Can you tell me the brand of soft start that you are using. a Curtiss perhaps ?? Do you control the soft start with some form of electrical control potentiometer ??
Bosch makes a world of pumps ??
Sure nice to have someone with an extensive back ground in hydrualics here on the forum. This way from time to time I can ask some dumb questions and know I will get a an informed answer
Vance….the .7 cu.in. pump/motor is only rated for 1500 psi continuous and the relief is set to 2000 psi.
You would reach 200 rotor rpm at just under 2000 engine rpm so there is no reason to run the engine higher until the pre-rotator is shutdown.
You could use another relief valve set for a pressure low enough to get a soft start, but you would still need to add a shut off valve (manual or solenoid) to close that relief line so you could finish the pre-rotation.