700 Vibrating problem

[Arwel]

I flew my 700 for the first time yesterday and noticed that the fuel was frothing at high rpm. Even when the heli was on the ground, you could feel the vibration through the side frames. Could it be the fan thats out of balance?

[moonmanflyer]

Could me many things mate.
Are you using a pumped motor? that can cause a bit of foaming.
Have you fitted both magnets in the top clutch hub?
What ever the 90's do suffer from vibs more than the smaller heli's, regulary will be doing fastener checks on mine

[Arwel]

I'm using the OS 91 Pumped motor and I'm not using two magnets. Will need to try that bud!

[moonmanflyer]

I'm using the OS 91 Pumped motor and I'm not using two magnets. Will need to try that bud!

Yeh put the 2 magnets in, if you have fitted just the one it will be unbalanced.

[robgt]

If you have a kit from the first batch, the frame holes where the tank sits are a bit small. Dremelling about 1mm from the back edge and bottom edge (making a 0.5mm larger gap all around the tank hole) will allow the tank to fit more freely and not cause the fuel to foam as much, or at all.

Something slightly curious that I noticed last night is that it appears the new fuel tank (replacement tank) is fractionally smaller than the original one that came with my kit. Where my original fuel tank was a snug fit after I had dremelled the sideframes, the new one is most definitely a lot looser in the same space. It won't fall out, but it almost certainly would have been a straight fit into the standard sideframes (without dremelling).

Basically, make sure your tank isn't too tightly fitted to avoid fuel foaming
Cheers,
Rob

[moonmanflyer]

Yeh mine was a very snug fit to say the least.

[Arwel]

Would it be worth buying a new 'smaller' tank rather than sanding the frames?? I have put two magnets in it and will be testing the fan etc on a dti tomorrow.

[steelie600]

jeznewsome has also got this problem on his 700. dont know if he cured it yet tho

[raptorheli2]

my 700 has vibe problem. i put a thread up showing how badly made/dialed the fan and clutch assy ends up. i bought a clutch which helped but i'm waiting on align releasing a hub so i can fix the problem....not happy.

cheers

[robgt]

Would it be worth buying a new 'smaller' tank rather than sanding the frames?

I think so... it would certainly be an interesting test to see if what I think I'm seeing really is the case!
My new tank is definitely a looser fit in the same space as the previous tank.
Cheers,
Rob

[simm0]

bloody hell lads..this heli aint looking good.vibrations and poor fitting tanks etc
sorry to hear this
cheers craig

[andylinney]

just thinking out loud here but might it not be possible to pop the fan / clutch onto a lathe to skim off the imbalance and having running true. Now I don't know if this'll work or just make it worse but it's a thought none the less....