Not technically. On 2s you'd be within the motors stated limits, but I found the 6900 and 7700 CM36 motors to run very hot even in a lightweight setup. In my 1/10th 4wd buggy, I was able to move from 7700 to 5700, gear it up a a bit to compensate for the lost top end, and I ended up with a setup just as fast, but with much more manageable temps. As a bonus, the runtimes were much better as well :).

Basically i would only use the 6900 or 7700 series in lightweight onroad cars. When you start putting more load on them, they just heat up too much.