There a very quality and in depth comparison on smj about the 250x and drz400sm. Even with the smaller displacement the additional gear allows the smaller 250 to keep up with the 400s. Their great bikes and the maintenance intervals are awesome. Glws nice bike.
Plenty of vintage scoots for the price of that electric. Historical tags, 70mpg and 65mph done. I'd pass on a 30mph top speed That scooter would be good for someone in NY, LA, or a big city where your going 25mphto or less
Definitely a ground or your picking up ground loop noise from the rca's. I would check all battery grounds, amps, grounds then go from there. I can help you this weekend bubby