First top end rebuild, I have a couple questions, Tri-Z 250

[King Trikester]

I pick up a decent 1986 Tri-Z with a blown top end the other day, I finally tore into it and was surprised at how bad the piston a cylinder are scored. 195416

I'm wondering what happened to cause this much damage? The back side of the piston looks brand new, as well as the rings, and you can see the damage to the front side, nothing left of the rings and a badly scored piston. Any ideas of what caused this?

I can't find a downloadable manual, the link from this site fails to load, any one have a link?

Next is the crank shaft, it has a bit of play from side to side, how much is ok?

[DohcBikes]

Your link doesnt work, but it sounds like a classic case of being ran with no air filter in the dirt or sand so far.

[King Trikester]

Ok I fixed the link, and now that you say that there was dirt on the inside tube after the air filter, it looked someone hit a mud puddle and got really dirty water in the intake, the air filter is spotless but everything else covered in dirt.

[Bren_downe]

Gasket leak. It sucks air in on one side "leaning" it out while the other side gets proper lubrication.
My Fooler had a base gasket leak just below the exhaust, I thought it was 2 stroke pipe spoodge and ran it.
This is what my piston looked like.
195417