New 2009 yamaha xt 250 idle changes at random. The dealer tried a different sized pilot jet and adjusted the mixture, but the problem is still there. And now I get 50 m.p.g. when 73 m.p.g. is advertised. The idle still randomly goes up and down when in neutral or while riding at steady throttle. They canĀ“t figure it out.. Does any one know the fix for this problem?