Complete Rebuild - EC250

[RockefellerGG]

They were about 0.65-0.75mm higher, which makes sense. The band is angled.

[RockefellerGG]

The owner opted to go with it for now. If he doesn't like it, he can remove the head and do the mod later on.

[PEB]

ignition side crank seal looks to be installed inside out. I took apart a bottom end last that was last touched at the factory and the seal was opposite what you show here. Anyone care to chime in?

[RockefellerGG]

My GasGas manual stated the seal lip needs to face out. I've read of people seeing it reversed too.

[Jakobi]

Both of my main seals have been in the other way.

[barossi73]

Perhaps the translation was off.although i havent had my bottom end to bits,every other seal ive seen anywhere,ever,has lips to oil/inside,ie opposite to yours.wether it matters is another question!
If the lips taper either in/out in profile it would suggest theres a right/wrong way.
Only reason i can think of for that way is if crankcase press is negative, (vacuum).my 2t theory is a little rusty,is the crankcase pressure positive or negative?or fluctuating between?

[RockefellerGG]

I don't recall a taper to the seal. So the question is, do I flip that seal?

[Jakobi]

Crank case pulls charge in, and then blows it up the transfers, so pressures should be alternating in the cases. The seal will always seal better in one direction than the other - the logic is probably that by having it backwards as in the pic above, the better seal will occur in the direction it is facing, that being it may blow some oil/compression out past the seal, but be less likely to pull air/dirt past the seal into the engine.

Given it's already fitted I wouldn't bother changing it.

[barossi73]

I tend to agree,you will prob damage it removing it and need another one.which way was the old fitted when you removed it?
Shouldnt be too difficult to flip/replace later if it gives trouble

[RockefellerGG]

This is the picture I took removing it. I think I'll leave it the way it is. After the first run, I'll pull the ignition cover and check things out. Good catch, I'll edit/update the build step for others.