At the very least, that lawn mower engine won't be able to operate at any sane RPM! And I agree, it will be a gas guzzler. Our current engine technology is much more efficient at lower RPMs, and that requires either flywheels or multiple cylinders, or both.
Take a look at this 102 RPM two cycle engine!!
Concerning SM's technology, there is no circuit loop for the high voltage resonant circuit. Thus, no high current to go with that high voltage.
Coffey