In any motor or generator it always helps to minimize the air gap that the magnetic field must traverse, but I think the moped manufacturers have pretty much optimized this: you do not want your magnet to hit your coil's armature under any circumstances, so I'd leave it alone.
(The air gaps in the generators at electric power plants are extremely narrow, so narrow that a good deal of excess heat is created because air gets compressed when the molecules are dragged by surface adhesion into the space between the rotor and the stator. And so instead of air, the generator case is filled with hydrogen gas, which is far more slippery than air. The rotor spins at 3600 rpm, driven by a shaft that's maybe two feet in diameter. About half a million horsepower is involved in the larger generators.)
What you probably do want to do is trace wires to see if any previous patriot has tried to improve the wiring arrangement. On my bike you can arrange those connectors any which way, and the screw slot in the headlight has a suspicious amount of wear.
I'm going on another diode-hunting expedition as soon as I get done replacing the ancient crankshaft seal that's letting fuel vapor coat my clutch plates. (It's really great: bike stalls, and then the clutch slips so you can't restart it.)