How many links in my Chain?

First of all I would re-think an o-ring option on a 125. My dealer told me it takes too much power from the motor. Second of all the oring rubbed the case of my bike behind the sprocket. Some people shim the sprocket out with a washer, but that seems a little risky to me. I just bought Renthal works chain and love it. You have to clean a non o-ring just about every ride, but that is part of the game I guess. If you do buy a new chain, it should come with a master link. I would just buy a 120 link and cut it as you see fit. Pretty easy to do!

It has to be an even number counting the master link. The master links are included with the chain. They also sell master links seperate, that's why you see a catalog number for just the master. So, you need to buy a 114 link chain and don't have to buy a seperate master link.

A chain breaker would be nice, too. The first time I bought a replacement chain, I spent about an hour with a dremmel tool cutting the extra links off. I don't think they're that expensive, you might pick one up for under $20.