Was driving my o6 kx 85 . was at full speed and it cut out and refused to start and when i try to start it , it would backfire i think its getting a spark but no starting . does anyone know what the problem may be ?

Hmm sounds terminal matey, im afraid to say. IF you were riding flat out and it just cut out and rolled to a stop. Did it give any hesitation just before it cut out ? Was there any difference in engine note before or during the cut out ?

I'd rip the barrel off and check that you aint scored the bore. Check the rings, plug etc. But in most of the 'blows' we have had this backfire is common place. 4 of our engines did this and it was the crank bearings that had gone. Crankshaft had just enough movement to pivot on its axis which in turn nipped the barrel and caused a split second sieze. Result bottom end build, barrel hone, new piston, rings and gasket set.

Hope this helps mate.

Mista B. Hmm sounds terminal matey, im afraid to say. IF you were riding flat out and it just cut out and rolled to a stop. Did it give any hesitation just before it cut out ? Was there any difference in engine note before or during the cut out ? I'd rip the barrel off and check that you aint scored the bore. Check the rings, plug etc. But in most of the 'blows' we have had this backfire is common place. 4 of our engines did this and it was the crank bearings that had gone. Crankshaft had just enough movement to pivot on its axis which in turn nipped the barrel and caused a split second sieze. Result bottom end build, barrel hone, new piston, rings and gasket set. Hope this helps mate. Mista B.