Vintage and Classic Hondas

Oil on the exhaust tip

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Cabreco

Oil on the exhaust tip

Today I noticed that the left side exhaust tip was slightly damp with black oil. (nothing huge) The right one is clean. There is no smoke or burning smell either. The oil in the crank case is golden color. There is no visible sign or feel in loss of power like with a blown head gasket. I haven't done a compression test yet but my 1st inclination would be a blown oil retention ring on one of the pistons or possibly oil seeping past the valve seal. I did take note that the left side outside exhaust pipe at the flange was cooler than the rest.

With the exception of this oil dampness, she is running great with plenty of power.
What do you guys think, am I ok as long as I watch the oil consumption or am I heading for a major problem?

FIONA
1981 CB750K

Andy
Tennessee

LukeM

Re: Oil on the exhaust tip

Administrator

Pull the plug on the suspected cylinder, and see what's happening there.
I think there's a resource or two on the web that details plug appearance and what can cause that. I just don't know where at this point in time.

Compression check would be a good thing as well.

Luke M

Used to have a 1979 CB750L, sold it as a parts bike, now riding a slightly modified 1984 VT700C. Network/Field Engineer. Central OH, USA, Earth, Sol System, Milky Way Galaxy, Universe.

TOOLS1

Re: Oil on the exhaust tip

Administrator

Ditto, what Luke said.
TOOLS

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1976 CB 750-A X 2
1977 CB 750-A X 4
1977 CB 750-K
1976 CB 750 F
1981 CB 750
1966 Kawasaki SG 250
1981 KZ 750 LTD
1973 CB 350
1979 CM 185 Twinstar
1982 Honda XL 80
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Cabreco

Re: Oil on the exhaust tip

I'll pull the plugs in the morning to see what's going on.
The thing that puzzles me is the oil at the exhaust end is black, the oil in the crank case is gold. The bike isn't smoking so it would lead me to believe that if it's a valve guide seal it must be the exhaust valve, and it's not being ignited.
So...I'm wondering if the oil that the PO put in was automotive oil and a thinner viscosity, then if the seals are weak the oil would seep.
Still the bike is running strong!

FIONA
1981 CB750K

Andy
Tennessee

Re-run

Re: Oil on the exhaust tip

Administrator

Are you sure it is oil? Maybe carbon that is dripping from condensation in the pipe?
The PO may have put oil in the pipes to prevent rot on the inside.

The ride IS the adventure. The destination is just to get gas!