I recently checked the valve clearances on my 08 YZ450. Two of the valves were out of spec, middle intake and left exhaust. I got the correct shims and replaced them. I also replaced the piston, rings and timing chain at the same time. I put it back together and checked the clearances again. The two that I replaced the shims on are in spec but now the right exhaust is tight, .18 mm, it was .203 mm before. I tightened the cam cap bolts to 76 inch/lbs in three steps in the sequence that yamaha describes. I did clean the carbon off of the head with a scotch pad but didn't remove the valves to clean them. Why is this valve tight? Thanks.