One of my KLR650s came with a DID 520 O-ring or X-ring chain from the factory. EK is also a good brand. I use DID or EK chains. You can find some really cheap non sealed chains that will not last long. DID makes an X-ring model and an X2-ring model. Either one will work, but make sure you get a matching master link because the cross pin diameters are not exactly the same.
As long as the chain is a size 520 it will fit gen1 and gen2 KLRs along with a bunch of other motorcycles in the 650 size range. DID makes a non sealed, an O-ring and an X-ring sealed chain in the 520 size. All will work on the KLR650 along with other manufacturers 520 size chains.
The O-ring chains are sealed around the lubricated cross pins by O-rings and last about twice as long as a non sealed chain. X-ring chains are sealed with ribbed O-rings and in my opinion may or may not last about 10% longer than an O-ring chain.
The stock chain length on a KLR with 15/43 sprockets is 106 links. Chains are often stocked in a box with 110 or 120 links and cut by the seller to fit your need or you can cut it yourself with a grinder. The chain without the master link is 105 links and the master link makes it 106 links long.
Make sure it comes with a new master link.
Last edited by GoMotor; 07-02-2015 at 04:55 PM.