I ran my sled for a while untll i noticed the midle cylender dosent fire. I thought maybe it could be the a bad plug wire so i switched all the plug wire around and still no fire but every other cylender fired. Then i thought maybe fuel problem i re did the carbs fully had then all set back to factory specs with a mercry stacks, and still no fire..Then i thought maybe its suckingh air some where so i took off the middle jug and got a new gasket and put permatex on it and slaped it on and put it back togather and still no fire. I had a guy come look at it he thought maybe a crank seal cuz when the air boxes are off and you cup the carb intake it has noo sucktion at all. But what he says thats not right is that if it was a crank seal i still should have sucktion on that middle cylender.. I have no idea what it could be anymore i need some help!