These are the dimensions of the motors that drop into the razor mx500/650
And these are the dimensions of the 1000w motors
As you can see the 1000w motors (36v and 48v, I checked) are all almost 3/4 of an inch longer and to make sure the sprockets line up you'd have to shave off that 3/4 of an inch from the left side (opposite of the chain side) of the swing arm, reinforcing what remains to avoid flex and warping and remake the 2 hole mounting bracket to accommodate the 1/2 inch wider diameter... a substantial amount of work for gaining 200w over the drop in 36v 800w brushed motor, 48v 1800w or even more powerful brushless motor. Can it be done? Absolutely! But I'm pretty sure even Helen Keller could see that it's not worth the hassle in the end.
And these are the dimensions of the 1000w motors
As you can see the 1000w motors (36v and 48v, I checked) are all almost 3/4 of an inch longer and to make sure the sprockets line up you'd have to shave off that 3/4 of an inch from the left side (opposite of the chain side) of the swing arm, reinforcing what remains to avoid flex and warping and remake the 2 hole mounting bracket to accommodate the 1/2 inch wider diameter... a substantial amount of work for gaining 200w over the drop in 36v 800w brushed motor, 48v 1800w or even more powerful brushless motor. Can it be done? Absolutely! But I'm pretty sure even Helen Keller could see that it's not worth the hassle in the end.