Author Topic: '76 cb550 oil in the exhaust.  (Read 441 times)

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Offline kerryb

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'76 cb550 oil in the exhaust.
« on: August 04, 2023, 06:19:02 AM »
Trying to diagnose what might be letting oil into cyl #1 only.  The owner thinks it must be a failed valve stem seal.  I think it could be related to rings.  After startup, the engine slowly begins to smoke, then oil leaks from the drain hole in the #1 exhaust.  I suppose the first test would be compression and leakdown test.  Would a failed head gasket also be a likely culprit.  I may want to buy this bike,  so knowing what to fix first would be a plus.
Suggestions of test ideas welcome.
p.s. 10,000 original miles, all stock parts.
intrigued by the wail...seduced by the scream.

Online denward17

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Re: '76 cb550 oil in the exhaust.
« Reply #1 on: August 04, 2023, 06:38:46 AM »
Whatever it is, just know that at least the head has to come off to inspect, to either replace valves/vavle guides, seals or whatever.

Once the head is off, you have to inspect cylinders/pistons/rings.

Oil in the cylinder is coming from rings or valve guides or valve guide seals or o-rings between head/cylinder.
« Last Edit: August 04, 2023, 09:12:02 AM by denward17 »

Online Stev-o

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Re: '76 cb550 oil in the exhaust.
« Reply #2 on: August 04, 2023, 06:43:29 AM »
  I think it could be related to rings. 

That is where I would put my money.
'74 "Big Bang" Honda 750K [836].....'76 Honda 550F.....K3 Park Racer!......and a Bomber!............plus plus plus.........

Offline calj737

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Re: '76 cb550 oil in the exhaust.
« Reply #3 on: August 04, 2023, 07:07:13 AM »
Smoking while running generally points to rings, but if the bike truly only has 10k miles on it, I’d find that hard to believe unless the motor has sat for a long time without operating and the rings are gummed up.

Oil dripping from the drain hole… are you dead certain it’s oil and not carbon/condensation?

A quick compression test of all 4 cylinders would be my first test. If #1 is truly down compared to the others, then it’s rings. If they’re all close to equal, it’s seals. It is possible to replace the intake seals without removing the head, but is better to pull the head and less hassle in the long run.fortunately a 550 head can be pulled with the motor in the frame.
'74 550 Build http://forums.sohc4.net/index.php?topic=126401.0
'73 500 Build http://forums.sohc4.net/index.php?topic=132935.0

"Of all tyrannies, a tyranny sincerely exercised for the good of it's victim may be the most oppressive. It may be better to live under robber barons than under omnipotent moral busybodies. The robber baron's cruelty may sometimes sleep, his cupidity may at some point be satiated, but those who torment us for our own good will torment us without end for they do so with the approval of their own conscience." - C.S. Lewis

Offline kerryb

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Re: '76 cb550 oil in the exhaust.
« Reply #4 on: August 04, 2023, 07:18:41 AM »
Thanks for the replies gentlemen,  I'll start a thread when the engine repair begins.
intrigued by the wail...seduced by the scream.

Offline seanbarney41

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Re: '76 cb550 oil in the exhaust.
« Reply #5 on: August 04, 2023, 07:33:17 AM »
Hold on now!  How long has the bike been sitting?  With low mileage low, the bike can't have been used for long or often.  Has the owner been lubeing cylinders for storage?  Are or were the rings stuck?  Is it really oil?  I have seen where it takes around 100 miles to get all that crap burnt out of the pipe.  If your engine is not broke, please don't fix it.  Everyone seems to think they can build a better engine than Honda did in the first place with a $25 cylinder hone, some rings, and a clymer manual.
If it works good, it looks good...

Online newday777

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Re: '76 cb550 oil in the exhaust.
« Reply #6 on: August 04, 2023, 07:48:59 AM »
Thanks for the replies gentlemen,  I'll start a thread when the engine repair begins.
Stuck rings is my guess with the minimal information given

Is this a bike that was sitting with gas left in it? How long?
Stu
Honda Parts manager in the mid 1970s Nashua Honda
My current rides
1975 K5 Planet Blue my summer ride, it was a friend's bike I worked with at the Honda shop in 76, lots of fun to be on it again
1976 K6 Anteres Red rebuilding project, was originally my brother's that I set up from the crate, it'll breath again soon!
Project 750s, 2 K4, 2 K6, 1 K8
2008 GL1800 my daily ride and cross country runner

Prior bikes....
1972 Suzuki GT380 I had charge of it for a year in 1973 while my friend was deployed and learned to love street riding....
New CB450 K7 after my friend returned...
New CB750 K5 Planet Blue, demise by ex cousin in law at 9,000 miles...
New CB750 K6 Anteres Red, to replace the totaled K5, I sold this K6 at 45k in 1983, I had heavily modified it, many great memories on it and have missed it greatly.....
1983 GL1100A, 1999 GL1500 SE, 1999 GL1500A

Offline ekpent

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Re: '76 cb550 oil in the exhaust.
« Reply #7 on: August 04, 2023, 09:49:58 AM »
Hold on now!  How long has the bike been sitting?  With low mileage low, the bike can't have been used for long or often.  Has the owner been lubeing cylinders for storage?  Are or were the rings stuck?  Is it really oil?  I have seen where it takes around 100 miles to get all that crap burnt out of the pipe.  If your engine is not broke, please don't fix it.  Everyone seems to think they can build a better engine than Honda did in the first place with a $25 cylinder hone, some rings, and a clymer manual.
Agree on that and make sure that cylinder is not flooding out and its a mixture of gas and carbon deposits.  Is the smoke a heavy blue or more of a black color ?  White would be water condensation.

Offline kerryb

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Re: '76 cb550 oil in the exhaust.
« Reply #8 on: August 04, 2023, 12:05:31 PM »
Hold on now!  How long has the bike been sitting?  With low mileage low, the bike can't have been used for long or often.  Has the owner been lubeing cylinders for storage?  Are or were the rings stuck?  Is it really oil?  I have seen where it takes around 100 miles to get all that crap burnt out of the pipe.  If your engine is not broke, please don't fix it.  Everyone seems to think they can build a better engine than Honda did in the first place with a $25 cylinder hone, some rings, and a clymer manual.
Agree on that and make sure that cylinder is not flooding out and its a mixture of gas and carbon deposits.  Is the smoke a heavy blue or more of a black color ?  White would be water condensation.

I was thinking about stuck rings , while we are brainstorming this   it was sitting for awhile, smoke is more light blue than black
I don't want to pull it apart, so I'll try everything else first.  If a carb is overflowing to produce black smoke, then this could be cleared up with just carb work and run time.  That would be nice, but I need to be prepared for the worst!
intrigued by the wail...seduced by the scream.

Online newday777

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Re: '76 cb550 oil in the exhaust.
« Reply #9 on: August 04, 2023, 02:04:22 PM »
Hold on now!  How long has the bike been sitting?  With low mileage low, the bike can't have been used for long or often.  Has the owner been lubeing cylinders for storage?  Are or were the rings stuck?  Is it really oil?  I have seen where it takes around 100 miles to get all that crap burnt out of the pipe.  If your engine is not broke, please don't fix it.  Everyone seems to think they can build a better engine than Honda did in the first place with a $25 cylinder hone, some rings, and a clymer manual.
Agree on that and make sure that cylinder is not flooding out and its a mixture of gas and carbon deposits.  Is the smoke a heavy blue or more of a black color ?  White would be water condensation.

I was thinking about stuck rings , while we are brainstorming this   it was sitting for awhile, smoke is more light blue than black
I don't want to pull it apart, so I'll try everything else first.  If a carb is overflowing to produce black smoke, then this could be cleared up with just carb work and run time.  That would be nice, but I need to be prepared for the worst!
Put a 50/50 mixture of acetone and Marvel Mystery Oil in the cylinders to help free up the rings, for a week, every day move the kick start a little bit to change positions of the rings and pistons(leave plugs loose in the head to release pressure as you kick it. At the end of the week pull the plugs, kill switch off, hit the starter to expell the mix, the run it easy outside as it'll smoke, then take a short 20 mile easy ride to work the rings free. Let it cool, then run another easy 20 miles. Report back. )
Stu
Honda Parts manager in the mid 1970s Nashua Honda
My current rides
1975 K5 Planet Blue my summer ride, it was a friend's bike I worked with at the Honda shop in 76, lots of fun to be on it again
1976 K6 Anteres Red rebuilding project, was originally my brother's that I set up from the crate, it'll breath again soon!
Project 750s, 2 K4, 2 K6, 1 K8
2008 GL1800 my daily ride and cross country runner

Prior bikes....
1972 Suzuki GT380 I had charge of it for a year in 1973 while my friend was deployed and learned to love street riding....
New CB450 K7 after my friend returned...
New CB750 K5 Planet Blue, demise by ex cousin in law at 9,000 miles...
New CB750 K6 Anteres Red, to replace the totaled K5, I sold this K6 at 45k in 1983, I had heavily modified it, many great memories on it and have missed it greatly.....
1983 GL1100A, 1999 GL1500 SE, 1999 GL1500A

Offline kerryb

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Re: '76 cb550 oil in the exhaust.
« Reply #10 on: August 04, 2023, 10:07:12 PM »
Put a 50/50 mixture of acetone and Marvel Mystery Oil in the cylinders to help free up the rings, for a week, every day move the kick start a little bit to change positions of the rings and pistons(leave plugs loose in the head to release pressure as you kick it. At the end of the week pull the plugs, kill switch off, hit the starter to expell the mix, the run it easy outside as it'll smoke, then take a short 20 mile easy ride to work the rings free. Let it cool, then run another easy 20 miles. Report back.
[/quote]

That's a good idea, but before I can report back, I need to own it, register it, & get insurance, & go through the carbs (clear tube test).  So it will be a bit...

Thank you all for the head srart.
intrigued by the wail...seduced by the scream.