There's been a lot of talk lately in various specific kit-related threads about engine choices for the experimental light bush plane class. The powerplants available range from 80hp to 130hp, and target the weight range of generally 2-seat aircaft with max gross weight less than 1600 lbs.
What do we have? Here are a few purpose-built aircraft engines. I've chosen to ignore the auto conversions.
Rotax 912 ULS (80 or 100hp, experimental only, Austria)
Notable: liquid cooled heads, electronic ignition, dual carburetors, and gearbox.
Continental O-200 (100hp, experimental,certified USA/China?)
Notable: Tried and true design, lighter than original O-200
Jabiru 3300 (120hp, experimental only, Australia)
ULPower 350i (118hp, experimental only, Belgium)
Notable: Fuel injected, FADEC, electronic ignition (no mags or breaker points)
Rotec R2800 (110hp, experimental only, Australia)