Last year I bought a 400 as first bike (scooter) I had ridden or owned. I now have 1000 miles on the 650 I bought a few months ago. I love riding and am also thinking of gettig a motorcycle. I had a severe rattle and thought I had a problem in second gear--- vibration causing it . Dealer had installed my new taller windshield and it was rattling. Motor seems to vibrate when I throttle hard at about 23 to 33 mph. Is this normal? I am in Wisconsin.