Hello im pretty new Yo-Yoing and am currently learning advance part 1 yoyo tricks. My bearing in my DM2 went bad and i would like to know what are some good brands for yoyo bearings. I would also like to know the different sizes of yoyo bearings. Does anyone know what size bearing a DM2 has. All answers will be greatly appreciated. 
Are you sure it went bad? What’s the problem?
I’ve had no issues with the stock bearing in my DM2. I chose to replace it with a Terrapin X Wing Cut bearing, which gave me improvement in my opinion. Other people have used different bearings with different result for them, ranging from good to bad. Mostly, it’s a matter of “Does this bearing work good for YOU in the yoyo you’re choosing to pop it into”.
The bearing might just need to be cleaned out. There’s plenty of videos on how to do this. It involves removing the shields and soaking and shaking the bearing in various commonly available solvents, including acetone, mineral spirits and lighter fluid. You may have also over-lubed the bearing. Cleaning the bearing will also resolve this issue.
But, if you want a new bearing, then don’t let me stop you. There’s many fine bearings to choose from depending on what you want and how much you want to spend and what kind of shape you want. The only thing you really need to keep in mind is that the DM2 takes a C-sized bearing, so any C-sized bearing will work, regardless of brand or model. Since all you have is a DM2, the only size you need to know is “C”.
The Dif-E-Yo Konkave(KK) is a bearing with a concave shape that keeps the string centered. The Crucial Grooved and Trifecta both use a groove in the middle of the bearing to force the string centered. The Trifecta seems to use a bit more curve I think. The CBC CenterTrac has raised sides but a flat center, which helps keep the string away from the sides but allows more movement for string layers. The Terrapin X Wing Cut bearings use a very slight concave which gives the advantage of free string movement but with most of the features of a concave bearing. The One Drop 10 Ball bearing is a flat bearing, as is the General Yo AIG bearing, and the YYF SPEC and YYJ Speed bearing AND the YYE bearings. Each bearing performs a bit different. It can be rather fun to figure out which bearings go best with a yoyo.
There are also A-sized bearings, which are in mostly Duncans, but there’s plenty of others that use this bearing. The B-sized bearing isn’t used too much. The YYJ Unleashed is the only one I’m currently aware of that is in production that uses this bearing. The next size is the C, which is the most common bearing. The D bearing is a small bearing. There’s a few that use this bearing. There is also a Euro-C bearing, which while close in specs to the regular C bearing, it’s not an exact fit. Be aware of what your yoyo requires. If you’re not sure, ask. I am working on a database that organizes this kind of stuff for reference. It’s raw and still being refined and added to. It’s an ongoing process.
I also have to ask: Have you put the full sized bearing in your DM2?
DM2 takes a Size C bearings, most yoyos these days take size C. I recommend the Trifecta Bearings. They’re very good in my opinion, Affordable price and long lasting
Unless you abuse them, it’s rare for a bearing to go bad. As noted by Studio42 there are a number of things to check/do before you replace.
Will any of those bearings increase the yoyo’s sleep time?
Maybe. The biggest thing affecting spin time is the throw. I’ve gotten bearings that I’ve taken from non-moving(due to being grease packed) to spinning for just over 45 seconds on a click through proper cleaning and doing a lubrication process I use. I don’t get such results on every single bearing, but I have on almost any kind of bearing, including YYJ Speed, YYF Spec, OD 10 Ball, KK, CBC CenterTracs, Crucial Grooved, Trifectas and other unknown brand bearings and other types of bearings including ceramics. So, I’ve managed to take the bearing out of the equation if we’re just talking about energy transfer and the potential.
Really though, the best thing you can do for yourself is practice that throw. I know, you’re in the advanced area as far as tricks are concerned. So am I. I’ve been throwing for nearly 18 months and my throw can still use some work. A good, strong, straight throw is your best way to increase spin times. Having a centered string on a crooked throw doesn’t do you a whole lot of good. Shaped bearings don’t help this problem, but they will help keep the string away from the sides. Having been to contests with ideal viewing positions, watching how flat and straight the top competitors are with their yoyos is simply amazing to view. That comes from years of practice.
So, the keys are:
A bearing in good condition that is properly cleaned of contaminants and lubricated or otherwise treated. I no longer advocate running bearings dry as I’ve had some issues with this, but others have not. I feel even a tiny touch of lube goes a long ways. I Terrapin X Dry Play treat all my bearings these days. Over-lubed and contaminated bearings can cause responsive play, which is not good unless you want responsive play.
A strong, straight, hard throw. No matter how clean and properly maintained the bearing is, and the shape of the bearing, without a good throw, the yoyo and bearing cannot perform as intended.