the spokes are pretty strong on the roadmaster sx sport mountain bike.
my first build was on one and it was a very tight fit,i even had to cut and drill the frame to get it to fit right and my air cleaner still didnt fit. my rear wheel was warped(im not sure if it was before or after i put kit on)but i liked the bike,but was hard to put kit on it.
but once the kit was on,it ran good and i liked that the engine took up the whole v-frame space.
i bought a new bike: a schwinn delmar cruiser,a lot smoother ride. cruiser tires plus springy seat.i lot of room in the v-frame part,so much room that i had to make a mount for the engine.but no cutting or drilling on this one.the only down side is the spokes on this bike are not as strong as the roadmaster,but there holding up for now.good luck on your build. if you have any questions feel free to ask me.
i kept the roadmaster for a electric bike project i might do.