Mystery oil leak 650G

[kerrfunk]

Hey gang

Sometimes it's been heavy -- leaves a few drops of oil on the floor -- but most of the time it only drips a bit during a ride.
Sometimes the ride dripping is heavy and my right leg gets pretty oily.
Sometimes there's hardly anything.
It's been a bother for oh, at least six months or so.

So last week before I went for a ride, I shoved cottonballs into the fins, to see if I could find the source.

Bingo. Top fin.

But what is the problem? What do I do now?

[Redman]

Good technique ... !

Not any oil above that? (say, from cam end plug)

Not any oil forward of that ?

If not, well, then: head gasket.

[Steve]

Have not seen cotton balls used before.

The usual method is to clean the engine as well as you can. Spray some degreaser all over, especially your now-suspect area. When it is dry, spray on some foot powder, then go for a ride. Check every couple of minutes, you should soon see where the powder is discoloring, indicating the source of the leak.

When you see leakage at the top fin area, the immediate guess is whatever is directly above it (head gasket), but there is also a remote possiblity that it might be as far away as the cam chain tensioner, and is being blown over to the end of the block. The air currents in that area do some strange things, and it's worth checking before you start tearing the engine apart.

.

[kerrfunk]

Perhaps tomorrow I'll replace the cotton balls and head up, see if there's anything thataway.

[2BRacing]

One of the regular maintenance checks is to re-torque the cylinder head nuts. When I had an oil leak on the opposite side to yours, I found that the nuts were too loose, because I had never checked them.

After re-torqueing to the correct spec, no more oil leak!

[themess]

GS650Gs had a problem with sealing the cylinders to the base. Pulling the engine, removing the cylinders and replacing the gaskets was necessary. It happened to my '82. I hope you're luckier than I was.

[themess]

Oil Testing question

Recommended oil change intervals for motorcycles are far less than for cars. For air cooled machine, this makes a lot of sense. But what about water cooled machines? Oil in those engines should last as long as oil in cars, I would think.

But....

Motorcycles rev up much higher than car engines. Does this hurt oil?

Most motorcycle gear boxes are lubricated with engine oil. Does this hurt oil more than the engine does?

I've sent oil from my car to Blackstone Labs for analysis, and I'm sure they'd be happy to test oil from my Wee Strom for the same fee. Would their testing show if the factory recommended oil change intervals are significantly too short?

[Brendan W]

Aside from double checking the tacho drive and the top of the chain tunnel..............
With the bike warmed up and idling get a torch and see if you can see oil weeping from the headgasket anywhere on that side of the motor.

[Rich82GS750TZ]

?..... get a torch and see if you can see oil weeping...

That's a cultural English word usage difference that could really get someone in trouble.

UK-Torch = US- Flashlight

US-torch usually refers to a flame with a gas source. Something like this.
IMG_0226.JPG

[kerrfunk]

So there's some more info, and I think it's a question of improper torque on those bolts.

I have some highway pegs attached to my engine guards, and I noticed two things today:
One, when I had my feet on the pegs today, the oil light turned on.
Two, when I had my feet on the pegs today, the engine slowed suddenly, sputtered and backfired.
This was a repeatable thing.

And when I pulled the pegs towards me today, the oil light turned off.

[Brendan W]

The obvious one is what is your ignition pickup lead doing down there behind the pegs?
Have you got some Evel Knievel trouser leg flapping on the oil pressure wire?
Do I see a missing bolt on the bar attachment to the frame?
Is the motor grounded ok.
Had any starter/cranking issues lately?
Whatever you do don't go looking with a torch