Crank Seal Question

So, I've searched and I'm somewhat confused...

2003 RM250

I replaced the clutch side crank seal and now it leaks even worse. I put it in spring side out, per manual. The ID seems too big for the shaft, though I read on some threads that the seal seals against the gear. I don't see how that is possible.

Should the seal be against the gear on the 2003 rm250? or does it seal against the shaft?

How far in does the seal go? What should I use to press it in?

Should I put grease on the inside of the seal?

On the outside RTV? or Loctite?

Any obvious step I might have missed?

I used a Winderosa seal from WPS.



you put the seal in backwards.

According to the manual, and what I've read here, and the way the old seal was installed, I did not put it in backwards.

I have never seen a lip seal go in spring side out. But I have also never replaced the clutch side crank seal on a 03 rm250. The spring side should always point towards the fluid you are trying to retain(thats how it works.). And again this is just non make specific general info but the seal is usually meant to sit flush with the case unless otherwise stated in your manual. You can use damn near anything to drive it in. I like using drift punchs, and taking it slow.

Yes, you should put it in as per the manual.

However, are you absolutely certain your motor is an 03 and the seal you were supplied is also for an 03? The reason I say this is that for 03 they changed the seal, the 03 one having a smaller internal diameter than the earlier ones. They also changed the primary drive gear appropriately.

I believe the 2002 seal is 38x52x8 part number 09283-38021, while the 2003 one is 28mm ID (presumably 28x52x8) part number 09283-28024. Your apparently too big seal could well result from trying to fit a 2002 seal to a 2003 motor therefore.

On the 2003 rm250,

Is the seal supposed to seal against the gear or shaft?

I thought that the seal runs on the 28mm surface on the back of the gear. When yours is assembled can you actually see the crank at that point?

Spring out (keeps trans oil in the tranny, think about it).

Lip on the surface of the crank gear (can't really mess this up, it only goes on one way).

Should be no reason why a new seal would leak unless its the wrong seal. That was a good point by tim2007.

Crank seal on the stator (left side) side goes spring in (toward the crank shaft).

That actually makes alot of sense. So the clutch side seal keeps the gear case oil out of the crankcase with spring facing out, and the mag side seal keeps the 2 stroke oil in the case with the spring facing in. So does this mean that you usually leak a little 2stroke oil into the gear case? It doesn't seem like a lip seal can seal backwards.

Yamaha for sure uses a double lip seal on the right crank side and I wish Suzuki used the same seal set up. However, I do see more right seals fail on the Suzuki. Be nice if we could figure out what year model Yamaha crank seal that would cross over to interchange in our suzuki's.

As for crank pressure leaking into our tranny side, I am sure there is a small amount in the upper rpm passing by the seal, but I didn't design the set up so I don't really know the facts of why it is a single lip seal.

as an fyi...

I first used the WPS (windoerosa) seal and it was a single lip seal,

I have since replaced it with a ProX Seal which is a double lip seal. It looks to sit nicely, though I haven't ridden it yet.

I'll let you know...

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