Don.
If you look at one of my previous drawings may be it explains the air intakes in an other way.
As you see from the image below there is in fact two inlets after the filter one to the top, first stage inlet chamber, light blue on my image, the air enters the inlet valves at the inwards stroke.
Then there is a second air trunk inlet flange for the combustion, scavenging and bouncing chamber, this air goes into a chamber light blue on my image. From this chamber there are a number of valves the first sets of valves A leads into the space under the first stage piston, at the outward stroke the piston draws the air in via these valves into the chamber behind the first stage piston. At the inward stroke of the piston the air filling the chamber is compressed shutting the valves A and opens the valves B and C into the scavenging, bouncing and combustion air chamber. The air is now filling this chamber until the piston is on the dead end of the inward stroke. Then the piston start its outward stroke creating a underpressure on the backside of the first stage piston shutting the valves B however the air valves C are on the top (compression) side of the piston and the air is still supplied toe the scavenging, bouncing and combustion chamber until the piston passes the valves C. and the valves C are connected to the underpressure of the piston shutting valve C.
I have tried more than 1 hour to put in the A,B and C on my old image but in vain due to my computer problems. Hopefully you are able to understand my idea without these letters. I expect to have the new computer ready by next week end.
Tore