head vibration on spool up

[VAN HELLI]

ok guys try figure this one
blades on blade grips not to tight...
spools up then just about to lift off there is a head vibration then it disapears then lift off..

ok to make sure its not just aligning the blades for the first spool up after set down let headspedd stop try again and the vibration is in the same stick position and head speed

blades are balanced and weigh the same (excactly)

????????????????????????
any ideas

thanx

[Raydee]

What motor are you running? I have the same thing and after carefully balancing the mains and tails I think i narowed it down to the outrunner motor. When it hits a certain RPM it sends some major vibes through the heli. I have heard of guys balancing the motors but the vibe isn't bad enough to make it a big deal.

[VAN HELLI]

changed the training gear for smaller lighter shorter sticks and most of the viberations are gone!!!

crazy suppoze its because the helis is so light

ok thanx

cheers