this is really interesting ... as Poirot says this is where the plot, em, thickens.
My bike has the "BMW 4 Valve" metal spark plug cover plate ...
The thickness isn't in the plot. You've been led astray by my error—which has now been corrected and by its longevity indicated few are reading this, or care enough to point out errors
—and now you're coming back to the fold. You should download the K1100 Workshop manual from here to inform
yourself.
The engines of classic K motos are described in two differing ways.
2V indicates two valves per cylinder for a total of 8 valves per engine, making it an 8V engine.
4V indicates four valves per cylinder for a total of 16 valves per engine, making it a 16V engine hence your spark plug cover
4V identification.
BMW tends to use 2V and 4V in their publication titles.
Here are some identifiers—for fun.
Extended throttle body manifolds. Sometimes they are insulation covered.
The earliest have an ignition amplifier in front of the battery cover
All 4V (16V) have a Motronic control unit instead of a Jetronic fuel injection control unit.
It's time to return to the foot peg plate/exhaust hanger conundrum.