I know a 525 0r 530 cant fit in a 520 chain, but I have a 525 chain and found an ole front 520/15 that came off another bike. Now the teeth fit but there is a little larger gap because the 520 teeth are narrower, but has anyone done this before?

 

Still kinda of a squid when it comes to working on my bike, but from my hot rodding experience I would say that only bad things can happen! Off the top of my head I would worry about throwing the chain if you had just a tiny bit too much slack. Feel free to correct me if I am wrong guys, always like to learn more!