Are there any restrictions on what can be done to the habdout motor? At the on road masters, drivers were not allowed to run their motors in in water. I think a better idea is to hand out motors just before the race and hand them, back after, with a shuffle of the motors before the next round.
That way, there is no incentive to tamper with the motor as someone else will have it in round 2 and 3.
Just a thought, fire away.