Non sparate sui bambini

Nice Bertone Helmet I think this is one of the H-D Cagiva 2 stroke SS-SST range (what were they marketed as in Italy? They were originally built by Aermacchi), somewhere between 125 & 350.

Agree. The naming changed several times for this model: 1975-1978: AMF Harley Davidson, 1978-1980 HD Cagiva, 1980+: Cagiva. By the film release date we have here probably a Harley Davidson (SS/SST).

Yamaha ? Looks like it, I think XT or more likely TT500. Maybe an MX?

The 1st thumb is a different bike with aftermarket alloy tank. It's a monoshock so if 250-400 it's 1975 B model, very little info available on 125-175 (as opposed to DT---MX) but the monoshock versions appear to have the same tank & side panels as the DT models. Still doesn't resolve the main pic, you could be right on MX but I'd like to see motor & rear suspension.