If you need to get more throw out of your servo linkage, there's a few things you can do.

Check to see if your radio has end point adjustments. If it does, see if the EPA for throttle is adjusted high enough.

You can also try using a longer servo horn (move throttle linkage to a hole further away from the center of your servo).

Check to see if your servo is centered properly on your radio. Set your radio adjustment in the neutral setting (center the adjustment dial, digital bar, etc). and adjust the servo horn on the servo spline.

If you still need a little more forward travel on the servo, turn the adjustment dial counter clockwise (toward more brake) and then readjust the servo horn for the new "neutral" position accordingly. Doing this will reduce the travel for brake but increase the travel for throttle.

Good luck