[hawkman]

I know this one!!

I had a Century Hawk and this had the same problem.....its actually down to engine tuning.....the engine might be 'pre detonating' which will definatley cause a bad vibe.

The solution is to re tune....use the low end needle....this is the tiny screw inside the throttle arm/barrel.....you can then use the main needle too...the idle needle affects running from idle up to the hover point....the main needle has a strong influence of course....but get the idle needle in the sweet spot and the sloshing will stop.

Do not try using a header tank or any device....it wont work....the air bubbles still get in and will get into the carb....which causes more problems...notably the tail will swing about....where you then blame the gyro!

Take your time with the tuning....always make sure there is some oil on the skid below the exhaust...this means the engine is getting lubrication.

The problem isnt helped by the fuel tank....its held ridgid between the main frames right? I tried isolating mine by mounting it lengthways and had to make a base to do this....but it didnt help at all.

Its tuning for sure.

Rob