Vintage and Classic Hondas

Oil Leak apparently from oil drain bolt

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Ken

Oil Leak apparently from oil drain bolt

Hi,
I just bought a 1980 honda cb 750 custom. And I drove it back from Indiana to NY. (~750 miles) The guy I bought it from just replaced the oil before I picked up the bike.

After about 600 miles I noticed a drop or two of clean oil dripping from what looks like the oil drain bolt.
(That's where the drops are and there is nothing else wet around it.)

I checked the bolt, though, and it's tight.

The bike drips about five or six drops per day.

Any clues as to what it might be.

Since the oil level window is still full, I thought that maybe he had overfilled it.
What would happen as a resuslt of that?

Thanks

TOOLS1

Re: Oil Leak apparently from oil drain bolt

Administrator

Welcome to the forum. If it was overfilled it would blow oil out the breather. My guess is that the gasket on the drain plug is bad. Where in IN did you get the bike?
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
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LukeM

Re: Oil Leak apparently from oil drain bolt

Administrator

Assuming it's really coming from the oil drain bolt, it probably needs a new oil drain bolt washer. According to bikebandit.com that's a 14mm drain washer. Probably aluminum. It's meant to crush just a little. When they use it on Asian cars, they need to be replaced when worn. I'm guessing yours needs to be replaced. If that doesn't fix it, the next thing to check would be the area around the drain. Hopefully it's not an issue with the threads. That can be fixed with a heli-coil-style insert.

Fairly cheap, even from the dealer man.
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.

Lucky 1

Re: Oil Leak apparently from oil drain bolt

What usually happens to beginners is that while they change the oil the washer drops
into the oil pan, then they put the bolt back in not realizing the aluminum washer is missing.
Then when they put the bolt back it and tighten it, it strips the threads because the bolt is not threaded
far enough without the washer.

be very careful when you remove the bolt.

Look to see if it has a washer.

On a Roadstar Adventure.