ORIGINAL: Uberchav Alex
Take the crank out and hold the engine up to the light, look through from the rear and if it looks like this, then it's screwed.
Well as a lot of engines use a metal shielded front bearing instead of a rubber sealed (on one side) which have a bigger gap than the shot rubber one you've shown, I think my all over the place experience of 26 years of model engines explanation is pretty spot on...
Although some engines do use a spiral on the crank rather than primary compression in the crankcase...
