Is there supposed to be oil in the left crankcase cover?

[wilkin250r]

Is there supposed to be oil in the left crankcase cover, with the stator? I know there isn't any oil in my 250r, but there appears to be in my 250X.

The repair manual doesn't give me a specific answer, but it DOES list oil seals in the cover for the shifter shaft. Also, the repair manual says to drain the oil before removing the left crankcase cover. Why would there be oil seals, and directions to drain the oil, if there wasn't supposed to be any in that area.

But at the same time, why in the world is there oil in that area?

[F-16Guy]

Yeah, the 400ex is the same way. I think I would rather have it in an oil bath. I just took the stator cover off of my CR250, and the flywheel and everything else is pretty rusty.

[wilkin250r]

Well, that's a relief. I know my 250r pretty well, but I don't know the details on this little 250X. I was thinking I needed a bottom-end rebuild. As it looks, I think I can get away with a simple top-end.

[YZ400EX]

yea the 250x's have oil on the flywheel side..even though there is an oil seal on the crankshaft under the flywheel, there are small holes in the case itself to let the oil flow in..Thats why if you bust a stator cover on those things it sucks so bad because you keep losing all your oil!! Someone needs to design a case saver for the 250x/300ex..

[UglyMotha™]

boy ain't this a change, wilkin's asking the questions now :p

[wilkin250r]

Originally posted by UglyMotha™
boy ain't this a change, wilkin's asking the questions now :p

My knowledge of engine theory and physics is top-notch. But I've never taken this engine apart, so I don't know the specifics.

I got more questions, LOTS more. Like this stupid head gasket. Any time I've ever done a rebuild (like my 250r), I always had a gasket specifically matched and designed for my rebuild. But now, I've got a stock head gasket, but my bore is 2mm larger. What do I do? Am I supposed to trim the headgasket to match my bore size? How do I trim it?

[UglyMotha™]

i'm 99% positive you can use the stock head gastet on a 2mm over bore, but most engine builders to offer head gaskets to match the different bores, and some do bore stock head gaskets but truthfully i really dunno how they go about it

[wilkin250r]

But wouldn't that put the edges of the gasket INSIDE my combustion chamber? Wouldn't that be an issue?

[UglyMotha™]

yah, but i guess its really not an issue if it doesn't touch the piston, i guess there really not that much hanging into the cylinder, when i had the 416 you just use a stock head gasekt

[300exOH]

By having the gasket in the combustion chamber you are only losing a little volume which increases compression a little.

[wilkin250r]

I'm not worried about compression. I'm worried about having the gasket directly exposed to the flame front, and possibly burning or flaking off and rattling around inside my cylinder.

When the gasket is between the head and jug, it's not a problem. You only have a very small surface exposed to the flame. However, when you have the gasket material actually extending INTO the combustion chamber, that CAN'T be good, I would think. Is it really not an issue?

[UglyMotha™]

I haven't had a problem with the 416 and neither has any other joe that i'm aware of

[300exOH]

Sorry I was kind of joking about the compression. Any increase would be minor. I've never heard of anyone ordering gaskets for overbored cylinders though. I'd wouldn't buy a cheap gasket just to be safe. I'm in no way an expert on the subject though.

[wilkin250r]

Originally posted by 300exOH
I've never heard of anyone ordering gaskets for overbored cylinders though. I'd wouldn't buy a cheap gasket just to be safe. I'm in no way an expert on the subject though.

Maybe that's the real issue, then. Perhaps I should talk to an expert about it. Maybe it's not an issue, but then again, it seems unfathomable to me that you would leave your gasket extending directly into your combustion chamber.

[UglyMotha™]

why is that, i'm telling you any 416 kit your order comes with a stock headgasket even from reputable engine builders, there's only 1mm of gasket hanging in the cylinder and it doesn't affect anything i ran mine for 2 years with no problems didn't pop a single head gasket, and i'm assuming you had the 250x bored 80 over

[wilkin250r]

I'm not calling you a liar. It's just so contrary to to my knowledge and logic, and thus I would like to hear it from a few different sources.

[MIKE400EX]

Might work if you're lucky, but the head gasket should never protrude into the chamber (smaller than the actual cyl. bore). It can quickly lead to a hot spot and detonation before it burns and leaks, among also the reasons you mentioned. Cometic probably makes an overbore gasket. If not than you can sandwich the gasket between two plates and turn or mill it larger. If you're careful (and it's a metal gasket), you can glue it to a plate with some contact/rubber cement and cut it with one of those cheap adjustable sheet metal hole cutters. A little solvent and the glue will clean up.
Best case is flush to very slightly larger with a very smooth inside surface.