When RC Helicopters start vibrating, either the main blades or the flybar are unbalanced. The flybar can be balanced in one of three ways:
1. Adjustment of the flybar weights. However, on cheaper Electric Helicopters this is often ineffectual.
2. Moving the flybar paddles.
3. Moving the entire flybar on the rotor mast.
The third method is the best, as it is quick to do - you are dealing with both sides of the flybar simultaneously. The downside is that it can lead to wear on the flybar if the screws are repeatedly retightened. It’s best avoided on cheaper RC Electric Helicopters.
First, make sure it is the flybar that’s the problem: secure the heli and remove the main blades. Disengage the rotor and start the engine. If the flybar is unbalanced, the helicopter will start to vibrate.
To adjust it, first, mark the flybar on one side, where it meets the retaining nut on the rotor head (a fine glass marker is best). Measure the distance from this nut to the flybar weight.
Now loosen both the retaining nuts so you can slide the flybar from one side to the other. Gently slide the entire bar in or out - no more than 1mm to start with. It may need a wiggle to get it moving.
Check again for vibration; if it still occurs just keep adjusting until you get the best possible ‘fit.’
This method is particularly good if the vibration is severe (although this is rare in electric helicopters, unless there is severe warping elsewhere)
The sequence is: Dampen down the movement as much as possible using the method above; make finer adjustments by moving the paddles; trim out any very minor tremors using the flybar weights.