Leaking oil from the exhaust ports

[jdsurge]

Hi everyone. I have restored a 1966 CL77 in 2008 and it is in show condition. I won 2nd place in the Keenland Concours show (suprised) and have not ridden it for 5-6 years. I decided to sell it and when the prospective buyer rode it, it leaked oil pretty bad all over the bottom of the motor and inside the right side cover. So a while later, I took off the skid plate and right side cover, wiped off all the oil and ran it for about 15 mins. NO OIL LEAKS. So I put it back together and then noticed that the oil was coming from the exhaust ports, leaking down the engine and blowing over the entire bottom of the engine. It does not burn any oil and I have ask a 30 year Honda mechanic about it and he said he had no idea. I was thinking that maybe some of the oil ports letting the oil go back to the oil sump might be stopped up but before I tear into it again, I thought I would see if anyone has had this problem before? Any help would be greatly appreciated.
Thanks,
JD

[G-Man]

I think we need a bit more information in order to help you here.

a) Did the engine run without leaks when you first restored it?
b) Which part of the exhaust ports? Just one or both? The pipes should be gas-tight so a picture of where the leak starts would be handy.

c) Could the leak be near the ports? Tappet covers, Spark plug area?
d) Did you fit the o-ring seals on the two corner studs between head and barrels?

G

[jdsurge]

Thanks for the quick reply G-Man. Here are my answers:
a) After restoring it, I rode it off and on for about 3-4 months, approx. 75-100 miles. No leaks anywhere.
b) I have just had hip surgery so I can't take any pictures yet but when I saw the leak, it was at the bottom of each exhaust port, just dripping down. I assume I didn't have an air tight seal. I purchased some more copper seals but have not had time to install them. I probably need to look again (when able) to see if the leak was above the port and leaking down but right now, I don't think so.
c) It appears the tappet covers are tight, no leaks but I did have some oil around the spark plug area, no much, and it seams that is because of the typical leakage due to the case iron cylinder into the aluminum head which the cl77's are known for.
d) Yes, the oring seals were installed when I built the motor.

So I did ride this bike for 3-4 months with no leaks anywhere but then again, it sat for about 5 maybe 6 years without running. I thought maybe a gasket was dried up but could only find the leak coming from the bottom of the exhaust port. If I seal the ports up with new copper rings, I wonder if the oil will be blown out the exhaust pipes?
Thanks again for all the suggestions.
JD

[Nick]

Crankcase breather plugged with something? Breather hose kinked closed?

Put some miles on it and see if the problem goes away (or have someone you trust take it for a few rides).

And yeah, maybe new exhaust gaskets would be a good idea, or seal up/tighten up the existing ones.

Only way oil can come out the ports is down the guides, and if the breather were blocked the engine might be trying to breathe via the guides.

Crankcase over-filled? Engine running on both cylinders?

[G-Man]

Good thoughts.

Just one more question from me. Is the oil clean?

If so I don;t think that it can be coming from the exhaust itself unless, as Nick said it is being forced down the guides.

I don't think that gaskets drying out is the issue. Also if you can get oil leaking from the exhausts then you would hear the exhaust gas leaking from the same place.

My money is on oil running down and forward from the plugs or cam cover(s)

I am often wrong, though..... :-)

I forgot to say - Beautiful restoration!


G

Crankcase breather plugged with something? Breather hose kinked closed?

Put some miles on it and see if the problem goes away (or have someone you trust take it for a few rides).

And yeah, maybe new exhaust gaskets would be a good idea, or seal up/tighten up the existing ones.

Only way oil can come out the ports is down the guides, and if the breather were blocked the engine might be trying to breathe via the guides.

Crankcase over-filled? Engine running on both cylinders?

[dragstart]

After a transmission rebuild, (just pulling the bottom of case), mine does the same thing. I didn't notice it leaking before. New exhaust copper, no exhaust leaks. I did overfill the oil level, thinking a dry engine may need a little extra. The oil level has dropped down to the first line on dipstick after 300 miles, so now I'm going to check breather tube, (it was open before rebuild), to make sure I didn't restrict it during reassembly. I'm leaning towards cam cover gasket as the source.

[dragstart]

After cleaning everything up really good, I took an easy five-miler from a cold start. Oil was coming from cam cover and migrating down the fins to the exhaust port area. As I prepared for battle with the cover screws, (PB Blaster, 40 taps on the head of each screw), I discovered that they were loose. WooHoo. Gasket looks good, I'm going to put a light coat of gasket compound on and put it back together.....................making sure the cover screws are tight. 99.99% sure that this is the cure.

BTW...........crankcase breather was fine, blew through the hose and had air out the oil fill tube, oil level in crankcase was just at top mark, exhaust has no leaks at port. Just trying to eliminate the other guesses.