Hello, Just purchased this item. It has about 10 minutes of use so far. Love it in every way so far. My only concern is that the engine runs super smooth from 0-50% throttle. From 50-90% there is a small vibration, from 90-100% there is a bit more. Is this normal? Why would the engine run smoother at lower RPM's. You can even see the head unit shaking a bit at higher RPM's (close to 100% throttle) I am not convinced there is anything wrong with it, I think it mat be the fact its a single cylinder engine. Any feedback would be appreciated. Thanks, Aristole Zoulas, Warwick, NY