Check your carbs to see if they are in sync.. check the cables to see if they are not hung up somewhere... make sure on th caps, the cable is all the way down.. If they are not put together right, one will pull before the other until the slack is out..
check the reeds.. might have a broken one.. check the spark plugs by removing them but keeping them hooked up. have your friend give it a couple of kicks while you watch.. ( for kicks, have your friend hold one while you kick) (Important.. not your wife!!) Id go for the cables first..
let us know..