I've got a K8, had stock setup (15t front, 41t rear, 630 chain). I replaced the chain and sprockets about 3 years ago (Feb-2004) with aftermarket parts ordered from the local Honda dealer; both sprockets were JT - Front was $22, rear was $33, cheap non-O-ring 630 chain was $53.
I didn't take very good care of the chain, hardly ever lubed it - finally got to the point where tightening it was good for about 10 miles, then had to tighten it again...
So I started looking online last week, comparing prices. Most of the prices were right in line with what it cost for the local shop to order (as mentioned previously in this thread). However, the folks at the local Honda shop were not real helpful with what I needed this time around, so I headed over to the Yamaha shop. They were more than happy to help. Prices were equivalent, and they said they could have the parts in the next day. Cool!
In reading many posts online here, I had been thinking of the 630 to 530 conversion, and decided to give it a whirl. The 15/41 630 setup has a 2.73 ratio. Closest I could get in a 530 was an 18/48 (2.67 ratio). I was wanting to gear it down a bit to reduce RPM's on the highway, so that sounded good. Because the front sprockets were only $22, I ordered a 17t and an 18t, along with the 48t rear. (Was going to get a 46t rear too, but at $40 each, one was enough for now. Was thinking I could swap out sprockets until I got just the right feel...) Chain is an RK 530XSO, 110 link. Had to cut down to 104 links. (As an aside: the 630 chain I just took off the bike was 86 links. To show how bad the chain was after 3 years of no lube, after I took it off the bike and measured, it was 64.25 inches long compressed, 66.5 inches long stretched! Yikes! Each tooth on the rear sprocket had two points from the chain-wear.)
Before swapping the sprockets/chain, I wanted to compare RPM's at different speeds. With the 15/41/630 setup, the bike spun in 5th at 70MPH, 5300RPM. With the 18/48/530 setup, 70 MPH in 5th is at 5200RPM. In 2nd, the 15/41 would hit 67 at redline (8500), the 18/48 got up to 70MPH at 8500RPM.
So not a whole lot of difference. I imagine if I put a 46t rear (giving a 2.56 ratio), it would drop me down to about 5000 RPM at 70MPH. Almost not worth the hassle.
One difference between the 530 chain and the 630 chain was the master link. The 630 had the clip, the 530 has rivets. I had to borrow a chain rivet tool from the Suzuki shop (spreading my business around, you know - actually it was a proximity thing...) I can't say I'm very comfortable with the whole rivet thing - it just didn't feel like it is on tight/right. I think I'll stop by one of the shops to have it checked tomorrow. All I can think about now is that link coming loose and wrapping the chain around the tire.
For reference sake, here is the part# info:
JTF331.15T - Front
JTR333.41T - Rear
EK630 - 92 Chain
JTF288.18T - Front
JTR284.48T - Rear
The 530 stuff went on without any additional spacers/washers/etc. All seemed to fit real nice. The 18t front sprocket was a little bit thicker than the 15t it replaced, but it fit real nice on the drive shaft.
Sorry for the long post - was trying to provide all the info I was looking for over the last few weeks in getting ready for my conversion/replacement. Hopefully somebody will find the info usefull.
I don't see any immediate benefit of witching to 530 if you've got brand new 630 chain/sprockets.
One of the other posts indicated that running a 530 setup was going to result in less HP lost due to the 630 chain and sprocket weight. Mine feels smoother now, but I don't notice any extra oomph. I'm attributing the smoothness to going from a non-Oring chain with over 2" of slack to a nice new tight O-ring chain. I imagine I'd have gotten more "kick" if I had gone to a different ratio, but then, I could have done that in 630 as well. If you're interested in changing the ratios, you'll just have more options in the 530.
If you're interested in making the swap, I'd wait until you need a new chain (or were interested in gearing up/down because you weren't happy with what your current 14/43 was giving you). Just my opinion...
On another note, I took the chain rivet tool back to the shop and asked them to come look at the Master Link because I wasn't exactly comfortable with my handy-work. They had a chuckle. I crimped the link too hard. The rivets looked ok, but one of the rubber O-rings was squished and sticking out beyond where it should have been. Fortunately, they had clip-style master links for the chain I bought. I'll be taking the rivetted one off and replacing it tonight.
If you're going to change from the 630 to the 530, be aware that many (most?) of the 530 chains come with the rivet masterlink. You'll need a rivet tool, or order the clip-style masterlink when you buy the chain.