Exactly where you need to find these things
<vehicle name="vehicleMinibike">
<property name="cameraDistance" value="3, 4.5"/>
<property name="cameraTurnRate" value=".2, .35"/>
<property name="upAngleMax" value="70"/>
<property name="upForce" value="1"/>
<property name="steerRate" value="130"/>
<property name="steerCenteringRate" value="90"/>
<property name="tiltAngleMax" value="20"/>
<property name="tiltThreshold" value="3"/>
<property name="tiltDampening" value=".22"/>
<property name="tiltDampenThreshold" value="8"/>
<property name="tiltUpForce" value="5"/>
<property name="motorTorque" value="400, 200"/>
<property name="turboScale" value="1.4, 1"/>
<property name="velocityMax" value="7, 4"/>
<property name="brakeTorque" value="3000"/>
<property name="hopForce" value="1.5, .2"/>
<property name="unstickForce" value="1"/>
<property name="waterDrag_y_velScale_velMaxScale" value="1.5, .9, .15"/>
<property name="wheelPtlScale" value=".6"/>
First value in motorTorque is forward direction, second one is backward direction
Motorcycle and 4X4 motor torques for comparison
<property name="motorTorque" value="1400, 500"/>
<property name="motorTorque" value="1800, 900"/>
Code to put in a modlet so you can change them
<set xpath="//vehicle[@name='vehicleMinibike']/property[@name='motorTorque']/@value">X,Y</set>
Change X,Y to the values you want.