Only thing I can think of is $red_t1. Does this have any influence? Afaik 15 % is max. It implicity factors down the override so with a value of 7 in it for example 100 % override is stripped down to 7 %. Can be found in r1/$machine.dat.
Whats $speed_limit_teach_mode? It also affects maximal t1 velocities?
This thread also shows some facts on T1 velocities:
The PTP speed in T1 mode on the KSS 8.7 is unbearably slow.
How slow? Well let me tell you with the speed test example I run on two systems.
From Y -300 to Y 400 so a 700 mm running distance and measured the time in T1 mode while at 100% speed on the Teach Pendent.
KR C4 Compact
KR10 R1100 Agilus 2 robot (A six axis one)
KR C5 Micro
KR6 R700 Z200 (A four axis scara robot)
(Code, 54 lines)
System 1 (KSS 8.6.4)
PTP time: 9,684 sec
SPTP time: 3,852 sec