Cracked Piston?

[Exrider434]

I'm workin on my buddy's yfz and yesterday i came across a cracked piston, the crack goes across the top of the piston then down the side to the wrist pin. When it cracked it also cracked a ring and made the quad lose all compression. The valves look fine. they dont look like they were hit or anything.. What woulda caused the piston to crack like this?

[250r4life]

its a freak thing... my buddies did the same thing last march...

[Ride1Rob]

Running a bike too lean and to much time on the topend can cause this. I've also had problems with 2 of my JE pistons doing this as well. Certain performance pistons aren't very durable over time. I'm more than sure that it's one of the 3 why this has happened.

[Exrider434]

So do you think i would be ok to just hone the cylinder and replace the piston and rings?

[Ride1Rob]

It depends on how damaged the cylinder is. How much scarring does it have? If it's minimal I think you would be okay to do so.

[Exrider434]

Well i took it and got it honed and 2 shops told me that the cylinder looked great for an 04 that toasted a piston and it didnt need bored or anything.