Yamaha SR500 520 chain conversion

I'm converting from 530 16/44 to 520 16/40. The reason for going to the 40 tooth rear is to lower the revs at speed. I don't do much city riding, so I think the taller gearing will be better. The reason for going to 520 is to save some weight, and the 520 parts cost less also, so a win-win situation. If you want to know more about chains and sprockets, here is a great article that covers the basics. http://www.sportrider.com/tech/146_0008_gearing/index.html

Here's a weight comparison:
530 16 front -7.8 ounces
530 44 rear -2 pounds 3.8 ounces
530 104 chain -3 pounds 12.5 ounces

520 16 front -6.7 ounces
520 40 rear -1 pound 12.7 ounces
520 104 chain -3 pounds 10.9 ounces (note: I ended up using 102 links)


Here is the new 520 with the old 530 front. I'm using JT sprockets listed for the XT500.


The spacing is a bit different between the two. The stock SR500 530 rear has a slight offset, looking at the backs of the sprockets here. The 520 is flat, so...


...using a longer XT500 spacer for the front sprocket. If you buy 520 conversion sprockets for the SR500, they will be a little thicker at the splines, so no need for a different spacer. You could also use a washer between the spacer and sprocket to make up the difference.

The old non O-ring 530 with the new RK X-ring 520. As shown here, the new chain comes packed in grease, so give it a good cleaning before use or it'll make a serious mess on the bike.

Mocking it up to determine chain length. The old chain was 104 links, so starting at 104 on the new one. I bought a 120 link chain, as I got a lower price than buying a 104, and it only takes a minute to shorten. Leave the master link off, and put the chain ends on the rear sprocket at about the 2:00 position. Remove the shocks since you'll want to deteremine chain slack at the tightest point, generally when the swingarm is level. Without the shocks, you can lift the wheel to the tightest spot.

With the smaller 40 tooth sprocket, 104 links is too long. Note the axle is all of the way back in the adjusters.

Now, two links flipped up, move the chain to where it would be with the master installed, and the axle is further forward in the adjusters with plenty of room to move back. Removing the two links moves the axle forward the distance of one link. So, 102 links is what I'll end up with to get correct slack and adjustment range at the tightest point. Now I have to remove the two links and finish the install.

Pics once done!