Lip on the Tail - what bike was first?

[Scud]

The 1980s Moto Guzzi LeMans 4 and 5 both have an upswept lip on the tail, like a little air foil.

This also was on a 1985 FJ1100 I had (and I was just looking at an FJ1200 wondering if I would enjoy "re-owning" that model.)

And a similar style tail section was on the early 80s Honda CB1100F (also the CB750F and CB900F, which were earlier)

So... what gives? Where did this tail style originate? Was there some theory that it helped airflow? What was the first motorcycle that had a tail that said "Give me a little lip, baby?"

[footgoose]

1973 Kawasaki Z1 900 had one 'of sorts'

[po18guy]

19 minutes ago, footgoose said:

1973 Kawasaki Z1 900 had one 'of sorts'

More like a ducktail, was it not? The 1972 H-2 750 may have been the first, styled after road race bikes of the day.