http://www.segway.com/segway/component_details.html

States the motors are brushless servo technology. Sounds like a brushless
DC motor. Bottom line; the motor is running on DC, not AC.

They also appear to be use high tech magnets etc to pack 2.5HP into
a small package.

A far cry from using an old Heavy industrial 7.5HP AC motor that will
have a very limited speed range too.

I think anyone attempting to build an electric motorcycle by scrounging
up parts won't get very far.

I own 4 electric scooters. The better ones use three 12volt batterys
feeding a 36V DC motor. Surprisingly quick for a 350watt motor.
The whole scooter weighs 65 lbs and will carry an adult very well.
Very simple and works.