Compression

[DuctTapedGoat]

So I'm out riding Thursday and I feel a loss in compression, felt like an immediate drop in performance 50%.

So I finish the ride home and check:
Seals appear fine.
Gaskets appear fine.
Rings appear fine.
Now it won't start.

What else could cause a drop in compression, when I roll the bike around without clutching I can hear something breathing and there's little resistance.

I have new seals on the way anyways, but what else could it be.

 

[DuctTapedGoat]

Well even though my head gasket appeared 100% fine I changed it out and it fired up. I almost gave it vapor lock.

I have an extra motor around, so I have rings and ordered seals anyways for my road side emergency kit.