I'm not too clear on whether the 1917 engine is actually 2 stroke Ty, I may have just failed to find the valve gear.
This report on the 1894 Mietz and Weiss 6 hp engine - a direct-injection 2 stroke - says it was initially hit-and-miss governed, then later throttle governed, but judging by the photograph it was a bit bulky for lawnmower use:
http://www.coolspringpowermuseum.org/Publications/Flywheel/Flywheel_201106.htm
