The speed is unstable. When the speed of 80 yards increases to 100 yards, the car rushes.

The problem is similar to the landlord's, high-speed throttle, 1500-2000 speed up and down several times, occasionally. By the way, I went for maintenance today, saying it was a problem of upgrading. I thought the throttle was too dirty, so I washed it. The throttle was not too dirty. I ran around to see if there were any problems.