I recently posted a forum about swapping from a 2001 motor to a 2006 motor. I am getting a backfire back through the throttle body. I changed the rotor/flywheel from the 23 tooth that came on the 06' motor to the 8 tooth that came on the 01' motor and now it just cranks over and over and doesn't fire. I pulled a plug out and jumped it across the frame and it fires every once in a while. Some people tell me it could be the cam sensor as well. I really need some help.