Here's a great Plastic Repair kit for ABS Plastics. Most sportbike bodywork is ABS Plastic. Most dirtbike is Polyethylene but this stuff can be made to work on it. It just takes a different type of repair. The ABS stuff is easy; watch this: http://www.youtube.com/watch?v=6xBIf...ww.plastex.ca/

Let me know if you want some; I carry the Plastex kits

 

easiest way i have ever found is to get a putty knife (smaller one) and a butane torch, heat the knife red hot and lightly touch the broken edges. hold in place until plastic "slides" and then put both broken pieces together and slide the knife out while holding the plastic together.
go over with sand paper and good as new "ish".

sorry if that is the same way as shown but i cant get youtube at work