my nephew got a predator 90. It runs fine but really lay down a smokescreen. I've heard crank seal or too much oil from pump. If it was wore piston rings would it still run fine? Thanks if anybody can lead me in rite direction

 

I'd take the exhaust pipe off and soak it in kerosene or naptha for a few days.You'd be surprised how much oily residue these 2 stroke pipes and mufflers accumulate over the years. I'd get a new head pipe gasket if you do and also check for any carbon build up around the exhaust port.I've had to chip out chunks before. Pumps were pretty much set at the factory. If it's running ok,then the pipe is all I'd mess with.

 

I heat the pipes up red hot and blow compressed air thru them to clean.
If you do this, be careful! It'll throw flames.

 

If you're running really rich (black plug) or real cheap oil you can get a mosquito killer as well...