1976 CB550 K2 Engine Rebuid/Overhaul Suggestions

[titan5699]

Hello everyone!

I have a 1976 Honda CB550K2 with about 40,000 miles on it. The bike runs fine, but has started to develop a small oil leak towards the end of the riding season from one of the seals behind the side chain cover. Being that it is winter time in NJ and averaging about 20 degrees outside daily, I wanted to look into getting the engine rebuilt so she's ready for when the weather breaks.

I am not very knowledgeable in this area and have zero experience with this particular engine. That being said, I wanted to pool together the knowledge of all the people on here who have done this before. I have heard about doing some mods at this stage for more power, but I want to see what is worth it and what I should avoid.

First off, I live in Central NJ, on the Delaware River side. I have contacted Redline Motorcycles on NJ-38 near the Pemberton area to do the rebuild. They said obviously this is the time to do it, the sooner the better before they get crazy busy when the weather starts turning around. Does anyone have any experience with these guys, or know of any other shops in this area (mechanics, speed shops, etc) that know what they are doing with CBs?

As for the rebuild itself. I am not looking to go crazy with the mods, I am on a budget, $1000 - $2000 mark all said and done would be ideal. Sure I would like more power, but I'm not looking to stress out the engine as if it were a race bike. Just want some more power than I have now, and something that is going to be good for everyday use, touring, commuting and reliable. Also not looking to spend crazy money, I want to get it done right and do it once, so doing improvements now while the engine is open. Possibly reusing certain internals that are still good, replacing what is bad or replacing what can fail in the future as preventative maintenance.

Mods I currently have: 4-into-1 exhaust, UNI pod filter intakes, rejetted stock carbs

I have heard of a few things to do for more power on these bikes. One being to replace the 550 cam with a SOHC 650 cam. Is it worth it? Do I have to make other mods, like 650 valves, timing chain..?
Another thing is switching out the 1976 stock carbs for stock 1978-79 CB550 carbs, as they are easier to tune. I have rebuilt my stock carbs and rejetted them to match the intake and exhaust mods, but I would agree that they are not easy to tune, I still have dead spots in the throttle (could also be due to poor tuning on my end). Thoughts?..

As for other internals. Anything that should be done as preventative maintenance? Should I bore out the cylinders to a bigger size, even if the bores are good as is?.. Is it easy to find stock replacement internals, or bigger sized aftermarket parts?

I want to have the head ported and rebuilt as well. Any other improvements that could be suggested here?

Lastly, I want them to go through the trans and replace clutch discs, I have no idea when they have been done last. Also I might take the opportunity to redo some electrical, like electronic ignition and maybe see about having the charging system looked at.

I greatly appreciate any suggestions and help and for taking the time to read this. I am new to this but want to have the knowledge to do the job right.
Please help me to not make any major financial mistakes (I can't afford to), and help me keep this good ol 39 year old girl on the road and running forever! She has treated me well, now it's time I reward her.
Thanks in advance!
-Rob

 

[2_DONE_THE_TON]

Hi!

Oil leaks can be a PIA since some oil gaskets have ridges so you ll need to tear down to the bottom case...i had this issue ib my kz400.
As for electrics i can recommend you buying a sparck moto harness,freshly built and fully customised to your needs.

 

[carnivorous chicken]

Before you do any of this stuff, let me say/ask three things.

Are you sure it's not the seal for the shifter lever? Those can go bad and drip (and eventually pour) oil. Very easy to replace, very cheap seal.

Have you or a previous owner upgraded to an o-ring chain? Some thicker chains on CB550s will wear away the backside of a seal on the transmission, which can then leak oil out of the cover.You can avoid a full rebuild by draining the oil and using something to try to block off the seal (silicone sealant, e.g.). This can slow or stop the leak, but might have to be done every year or every couple of years, depending on riding. You should also either replace the chain or you could insert a thin washer behind the sprocket to bring it out just a tad, so it won't rub away on the seal or on the repair. I've done this with success.

Third, could be your oil pump O-rings or oil pressure switch. All easy and cheap replacements.

All of these can be seen here: http://forums.sohc4.net/index.php?topic=37726.0

The second is going to be the most problematic, but like I said, it's possible to stop that leak without a rebuild. Once you figure out where the problem is, then you can decide what to do.

Final bit of advice: don't fix what ain't broke, and don't go looking for things to be broke when they ain't.

 

[titan5699]

Before you do any of this stuff, let me say/ask three things.

Are you sure it's not the seal for the shifter lever? Those can go bad and drip (and eventually pour) oil. Very easy to replace, very cheap seal.

Have you or a previous owner upgraded to an o-ring chain? Some thicker chains on CB550s will wear away the backside of a seal on the transmission, which can then leak oil out of the cover.You can avoid a full rebuild by draining the oil and using something to try to block off the seal (silicone sealant, e.g.). This can slow or stop the leak, but might have to be done every year or every couple of years, depending on riding. You should also either replace the chain or you could insert a thin washer behind the sprocket to bring it out just a tad, so it won't rub away on the seal or on the repair. I've done this with success.

Third, could be your oil pump O-rings or oil pressure switch. All easy and cheap replacements.

All of these can be seen here: http://forums.sohc4.net/index.php?topic=37726.0

The second is going to be the most problematic, but like I said, it's possible to stop that leak without a rebuild. Once you figure out where the problem is, then you can decide what to do.

Final bit of advice: don't fix what ain't broke, and don't go looking for things to be broke when they ain't.

Thank you for your input.

I can't be sure whether the leak is coming from the shifter arm or not, I want to say it's one of those black round seals above it, but can't be certain especially because its been a little while since I've taken a look. To my knowledge, no one has put an O ring chain on it. I replaced the chain and neither the old or new one is an O ring chain.
Once I first noticed the oil drip, it was coming from the opening of the back of the side cover where the chain enter/exits. I pulled the cover thinking it was either from over lubing the chain at some point (I just recently cleaned and lubed the chain and could have gone over board) or just old grease and grim making its way out. So I pulled the cover off and noticed it was oil and it was clean newer oil. Seemed like it was coming from higher up than the shifter arm, and it wasn't leaking out of where the arm goes through the side cover, just out of the back. You'd think that if it were leaking from the shifter arm it would be coming out from where the arm runs through the cover, since that is the path of least resistance.

Not sure if this make a difference but when I first got the bike I always put full synthetic oil in it and put a good amount of miles on the bike without issue. I was told that I shouldn't run synthetic oil on an older bike because it wasn't around at the time and wasn't meant to run with that type of oil. So I switched to a premium Honda conventional oil, and shortly after that is when I noticed this leak. On the plus side, the conventional oil seems to burn off less than the synthetic did.

As for the rebuild, it can use it. At least the head. The head gasket is in need of replacement, covered in old slimy oil and has chunks where it has ripped off. Since I've had it, it always had a slight leak/seeping from around the gasket when warm, and that just seems to be getting worse. And like I said, she has over 40k on her and sat for 20+ years before I got her. This is my only bike and I would like to have the peace of mind of a rebuilt reliable engine when Im on longer out of state trips. Over the summer I went on a 300-400 mile trip down to Ocean City MD for the bike fest, so I'm not afraid to do the miles, but afraid of not making it home without it being behind a pick up. I don't want to take that trip again and have a break down, seriously hampering the trip and holding up the group (which consists of all Harleys, lol, but the CB held her own and got way more looks Most of which were good looks, I think.. lol).

Also my fiancé and I like to ride together and at hwy speeds I feel bad for the bike, Im not exactly light, as the bike is just screaming in the RPMs and as I wait for the head gasket to finally blow.

Bottom line, I just want her to be reliable for the season and I don't want to have to worry about it on long trips. I plan to keep her running forever!

 

[carnivorous chicken]

A top-end rebuild is a lot less of a job than splitting the cases, so you should still track down that leak. Open the cover, clean the whole area, start the bike and let it idle, and look for the seep/drip. You've got to know what you're dealing with before you decide what to do, although it sounds like the top end is definitely part of the plan.

 

[titan5699]

A top-end rebuild is a lot less of a job than splitting the cases, so you should still track down that leak. Open the cover, clean the whole area, start the bike and let it idle, and look for the seep/drip. You've got to know what you're dealing with before you decide what to do, although it sounds like the top end is definitely part of the plan.

Yea, you are right, it's worth doing that just to see where its coming from..
I should also probably check with the shop I was speaking with and see if the price they quoted (around about price) is for just the top end, or actually splitting the case.

And if Im not mistaking, they should be able to service the clutch without having to split the case too.