Just got from a friend of mine, has been sitting for two years, cleaned carb and flushed tank, got running, when revvin up it spits out lots of black smoke and back fires as it slows down what can I do

 

Welcome to the club. I've got a 85 250es BigRed that is the bomb. No complaints...Where's the Mud![img]i/expressions/face-icon-small-smile.gif[/img][img]i/expressions/face-icon-small-wink.gif[/img][img]i/expressions/face-icon-small-sad.gif[/img][img]i/expressions/face-icon-small-blush.gif[/img]

 

Have you checked out the piston/ring?

 

my big red is doing the same thing do a compreson test it sould be about 160 psi i need rings for mine