It would be very difficult in any gear, on flat ground, to exceed 6K RPM without using a high enough amount of throttle angle to engage VTEC.

Factory VTEC constraints:
-20% (IIRC) throttle angle
-ECT relaying operating temp to ECU
-Oil pressure signal to ECU high enough to engage VTEC
-VTEC hardware/software in good working order
-VSS reading to ECU above 12mph.
-ECU reading RPM threshold

OP's VTEC almost surely works. Its just inherently difficult to notice in 1st gear.

 

The VTEC now constantly engages on my S2000. I was talking to a Honda Tech and he thought it sounded like octane/injector problem and recommended adding a can of Seafoam to my next tank of fuel. I added the Seafoam and after a few hundred kms it is back to working fine. Thanks for your ideas

 

chck vtec screen( filter)

 

if it is clogged it wont engage vtec