Hmmm... James, you could be right- if so, here's my take on it-
while it may look a bit like one, a hydro bag is NOT built like an industrial or truck suspension air bag.
Think of it as a hollow rubber cone with fluid in, connected to another hollow rubber cone.- it is not a rubber pneumatic cylinder.
(Dr. puts on Engineer's hat- yes I is one..

)-
point 1. Normal pressure of 250psi approx (air or fluid) will only raise it to normal ride height. Getting it real high would take lots more pressure. And I doubt you will find a mobile source of air at 300psi..
Forget so-called 250psi air compressors from Supercrap or others..
point 2. Damper valves are built into the fluid lines inside the bags, these would seriously slow down motion by restricting airflow.
If you want RAPID up and down jig-a-jig motion, I'd do it with hydraulics as the Yanks do.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.
