my 2000 yamaha warrior starts and idles but when you accellerate it back fires thru the carb when going in a straight line, turn the bars it takes off and seems to run fine, go straight again and it spits and sputters again. I checked the simple things. fuel, fuel shut off, air cleaner, what should I cchech next. thanks for the help.

 

sounds like a pinched throttle cable...

 

check the intake manifold, it's common for them to crack down the middle and cause it to run erratically. Probably the boot is cracked, and just the movement of the throttle cable when the bars are turned is enough to push the carb side to side, opening and closing the crack.