Motor heat - which way do I go with the gearing?

[VintageMA]

Setup: XB8EC geared 14/48 w/ 1512 2.5d (2050kv) on Neu 3900 5S. (Geared for about 40-43mph).

Great setup, but temps at the end of 15 very hard minutes:
-Battery - 100*
-ESC (mm w/fan) - 130*
-motor - 158*

Average current ~14amps, according to Watts-Up meter max current 72A.

I went from 17/48 @ 4S to 14/48 when i moved up a cell to 5S.

Most threads here show cool batteries, cool/warm esc, hot motor = undergared.

I am not sure if that is the case or not, so looking for some input on the gearing direction people feel I should go. Am I trying to hard with the motor or not putting enough load on it?

Which way do i go the get motor temps down? 13/48 or 15/48.

Thx.