Quote from another site.. 

 

 

"They are probably the easiest valves there are to adjust.
-Remove the seat, center plastic and side panels
-Remove the 3 bolts holding the gas tank down, there is a phillips screw in the fuel on off switch, take that out and the switch comes off, lift tank and unhook fuel line ( make sure fuel is turned off)
-Make sure you cover the fuel inlet on the carb, 350s are terrible for geting dirt in there and sticking the float valve open.
-Remove snorkle for airbox, Unhook the Wire harness clips and and plastic rivets from plastic heat shelid that sits under the tank. it should come right out.
-Remove the 4 bolts holding the valve cover down and take the valve cover off
-On tthe right side of the engine I believe there is a small inspection cover near the rear of the engine. You need a 6mm allen key to rmove this.
-Use the pullstart to turn the engine over until you see a T on the flywheel through the inspection hole. This is top dead center, both of the rocker arms should hae play in them, if not turn the engine over 360' until you see the T mark again.
-Use a feeler gauge to check you valve clearance , intake and exhaust are both 0.006"