As others have pointed out earlier in this chain, just convert back to the 530 chain from prior years. You will have no problem finding a gold chain and the sprockets aren't expensive.
My new 530 sprockets arrived yesterday, and a 530 chain (in gold!) arrives today. I can’t wait. My 630 chain bounces so much that I thought my rear suspension was falling apart. Is the rear tire mounted wrong? A shock fall off? Rear axle disintegrating? No. Just a super-massive chain that alternates between too tight and too loose, takes 10 miles to warm up and then flops around like a dying fish.
By the way, on the 1977 and 1978 CB750K, the sprocket combination that most closely matches our stock (15/41, or 2.733) is 17/46 (2.706),
not the 17/48 (2.824) that the 69-76 guys use. Our internal gearing is different.
Also, the 1977-78 swing arm is longer, so the chain has to be longer. I think the 69-76 chains are something like 102 links. I got a 110, and expect to delete a few when I install it. Does anyone know what the official link count is supposed to be on a retrofitted 530 chain on a 1977-78 CB750K? I figure it’ll be about 106-07.
