Checked the valve clearances on my 2011 YZ450, still exactly in the middle after 75 hours. Checked my 2015 YZ450 for the first time at 20 hours, but discovered that the Intake clearance tolerances are different: .004 - .006 (2011) versus .005 - .008 (2015). Exhaust clearances were the same. Just curious what changes in the engine design led to the larger clearance? Also noticed the breather tube is larger diameter on the 2015.