Ultralight engines?

[cavelamb]

How about a Hirth? Not necessarily inexpensive, but good engines with long TBOs. Here's one source: http://www.recpower.com/3203%202%20cycle%2065hp.htm I seriously considered buying a Challenger with one of these instead of a Rotax.

Way too heavy...

Weight:

79 lbs-fan cooled including electric start and exhaust.
Optional gearbox adds 19 lbs.
98 pounds?

[Scottluther111]

Has anyone tried the 4 stroke helvenco/ swissauto250 (aero version), Blackhawk paramotors imports them as interuder 250, on a part 103 ultralight? I’m rebuilding a kolb firestar, early single seat, and was looking at engines... light ones that might work. Polini Thor 250 ds, simonini victor. Any ideas? The helvenco is 4 stroke, 36hp, water cooled, EFI, and weights 69lb with oil and water.