i am working on a friends 03 raptor 660 it wouldnt start found out the pick up coil was bad replaced pick up coil stator it ran for 15 min then died no spark checked everything over again couldnt find anything so i replaced ignition coil keyway on the crank and rotor (flywheel) it will run strong for 15 min after i put it together then it will start breaking up and die then it will only spark here and there. i am stumped any advice please i have checked and ruled out the following
ignition coil and wires
plug
pick up coil
stator
rotor
keyway
starter clutch *i know its a common problem
cleaned all grounds
swapped cdi w/ friends
cleaned and checked whole wire harness and switches
valves and timing

 

did you check your spark plug cap? also check and make sure the connections from the stator are tight. i had the same problem with mine and i moved the wires around and now i have plenty of spark. also the plug cap can cause you to have no/off and on spark. i had to replace mine because it was worn out and very loose.

i would check those two things. spark plug cap and stator connections.

before i forget, you may have did this already but check and make sure none of the wires rubbed against the frame and grouned out.