hi. you have to go into tuning mode:

Tuning mode is used to change settings. Both
primary and secondary passwords are required
to enter Tuning mode.
Entering the Secondary Password
Enter the primary password.
Within 10 seconds, press the hour meter
select switch (system should respond with a
short beep).
Within 10 seconds, press the hour meter
select switch and the power control select
switch simultaneously (system should
respond with a short beep).
'Tuning" will appear on the display indicating
acceptance of the secondary password.

then you have to select the tuning code "C4" for maximum speed limiter: The factory default will show as the highest setting (1-8)
segments on. Moving down from the "8" will change the
maximum travel speed by 0.5 mph per character.

let me know if this helps.