[ozrien]

The LV loop works better likely because you set the min output to '0', which means you are likely overshooting the RPM.

You can do the same thing with Talon SRX by using the "TALON - CONFIG PEAK OUTPUT".vi and setting in the "Reverse Peak Output" to '0'.

Try freshly calculating the F-gain (zero P, I, and D) and start with that (no load).

Then test at various RPMs to see what your error is like. Then start increasing P until the closed-loop begins to oscillate (then back off).