I have this cool-looking gas engine. Roto 25V, made in the Czech Republic by Rotomotor.
Does anyone have experience with this engine?

Yes I have one with about 4gal of fuel thru it very good running engine swings a larger prop than other 25cc I have a 3 blade 17x6 on a scale plane has tons of power only complaint is its weight weighs a lbs more than dle 20 that swings a 16x6 the recommended prop for the roto 25 is 18x6 the engine has a longer stroke producing more torque

Also I started to break it in with a 16x8 but ran hotter at high rpm’s so I went a 17x8 to finish breakin and engine ran much cooler