Countershaft Seal

[i_wheelie_longer]

So I did my first bottom end rebuild on my YZ250 and everything went great (new crank, crank bearings, and crank seals). Since I had it apart I put in a new piston as well since I had 21 hours on my previous piston. The bike fired up on the second kick, and saw no leaks between the cases, etc.

I rode it up and down my street a few times to check that everything worked smoothly. When I got back I looked for leaks again and saw oil pouring out of the countershaft seal. I had replaced this seal as good measure, so obviously I did not install it correctly. I applied grease around the outside of the seal and pressed it in with my fingers and used a socket to lightly tap around its perimeter to seat the seal into the case.

Do I need to press the seal in further? It is flush with the outer case and that's how the old one was, but do I really need to pound this new one in? Any suggestions? Or do I just go ahead and buy a new seal?

[Yamaguy55]

Put another one in, dry this time, and check to see if your transmission vent is kinked or clogged. Generally, flush is correct. I never lube them up, I want them to grip the case. The sealing lips get moly grease.

[Greg Y]

Isnt there a seal inside the case too.....an oring under the bearing under the sprocket bushing deal.

[Yamaguy55]

Look at the parts lists: there is often an O'ring inboard of the collar that the seals goes against, the one that the sprocket fits against.

[i_wheelie_longer]

All of the parts diagrams I see only show the seal, then sprocket, then lock tab, then nut.

Would you guys mind showing me a diagram of what you are referring to? Thanks.

The bike is a 2005 YZ250

[Yamaguy55]

You didn't specify the year, so I picked a 2005. Item 27 on diagram. It probably goes between the collar and the bearing, it would have no value where they show it. Look in the the service manual for more info.

http://parts.yamaha-motor.com/partimage.gifx?d=120934,2,0,sport

[Greg Y]

that o ring is there on all of them.