you seme to have a very bulky front end and a failrly plain back end. that would throw your ride way off balance especially in any turns, making you fishtail like mad. i guggest moving the gass tank downn a little. sloping it more with the frame and geting rid of the jesse james stle new rider.

Possibly extend the exhaust a little and add more detailes to the wheels. and the rear tire needs to be a little wider

I plan on modeling a bike soon.