timing or carb
Your starter could be weak and need a rebuild.
get the lifters checked.
check or change the spark plugs & wires
If something else is wrong. My chain slipped and went through the crank case and destroyed the engine. But it was old. I've heard of this happening on other Yamaha's, so maybe their timing chains need to be replace sooner. not sure
Your Yamaha Bruin may not shift out of low gear because something may be wrong with the gear box, so you should have it checked.
It might fit but it won't work because the jetting will be wrong and with that big of a size difference the throtle will probably have too large of an opening in it.
0.6 to 0.7mm (0.024 to 0.028 inch) Previous answer was wrong! Sorry about that, that was for a "Warrior" 1987-2001 & up. For Banshee it's 0.7 to 0.8mm (0.028 to 0.031 inch) This is for 1987-2001 & up!!!!!!!!!!!!!!!!
my warrior spit out a gas and oil mixture out of the breather because the gas shut off wasnt working and the carb was letting the gas leak by so it actually pretty much overfilled the engine so bad it would fill the air box witht his mixture
No! its one of the worst WRONG
Sounds like your timing is off
Check the crankshaft sensor. Also check the timing and timing belt. The backfiring indicates that the engine is firing at the wrong time.
Check the timing.