotten about that damn spring. That was the hardest part of the reassembly and of course none of the dozen pictures I took before disassembling the carbs included a clear shot of that part of the mechanism.

free85 · « **Reply #23 on:** August 21, 2013, 07:30:34 AM »

Quote from: Bankerdanny on August 21, 2013, 07:14:04 AM

I had forgotten about that damn spring. That was the hardest part of the reassembly and of course none of the dozen pictures I took before disassembling the carbs included a clear shot of that part of the mechanism.

This is, 1000 times over, how I felt about that thing! The whole thing is a little "rough" right now as far as the choke and throttle levers go. Everything is a little difficult to operate but I'm sure that can be ironed out with some tinkering.

I am, however, worried that the cam chain tensioner is toast... And Honda doesn't seem to be supplying them anymore. That and I REALLY don't want to spend more money on gaskets (the bike has run for a total of maybe 10 minutes on the new ones).

Getting any riding in, Danny?

free85 · « **Reply #24 on:** August 21, 2013, 08:10:51 AM »

HA! My cam chain tensioner works as I think it should when #1 is 15deg ATDC! I ran through the adjustment per manual and it autoadjusted. I think this will remove said rattle.

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Author Topic: 1978 CB550K (Read 5611 times)