Scarecrow and Mrs. King

Harley ? Aucune chance... Kawasaki, plus vraisemblablement...

Circular cam caps, this is a Suzuki.

Headquarters of the Metropolitan Police Department of the District of Columbia, 300 Indiana Avenue NW, Washington, DC These days, MPD uses Harley-Davidsons. Not sure about the 1980s.

think it is more like an Enduro Honda XL 500 or something like that

old Honda ? Yes, Elite. Nothing for the Datsun 1200? no better shot

Made separate entry for it here anyway: /vehicle_891199-Datsun-1200.html

Looks like a Vespa... in the 80s you were safe from chinese crap copies

Yes, Piaggio Vespa P. Still, these weren't devoid of pecularities, either.

look's like a Honda XR's

Yamaha XT 500 du premier millésime?

Looks too small to be a 500.

so which do we take ? The one on the left.

Harley -Davidson ??

I think the bike on the left is a circa 1982-84 VF 750 C Magna 45 and I think the other two are Honda CB 650 SC Nighthawks from the same era.

Sur la base de la 650 CBX, soit la deuxième version...

Not a Harley, it is a circa 1983 Honda VT750C Shadow. http://www.motorcyclespecs.co.za/model/Honda/honda_vt750c_shadow%2083.htm