There would be only one set of wires i could even think of that would go into the motor and that would be stator wiring. Is it a single wire or with 4 or 5 others? And if it is stator wires if its messed up close to where it goes into the engine you will need to remove the stator cover to repair it mostlikely. If its a single green wire then it mostlikely is the neutral safety switch wire. That wouldnt go inside the engine at any point though. It would just have a rubber plug end connector to go on the neutral safety switch. Not sure on the 250ex where that switch is located though so i cant really help you there. But if its out in the open and not to close to the motor i would do what retro said. Solder a new chunk of wire in and heat shrink it. Or you could use butt splices with the water proof heat shrink on the ends. If your not comfortable soldering. My .02