Just got a new 4 mil banshee and I was hauling ass in 5th gear and the plug got fouled. I replaced the plugs and it won't start. It started first kick every other time. I put both chokes on and held the gas down and it will start run for a couple of seconds and die. It backfires sometimes too. It doesn't sound right when you kick it or it runs. Thanks for any help. Fresh rebuilt carbs and motor