Don't look at me, I presume a previous owner did this. Certainly wouldn't happen at the factory.

Depends on what model and year?

Looks right for a 250/360/400.

74 DT360A. In this orientation it has the teflon lip on the wet side and the rubber lip on the dry side, seems backwards. The spare 360 motor I have has the seal installed in the other direction as well.

I'm pretty sure it's backwards. Would be somewhat difficult to even install in this orientation.

There are so many different variations on the subject.. that I would have to narrow it down to:
Rule of Thumb:
Stator side Spring inside -
Clutch side Spring outside -

Ummm... if you absolutely know it's wrong, why ask?

Fact is many... if not all... of the correct original crank seals for the 250/360/400's have "castle turret" bumps on one side of the seal to prevent it from being pressed in too far and completely cutting off the flow of oil to the outside of the main bearing.

Factory seals are true dual-lip, dual-spring on your bike. Type SW. I can't recall seeing an SW where one lip was teflon and the other rubber? That doesn't make sense for a true dual lip seal..



Correct seals can be hard to find for some models so many people are selling inferior single lip seals with a non-spring loaded "dust seal" as the second lip. They will work... Yamaha used that type on the ignition side 125/175 Enduro from the factory. But they are not as good as a true dual lip seal. (I use the 77-79 IT175 ignition side crank seal on my 175's... true dual lip-dual spring)

This is the stator side seal out of my spare dt360a motor. Looks like teflon on what I would call the outside lip.

I never said I knew which orientation was correct, let alone with any degree of certainty. If the inner lip is doing its job though, the outer lip will see minimal lubrication. Teflon makes sense here.

I can't tell you what that stuff on the seal is... I can tell you with certainty, the side showing in your picture... what I call the "castle turret" side... faces in towards the ball bearing.

If I remember correctly the major reasons for special materials used on crank seal lips is not as much "friction" as it's "heat and chemical resistance".