[Tinker]

I would suggest reading many of the threads in this brake category, starting with "I give up on bleeding my brakes". Your question seems to be a popular one. If that doesn't work, you need to be more specific on your system, including master cylinder bore size and caliper piston areas. The proportion valve should be there to limit rear brake force only. Removing it will not help overall force, unless it is incorrectly installed. I hope this gets you started.