A 40 year old chain is a paperweight regardless to how many miles are on it. The O-rings are sure to be hard and brittle, not to mention chain technology has advanced in leaps and bounds since 1981 and 630 is an obsolete size in modern times.
530 is cheaper, lighter, more energy efficient, quieter and more durable. The only reason to stay with 630 is if performing a period correct restoration, such as for a Z1 or Z1R.
What came first? The chicken or the egg? What oil is best? What tires are best? What chain size should I run? Always the same questions and same answers. I detailed my reasons for staying with 630 chain in another thread on this subject and haven't changed my mind yet. I stayed with 630 because it kept things simple for me. Is durability better with 530 chain? I don't know for sure on that one, because the only way to find out is to run a real world test on two identical bikes with one equipped with 530 chain and the other with 630 chain riding each in a similar fashion over an extended period of time. This could be done in a test facility, but I haven't read anything of the sort yet. I don't think I could ride a given bike and tell you if it had 630 or 530 chain on it. I certainly don't hear any chain noise from my 630 equipped KZ-1000. I either hear engine noise or wind noise depending on speed and rpm. I have adjusted my chain once at about 500 miles after installing it and I have about 2800 miles on the bike now. The adjustment is still good and I do take care of it. The actual weight of the chain is something I can't argue with because I have never weighed an appropriately sized 630 chain against a 530 chain. And even if the 630 chain is heavier how much extra torque/HP does it take to get that chain moving and keep it moving versus 530 chain? And does it take as much power to keep that 630 chain moving versus 530 chain? I get a bit skeptical when I hear the argument, well the factory went to 530 chain so it must be better than 630 chain. Is that really the case, or was it a cost savings factor? I could tell you some stories about a certain motorcycle manufacturer that made changes to things as simple as clutch cables under the guise of making them better, only to find out later on that wasn't the case. The changes were done simply to save money and it came back to bite them in the a** later on. The only down side to my keeping the 630 chain on my KZ-1000 was finding a chain riveter/breaker, but I took care of that.
Perhaps one day I will have a couple of hundred bucks I don't know what to do with and I will convert my KZ to a 530 chain and sprockets just to see what the results are. Based on what I read here I would expect wondrous results and a notable increase in speed and smoothness, with less noise and better gas mileage. Until I get that windfall I will be forced to plod along with my antiquated junky old 630 chain and sprockets hoping that they get me home from each ride. Such is the case of a retired person on a fixed income. But wait, now I know what to ask Santa Claus for!
Always the same questions and same answers. I detailed my reasons for staying with 630 chain in another thread on this subject and haven't changed my mind yet. I stayed with 630 because it kept things simple for me. Is durability better with 530 chain? I don't know for sure on that one, because the only way to find out is to run a real world test on two identical bikes with one equipped with 530 chain and the other with 630 chain riding each in a similar fashion over an extended period of time.
Now let's talk about the best oil......
Save your self the time Rick and just look at the HP ratings of the bikes using the smaller chains, some of them are on their way to 3 times as much power as our bikes . It's NOT a chicken or egg scenario, its simple metallurgy mate, Modern chains are made from better materials, have better lubricating characteristics, are definitely lighter and just make more sense, There's no problem changing them either, if you can change a 630 you can change any chain, you can by direct conversions from a number of places so it's a no brainer. It has nothing to do with the "best oil" argument. As Nessism said, the 630 is virtually obsolete on modern bikes, there's a simple reason for that.....
The following user(s) said Thank You: ThatGPzGuy, Nessism