No, engine diplacemment is not an the issue. If you could keep it hot, a sensor from a V8 could be used on a Briggs mower engine. A Bosch #11027 from AutoZone or Napa. They are around $18. They fit a wide range of cars like GM pickups, Dodge pickups, 87 Honda Accord, etc.
MV


46 Chev One Ton Panel - S10 Frame Project

"What if the Hokey-Pokey is REALLY what it's all about?" - J. Buffet