There's a few things to check before you start tearing the engine apart:
Cam chain tensioner
Valve adjustment
Carb synchronization
Oil change (dirty oil, maybe?)
One thing at a time. Patience... :-)
Luke M
Used to have a 1979 CB750L, sold it as a parts bike, now riding a slightly modified 1984 VT700C. Network/Field Engineer. Central OH, USA, Earth, Sol System, Milky Way Galaxy, Universe.