Topic: Cracked stator cover...oil pouring out..help?

[Dexter McHaze]

Hi all. I've lurked here for some time but haven't posted before. Love the community here! Unfortunately I'm posting now because I'm really concerned about my k8. It got knocked over today and the stator cover now has about a 2 inch crack in it. It's pouring oil. My biggest concern is why there is a steady flow of oil coming from inside the stator. Im pretty much a novice with motorcycle mechanics but oil streaming out of a stator cover really raises some concerns for me. Is this typical or could there be major damage under the cover causing this leak? Once the bike cooled off it slowed to a slow drip but when running it starts streaming out pretty quick. Obviously I'm not running it much with all the oil leaking out but just trying to check the severity of the leak.

Any thought or insight would be greatly appreciated. Thanks!

[Elkie]

Oil shouldn't be in there. Take the cover off and see whats wrong.

[Johnie]

Welcome to the Board Dex!!!  There is a small amount of oil behind the stator cover of the 69-76 CB750. I am not an expert on the K8, but you will get some confirmation here from the other guys just to be sure. My first thought is oil belongs there on your bike, but let the K8 guys confirm that. If the bike just tipped over I would think you only cracked the cover and did not do any further damage inside. Since there is no pressure behind the stator cover, some guys have used JB Weld to fix those cracks. You could have it welded, but it depends on if you want to see the fix or not. Might be easier to just go buy another cover on eBay which is what I would do. I would just hate to be driving down the road and have the fixed stator cover start leaking. Then you really have a problem...especially if you did not see the oil light come on while tooling down the highway.

[Bodi]

The 750 alternator is not sealed but oil shouldn't "pour out". I'm not an expert (at all) on the bastard stepchild 77/78 engines though.
There's no oil seal at the alternator end of the crank and that main bearing's oil (pressure fed from the pump, so there will be a fair bit) dribbles out of both ends of the bearing.... whatever dribbles from the alternator end drains back down to the sump through the alternator area. It never fills up unless the drain hole is plugged, and the sump oil level is very low indeed (since the "dry" sump scavenger pump picks it up about 1/2 inch above the bottom of the sump).
If your crack is right at the bottom of the cover then it will naturally dribble out there a bit.
There's no pressure there so just giving it a good cleaning (remove the coils and run it through a dishwasher? Or brake cleaner liberally applied in and around the crack?) and patching with JB Weld or similar should be sufficient.
If the cover is damaged enough to shift the coil positions you will be in trouble. Check the rotor inside and outside surfaces for new wear marks. Shiny scratches mean the rotor is hitting a coil part. New cover time probably.

[eurban]

Yes, all SOHC 750s will and are supposed to have oil behind the stator cover.  There is nothing unusual about the late engines in this regard . . . . Most likely you have nothing wrong more than the obvious cracked cover.  I would replace rather than repair but both are viable options.  

[Dexter McHaze]

Awesome! Thanks for the replies. I haven't had time to remove the cover yet but I going to try tonight. This puts my mind at ease however. I should have clarified that oil was pouring out when the bike was hot and running on the kickstand. So it was leaning over to the left, probably causing a bit more oil to pool by the crack in the cover. I have another cover on order and will be jb'n it in the meantime. Thanks again everyone!

[MCRider]

Yes there is oil in that cover. Yes the alternator is bathed in oil. It is flung around by the crank to lubricate the starter parts, and it doesn't hurt the alternator. While on the one hand there is "not much" oil there, any amount of oil is alot and it will leak like a stuck pig if that cover is cracked.  

There is a drain in the bottom of the cases that allows the oil to run back into the sump, assuming its not coming out a crack instead.

When removing that cover, put the bike on the centerstand. Put a small shim under the foot pedal of the centerstand to make it lean slightly to the right. That will allow the oil in the cover to run down the drain hole and not on the floor when you pull the cover. Put a pan under it any way to catch the drippings.

The cover has a gasket which will likely rip when you pull the cover so you may want to have a new one handy.

I'm thinking you have to pull the transmission cover too to get to the wires you'll need to unplug to get the alternator cover completely off. Maybe not, but if so it has a gasket too.

Maybe someone can help out on that.

[I Zombie]

I just had mine welded up. Yes you have to pull both covers & the shifter arm. Shouldn't have to worry about the oil seen most of it that was gonna leak out already has. It's a pretty simple off & on swap once it's be tig'd back together.

[MCRider]

Thot so, thanks!

[mystic_1]

Behind the alternator cover on the upper edge of the gasket surface of the crankcase, you'll find a plug that seals off the left side of the main oil gallery, which is under direct full pressure from the oil pump.  If hte alternator cover is damaged badly enough to allow this plug to pop out, you'll get a gusher.

On the other hand, if you're running the bike on the kickstand, oil will pool in the left side of the motor because of the tilt.

If you put the bike up on the centerstand, what happens to the flow volume?

Just throwing out possibilities.

mystic_1