A friend pointed me to this site which has all sorts of 'how to' instructions.

http://www.instructables.com

One of the features is 'How to build a 72volt electric motorcycle' using an '84 VF750 as the donor. It's a nice job too.
http://www.instructables.com/id/How-...ic-motorcycle/

Found more, there's a few bikes on there.
How to build a 96-Volt Electric Motorcycle - Using a Yamamha Seca Turbo
http://www.instructables.com/id/How-...ic-Motorcycle/

48V Electric Flat Tracker
http://www.instructables.com/id/48V_..._Flat_Tracker/

Easy DIY Electric Motorcycle Conversion - Using a Honda Rebel 250, this ones not so pretty
http://www.instructables.com/id/Easy...le_Conversion/