With the piston @ TDC the cam should be as follows, the 2 small holes and or lines will be parralelle with the top of the head, the large single hole will be pointed at the seat back. Every completed direction of travel of the piston is known as a stroke, so when the piston travels twice down and twice up it has completed 4 strokes. Within these 4 strokes the cam rotation will be once for every 2 rotations of the crankshaft. So the first time the piston reaches the top this is known as TDC the next time the piston reaches the top is known as BDC or bottom dead center. At TDC both valves will be closed whereas at BDC the intake is just about closed and the exhaust is about to open. Hope this helps you to understand and not confuse you. The valves should be set on a cold engine with the intake set to .003" and the exhaust @ .005". The setting you have at .002" is too close and will not let the valve rest on the seat long enough to dissipate the heat generated on combustion, and will eventually burn the valve. After trying to start the engine several rotations pull the plug and tell us if the plug is wet from fuel or dry.
TOM
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