jagfixer

ok so i swapt my fan cooled motor with a free air motor on a 1980 arctic cat jag(the motors are exactly the same) and the new motor is running bad the spark plugs are white so im guessing that the jetting is way off. could it be the seals bottom end are crap, could it be that my oil to gas mixing is bad, or isit just the jets. im going to tinker with it but any idea's of what might be the problem would be helpful oh and it's back firing alot could that be a bad coil or just gas being pushed out the muffler and firing in the muffler. it also vibrates alot but it's pretty old so. i just need to make it run without it blowing up or melting down.