GS750 Stationary oil leak

[Mary Hinge]

Before I start taking things apart I'm hoping one of you Guys with far more GS experience than me could point me in the right direction please. If I put the bike on it's side stand oil will drip from under the generator cover but it doesn't leak whilst riding. I've checked the oil level and it's not overfilled

Thanks

[Rijko]

On the side stand the bike is tilted to the left, so oil will migrate there.
Could be the generator cover gasket is leaky, but not necessarily.
Could be from the tacho connection on the cylinder head, valve cover leak, head gasket leak, etc. etc.

Best advice is to clean the engine well and look for fresh oil seeping out somewhere.

[Mary Hinge]

Sorry, should have said that there's not a sign of oil or oil leaking anywhere else on the motor.

[bonanzadave]

Sorry, should have said that there's not a sign of oil or oil leaking anywhere else on the motor.

If you're positive about that then maybe its under the motor. Check the oil drain plug (crush gasket) and the pan gasket.

[bwringer]

A few other possibilities that come to mind...

1) The o-ring around the gear position switch.
Here's a shot of the underbelly of a junked GS850 engine. The gear position switch is that round brownish gadget on the right with a wire coming out of it. This o-ring is undoubtedly glass-hard and cracked if you haven't replaced it in the last 40 years.



You'll note that the photo mentions the Mystery Hole; this is the bottom side of what is basically a drain hole under the starter, needed so that the starter cavity doesn't collect water and drown the starter motor. Here's the top side with the starter removed. That blue tubing is only stuck in there to show the connection:


There's an empty chamber in the castings that connects the two holes.

2) So another common source of leakage is the o-ring around the nose of the starter. Oil can make its way from there into the Mystery Hole cavity, then collect in there and drop out when you park the bike on the side stand. This o-ring goes glass-hard and cracks after 40 years of heat cycling, but is easy to replace.

The same goes for other oil leaks from the back side of the engine; the oil can make its way into the starter cavity and out the Mystery Hole.

3) One very common source is the cam chain tensioner; the seal fails and drips oil.

4) Less common is the o-ring around the oil pressure switch.

5) You can also end up with oil here if the stator wires are poorly sealed.

FWIW, here are my detailed instructions for rebuilding and resealing the cam chain tensioner to fix this leak. If you haven't done this, you probably need to.

https://www.bwringer.com/gs/camchaintens.html

[tom203]

The easy thing first to do is replace the stator cover gasket...a lower bolt might have loosened up just enough to drip when on side stand . Get a genuine Suzuki gasket and avoid the cheapies!

[Mary Hinge]

Thanks for the advice Guys, much appreciated 👍

[fast eddie 52]

If it's just a few drops, I find it easier just to put some cardboard or drip pan under it and wipe with a rag from time to time...more riding, less wrenching...

[Rob S.]

If it's just a few drops, I find it easier just to put some cardboard or drip pan under it and wipe with a rag from time to time...more riding, less wrenching...

Exactly - it's not leaking oil, it's sweating horsepower.

[Mary Hinge]

The easy thing first to do is replace the stator cover gasket...a lower bolt might have loosened up just enough to drip when on side stand . Get a genuine Suzuki gasket and avoid the cheapies!

Hopefully going to have time to get into this now and check through all of the suggestions made. I've ordered a new genuine gasket to replace that because with it being damp already who knows. Does the rubber grommet that holds the wires need any special attention/sealing ?

[bwringer]

Does the rubber grommet that holds the wires need any special attention/sealing ?

Yes, just a LIGHT smear of RTV, or case sealer would be better if you have some.

[tom203]

Some of cover bolts might be different lengths....best to make cardboard template to mark/hold them during removal so you can reinstall in correct spot...otherwise a long bolt in shallow hole might bottom out without squeezing gasket

[tatu]

It is probably leaking all the time, just when it's standing the oil isn't being blown away.

[Brendan W]

Some of cover bolts might be different lengths....best to make cardboard template to mark/hold them during removal so you can reinstall in correct spot...otherwise a long bolt in shallow hole might bottom out without squeezing gasket

Seen that once or twice. Someone had fitted a 40mm screw in place of a 35mm. The long screw seated against the cover but had bottomed out before squeezing the gasket. Another time someone had cut long screws but left them a bit too long.
As far as I know the three lowest screws on the 750 generator cover are 35mm but there are 40s and 45s there as well that could easily get mixed up.

[Rich82GS750TZ]

If you get the bolts mixed up you can look at the parts fiche. The length of each bolt is in the part number.