Hey, I have a 1985 Suzuki LT250R that I have recently rebuilt the engine on. It has recently had the cylinder bored 40 over to 71 mm and new rings and piston. I completely tore it all down and cleaned it. I am running it at a 32:1 fuel ratio. The spark plug is still good. It has a K&N Universal Coned Air Filter. I took it out for a ride and after about 30 mins of riding, it poped and blew white smoke out the airfilter and wanted to quit. Everytime I tried to rev it up it would pop and try to die. Then when we got it back to the shop I would start it up and let it idle and it would pur like it was brand new for about 30 secs to a minute then just abruptly die. The exhaust smelt different. The smell resembled the smell of starter fluid. (Of course it wasn't that. That was just a description of what it smelt like.) If anyone knows what could possibly be wrong or have any ideas, ur feedback is well appreciated. Thank you.