Just a couple of questions about this particular bike. I´ve got a similar bike,and am wondering if you have any idea of why there´d be vibration in the rear at moderate to higher speeds? Also,I´ve just come a pretty much complete motor for this bike and it being listed as a 2007 f act 50 evo. And mine is a 2011 f act 50 evo. Will these motors interchange even though they appear different in picture? I´m just wondering because the motor in question was stated that it was running and mine is running but, as I stated earlier I have a vibration in my rear end and thought maybe I could change out Motors if in fact this will interchange and fit on this bike of mine.