Yes This Bike is a "Simplex Servicycle" .Still quite popular item,,with the serious Antique Motor Bikers they made 2 wheelers and a 3 wheeled sevice car,trikes...Although this one does not have it's original 2stroke single cyclinder motor It appears to have a Briggs and Straton 2 or 3 hp motor driving it's orginal belt drive..
One very interesting detail you can order from "Coker tires" a speed rated tire ment for the Simplex,that can be used on say a wide worksman 26" bicycle wheel..
During the Portland ralley this year I saw numbers of these Simplex Servicycles..ranging from 1500.00 to 6000.00 bucks.. they are quite Cool and if ya find one with it's orginal motor now you have a real peice of Americana..

Helmutt