Did you adjust the valve clearances when the engine was dead cold..like after it sat overnight? Cuz if you adjust them when the engine is warm they wont be right. Actually, it COULD be your cam chain, especially if it hasnt been adjusted in 11k miles. See that contraption coming out of your cylinder block just below the carbs/intake manifold? Thats your cam chian tensioner. Do a search on how to adjust that in the FAQ section and be advised that they commonly get stuck. Not trying to imply you dont know your bike but I have no idea of your experiece. And hey welcome to the forum. Lots of good guys and info here! Lots of good B.S. too! Later.