Vibration

[ScooterDan]

Hey guys! I'm new here. The names Dan! Anyways, I live in Dominica and just purchased a Chinese scooter. More specifically a Jieda qt50 with a 1P39QMB engine. It has under 500KM on the speedo, but I purchased it with a broken speedo cable so i'm not sure of the true mileage. I do know it's not more than 1000 miles though. I've changed the engine oil and CVT oil. It runs well and I have no problems other than a vibration coming from the drivetrain around 30 mph (GPS verified) It feels as if it's about to implode! I know these little scooters aren't rated for much more than 30mph but to my understanding it shouldn't feel as if it were going to blow up. Any suggestions? Also, flat ground speed is average about 20mph which seems a little low although I am a bigger guy at 255. Again, it runs completely fine otherwise. Any suggestions? Also I am SURE it's not tire vibration.