Topic: Oil Leak Help - 1978 CB750F

[cowboycletus]

Hey Guys. Looking for help diagnosing an oil leak. It drips badly while on the side stand and while riding but fortunately doesn’t seem to make it to the rear wheel, probably because my shoe catches most of it. I’ve already replaced the shift shaft seal and gear shifter cover gasket. I think it may be coming from the cover forward of the gear shift cover...I’m not sure what it’s called. Photo added for reference.

Thanks for the help!

[newday777]

That is the stator cover.

[754]

Dyno cover , mine looks same, has a crack where your arrow is pointing, common  for them to leak if they get dropped.

[bryanj]

Sometimes called generator cover in parts books

[nanahan]

BuY the NO LEAK Cycle X Dyno gasket, a little bit more expensive but worth it.


http://www.cyclexchange.net/Engine%20Parts%20(Non-Cafe-Gaskets).htm


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[cowboycletus]

Awesome. Thanks the help guys. I’ve got a new gasket on the way. We’ll see if that fixes the problem!

[754]

Well maybe you should also inspect the cover... mine has a crack there, ain't no gasket gonna fix it..

[madmtnmotors]

It also appears to have that deadly silicone oozing out from the gasket location. Do not use silicone upon reassembly and be sure to remove all traces of any silicone that had been used before. That stuff is notorious for finding its way to the oil jets in the head and starving the top end of oil. Not good...

[PeWe]

Also called Alternator cover.
You can remove that cover without much oil leak if you lean right side to a wall. 1st gear in just for sure.
Be aware of the wiring that comes out from it.

Good to have something beside where you can let it rest while preparing for new gasket. I like Honda gasket. NO sealer needed.

There us one thing inside you need to make sure to be reassambled properly, starter gear to motor pinion usually come loose when its pin also sit in the Alternator cover. There is a washer on that pin against cover.

I recently replaced the cover with generator windings on my K2. I removed the cover beside to easier connect everything.
You can see below how bike was parked. I think a tablespoon (or 2) of oil dropped out during this job.

The issue for you can be hard sitting Honda stock X screws in need of correct screwdriver bit, JIS 3. An inpact driver and heavy hammer might be needed too.

I have allen heads on my bikes.

[cowboycletus]

Thanks for the tips guys! I’ll be sure inspect the cover thoroughly. Hopefully it isn’t cracked and my leak can be fixed with a fresh gasket.

I’ve already taken the screws out of the cover once just to make sure I could. A #3 Phillips and a ratchet did the trick just fine.

[Jerry Rxman Griffin aka MuthaF'er]

Upgrade to a set of allen head bolts and a set of T Handles. You'll eventually be glad.

[Johnie]

Keep in mind there is a rubber gasket that seals the stator wires where they exit the stator cover. You'll see it when you remove it. If you don't want that to leak once you get it all together use some Permatex anaerobic gasket maker on that seal. Been there...

[PeWe]

I used the good smelling black/brown Permatex Aviation no 3 on that rubber wire seal/grommet

[cowboycletus]

New gasket came in today and replacing the old one was a cinch. I spent more time cleaning the old gasket off than doing anything else. It still leaks though. I did not put gasket maker around the plugs for the wires leaving the case. I was hoping to avoid using it but that may be my next step. The gasket I ordered (from Dime City Cycles) does seem very thin. Anybody have a good source for OE replacement gaskets? Not sure how much of a difference that will make.

Thanks guys!

[HondaMan]

New gasket came in today and replacing the old one was a cinch. I spent more time cleaning the old gasket off than doing anything else. It still leaks though. I did not put gasket maker around the plugs for the wires leaving the case. I was hoping to avoid using it but that may be my next step. The gasket I ordered (from Dime City Cycles) does seem very thin. Anybody have a good source for OE replacement gaskets? Not sure how much of a difference that will make.

Thanks guys!

I get nice individual gaskets from CB750Supply sometimes. If you can, get a tube of Hondabond #4 or else Permatex #2 (non-hardening type) sealant, use on one side of the gasket (the cover side). I'd suggest also getting the tranny cover gasket, for the following steps will require you remove it, too.

A question: is the bottom of the cover dented inward, like it fell over on that side once? This makes little cracks that weep oil through to (your and my) boot. If so: you will need to remove the alternator windings to get to it for a repair patch. To do this, you must remove the tranny cover so you can disconnect the plugs to take the alternator/cover to your workbench. Otherwise, all the twisting and bending of the rubber grommet will destroy it, and they are not available that I know of...

Then remove the alternator windings, clean the bottom of the case with gasoline first and maybe lacquer thinner next, let dry a while and smear mixed JB Weld Aluminum over the bumped-in area. Then let it set for at least 4 hours and reassemble.

I would estimate that fully 70% of the engines I see for rebuild have this done to them nowadays. Even my own took a tumble on that side when someone (drunk) tried to park too close to my bike, which was in the center of its parking spot, and knocked it over.    And, it has JB Weld Aluminum there, from 1980...

[754]

I had mentioned to him that it may well be cracked there,  hoping won't fix it.
 Mine is cracked right where he is pointing to. I did not see it when I put that motor in and it did not leak there., but now I can see a small crack.

[MRieck]

Most of those leaks I have seen come from the stator/field coil rubber "grommets". The cover gets taken off and that seal is gone. Plus the grommets start to split etc after 50 years. You have to use some good oil resistant silicone sealer between the grommets themselves and the cut outs on the alt cover and engines case. Degrease thoroughly first. I put some around the outside of the grommets too after the alt cover is bolted in place. I have never had a leak after that with 750's and early Kawasaki Z's