Awesome job. I'm guessing you need an accelerometer to since the speed changes and feed that to the servo to adjust the throttle. I'd probably add in a resister on a set screw for the sensitivity so its easily adjustable. Arduino is awesome and I'm sure you feel the reward of your efforts thus far.
I was heavily in to large RC helicopters and drones before the peeping toms of the world ruined it for everyone anf the FAA had to get involved. I was working with a friend on our own controllers. Its all the same principals.
1. 2004 DL1000
2. Next bike
3. Next bike
4. Next bike