It's been a while since I installed my Givi bars, but I believe that I supported the motor with a stack of lumber. The motor won't fall out when you remove that upper motor mount, but it will drop down a bit, so it needs to be supported. The little 296cc motor in these things is really not very heavy. The most aggravating part of the install for me, was torquing that upper motor mount bolt without spinning the two brackets. You'll know what I'm talking about when you get to that step.