Had a very interesting conversation with a realy nice chap on an e-bike forum in the UK. He suggested that I look at Enertrac hub motors too in terms of gaining some choice for hub motors. Website is: http://www.enertrac.net/product.php

Product text for the Enertrac motor is:

This motor was designed to make the gas to electric motorcycle conversion easy, with such features as a 60mm O.D. hollow axle designed to accept the standard bolt axle used in almost all motorcycles. What is required with a motorcycle conversion using a hub motor is the design of a torque arm that prevents the axle from rotating. This Torque Arm was designed for direct integration into most motorcycles swing arms. Other features of this design that stand out when compared with other hub motors are large mounting area and easy mounting of a Disc Rotor, and high efficiency design.

No other hub motor on the market today is design exclusively for the motorcycle conversion market. The motor uses a higher voltage, lower current design to minimize losses from wire heating. It is able to achieve 10KW continuous and up to 30KW peak. The motor is thermally protected when using the recommended Kelly Controller to prevent overheating and burn out. The Hub motor is designed for motorcycles weighing less than 400 pounds with the batteries (dry weight, no rider).

The Hub motor will come laced to DOT compliant rim, WM3 style 36 hole, 18 X 2.15, other sizes available on special order, or order just the motor and have a rim of your choice spoked onto the motor.