Just thought it might be interesting for all 250 flyers.
I had a major erratic tail wag problem on my new HK 250GT. I have a very docile hovering set-up. There was nothing predictable about the wag. It would come on any time without warning. I did a huge amount of research and found that wag on the 250 was a regular affair. That discouraged me a bit. People came up with a whole list of possible reasons including binding in the tail; too much torque - so shorten the blades; changing my gyro-tail servo combination; using chinese weights and so on. The simplest suggestion was to lessen the tension on the belt drive. I decided to take it a step at a time and went with the belt drive suggestion first. And guess what? It worked like a charm. No vibration...no wag...and a good smooth machine. Here is my set-up:
1. Radio - Futaba
2. Servos - Three HXT 900 and one TGY 90S (for the tail)
3. Gyro - HK 401B (wish I had a smaller gyro. This one is a bit of a tight fit on a 250)
4. Gyro gain 15%
5. Throttle - 0 - 35 - 65 - 80 - 100
6. Pitch - 40 - 45 - 60 - 75 - 90
Everything else on the heli is standard "out-of-the-box".
Hope this helps someone out there.