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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