blown piston?

[99 shee]

I went riding today and notice that the Banshee was not running right.I pulled the plug from the right side cylinder and there was blackish grey sludge on the plug. when it's running ,the exhaust on the right side is very weak. I'm wondering if I may have blown the piston. I put new plugs in and had the same problem.I run a foam filter with no air box and may have gotten some water in there. any idea what I may have done? Thanks

[sprinklerman]

Do a compression test. If it reads good  , then look through the exhaust port for signs of damage. Look through the intake port for damage.