The best way to tell if the valves are closed is to observe the rocker arms. When they are both at the top of their travel, valves are closed. Feel the rocker arms and try to move them, if they move their at the top of their travel.
-intake: exhaust closed, intake open -compression: exhaust closed, intake closed -combustion: exhaust closed, intake closed -exhaust: exhaust open, intake closed
17mm or 0.016" both intake and exhaust. Valves closed.
Yes the intake and exhaust valves have to be close.
Trace the runners. You can see the exhaust runners leading to the exhaust valves, and the intake runners leading to the intake valves.
0.016" cold both intake and exhaust. valves closed
Both the intake and the exhaust valve are closed.
Exhaust valves are always smaller.
At TDC of the compression stroke for cyl #1, the cam lobes will be in a position such that they are putting no pressure on the valves, and valves are closed. At TDC of the exhaust stroke for cyl #1, the lobes will be in a position such that intake and exhaust valves may be open. Exhaust will be closing, and intake will be opening. There are two revolutions for the crank for one of the cam. TDC usually refers to TDC of the compression stroke, when valves are closed. This is when combustion/spark occurs, and is when the valves are adjusted on most engines.
Closed.
Closed
Closed
The intake valves are bigger, and lead to the carburetor. the exhaust valves are smaller and lead to the manifolds or headers.