change the cam, I've done two in my 09, my buddy's 2013xc and a customers 2012xc they seem to be fairly common for some reason. and check the valve bucket underneath sometimes they wear funny
2015 freeride 154 aaen pipe, bondi box, diamond S hood
2013 600RS 128x2"
2009 ds450 vin#0001 13:1, dual ex cams, ron woods, pro armor, bcs, lonestar, walsh, blingstar, odi, itp, maxxis, AMR
2008 ds450X Yoshi, pink wire, AMR
2007 renegade 800 30" zilla's, snorkels, skids, high clearance arms and warn pro vantage winch
2006 renegadeX 1000sdi garbage motor got a 809 triple on the shelf and a 151" finger track
2003 7c special edition race ported 827 16:1 crankshop twins, 42mm bored TMx carbs