Hi I just bought an SP MC21 engine which has been sat for a good while.
Both crank cases have gearbox oil in them(it was sat on the floor with no front end in the bike or rear wheel).
My thinking is that both the RH and centre crank seals are gone allowing the oil to seep through. Oddly there is no leakage by the generator)
Replacing the end seals is no issue but the centre one is.
Does any one know if the seal in the centre bearing would 'weep' over time if they were immersed in oil.
As the seal is not like a conventional seal I guess it might only seal properly while it is rotating.

Any advice or thoughts would be good.

Cheers

I think they do leak a bit over time yes. Whether they should or not is a different matter, but the seal will have dried out over the last 17-20 years.

I'd do a compression and leak down check, but budget for a new centre bearing seal and you may as well throw a new bearing set in while you're at it...

You can't do just a centre seal, Dave, and it's very rarely just an issue with the centre O-ring (that sits around the outside of the centre main).

The simple answer is "no, they shouldn't leak across the centre bearing", but you may get away with a very slight leak across it for a short time. It will only deteriorate though, so budget on a new/replacement crank/rebuild in the near future.

When doing a leakdown test, it's not uncommon to see the seal hold [more] pressure one way than the other. There are countless threads on testing the seal on the forum... both pressurised (as it should be done) and unpressurised. Have a read of other people's findings, but as I say, it shouldn't leak at all. Any leak is detrimental to performance.
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Andy.
NSR-WORLD.COM

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Thanks for the advice guys, looks like I will be getting a new crank then.