Artic cat dvx400 valve shim question

As stated working on a 04 dvx400. Total top end rebuild with new valves and I got the dual overhead cams timed right but when I check the valve clearance it's off. Have never really dealt with shims before, just tappet arms. I measured and adjusted the exhaust to the biggest size that comes in the hotcams kit of 3.50mm and I'm still too loose on the clearance. The intake was still in spec even with the new valves. Is it possible that the shim buckets have just worn too much or am I overlooking something.