Way Back When, I started out in this hobby with a of Rossi 0.81 motor and Dynamax tractor fan, Installed in a Yellow A/C F-16C..
I could never get the Rossi reliable enough to actually fly, and eventually replaced it with an O.S. 91, and never looked back.
A friend of mine owned a Rossi 105 DF which was also very unreliable. He however, is a very talented mechanic, and persisted with it, although with a lot of modifications. Eventually it was a very powerful motor, driving the Ramtech fan unit although it was never as easy to operate as an O.S.
One of the many modifications required was to fit an OS carburettor, which was very expensive to purchase as a spare part.