ORIGINAL: gaRCfield
I love thermodynamics and once I saw/read how the YS uses the chamber under the piston to compress air and feed it into the combustion chamber, along with pressurized fuel, I had to have one. Sorry I can't find a link right now.
It's in the owners manual:
The FZ110S .....
This engine offers many exclusive features that have been proven on
other YS engines.
Supercharged system with simplified structure to keep weight to a
minimum while still retaining maximum efficiency.
<span style="color: rgb(255, 0, 0);">Air chamber that uses crankcase pressure coupled with a double
throttle valve system which allows a bigger charge of fuel and air
mixture to enter the intake valve for more power</span>.