Could be that the dyno is just stingy.  My raptor 660-makes 50.2 hp on one dyno and 58.4 on another.  Thats a big variance, but be more concerned with how it runs than the number it puts out.    We all want our quads to put out the big numbers we see from Dales bike on Jerrys dyno.   Perhaps jerrys dyno is just one of those that tests high.  Run dales bike on a stingy dyno and it doent look as good.  But it is just as good.  Nothing changed but the number.  And dales bike probably has every last once of power extracted from it too.