Water Flow to New Bathroom automated Flushometer

[mley]

I have a problem, i installed a new Kohler, 10956, 1.6 GPF auto flush valves on the second floor of a building,

i had to tap into an existing 1" Dom water pipe line on the ground floor, input to the building reads at 50 PSI, (i dont have a flow meter)

when i flush my toilets the 2" line pressure on the gorund floor drops 9 PSI,

ON the gage i have installed on next to the toilet my pressure goes from 54 PSI all the way to 13 PSI for a few seconds then slowly starts to climb,

The run is about 146' long 1" copper, and climbs bascially 36'

In my mind, i do not have enough water flow, enough though there is pressure shown on the gage,

What am i doing wrong?

[admin]

It is important if you have or not enough flow rate - and as you say, in your mind you don't, but it is not sufficient information - what flow rate do you need as GPF does not give me information about GPM flow rate to try to calculate.

Anyway the pressure should drop when you have flow rate, but if you still have flow on the end than it doesn't matter.