ok thank you. the only think i am worried about is losing the prop nut if i try to do the counter rotating props.
also do you think i could use a different esc? a cheaper one?
im looking at 27 bucks not shipped for just the motor and esc. it might be better to actually go buy 2 other motors and escs that match that are cheaper.
if i go that way should i get similar kv and size motors?
If you tighten stuff down well, you shouldn't lose a prop nut. If you're really worried about it go to the hardware store and get a nyloc nut for 10 cents in the correct size. That won't be coming off without a wrench.
I don't know that I'd want to try a different ESC. Not something I've ever attempted. You'd want to play around with it and make sure it actually spins up and matches the same speed as the other one.
If you can find a set of matching motors and esc's for less than 27 dollars go for it. I've bought lots of cheap junk and had more good luck than bad. And when something fails, it's only foamboard.
When you're browsing for alternate motors weight is probably the most important thing to look for. Aim for something 25-60ish grams apiece. If the KV isn't super high, or super low, it'l probably do the job.