Good on you, Alex.
I have an MZ202 fitted to my Eros, and have been very pleased with this excellent engine. It is light, powerful, compact, & starts easily.
In my view it is the best choice as an alternative to the Rotax 503. It is lighter than the 503, and less bulky than the 528 - also has simple fan cooling so you don't have the hassle and form drag of a water cooling with a radiator.
Good luck with your engine sales.
Bruce |