04 650v2 flame thrower

[mudthug]

got 04 650 (kawi engin) just lost all power and is shooting flames out of the rear carb and black smoke out tailpipe if i keep it pind its a auto had dose not have enoph power to move in h only in low seems like timing is of if it where single cil but i dont know with the twin any ideas

[Lélo]

I found a crack on the plastic bout beetween the cab & piston...
No more back fire & lose of power...