In this article I only describe my own approaches. I do not give any warranty that my data is correct.
Working on your motorcycle is at your own risk!
In case of doubt please contact a qualified workshop.
You can prolong the lifetime of your chain by constant maintenance, but eventually you'll need to replace your chain drive. If doing that, you replace chain and sprockets at the same time. In this article I describe, how I replace those components on my KTM 690 Duke. Before starting to work on the motorcycle, the correct replacement parts are needed. A look into the instruction manual of your bike will help you.
In the chapter "Technical Data" of my 2015 Duke 690 I found the following information:
Chain - 5/8 x 1/4" (520) X-Ring
Secondary transmission - 16:40
This means that my replacement chain has to have the same specifications as described. Most dealers (online or offline) already suggest the correct chain, if you state your motorcycle. In that case you only have to worry about the linking of your chain and maybe the color. But you should recheck the dealers proposal, just to be sure.
The type of linking for your chain is an important decision. Mainly you can choose between an endless chain or a master link chain (clip or rivet). From factory my 690 Duke had an endless chain installed. The drawback from this chain type is, that you have to disassemble the bikes swingarm to replace it. Since this is too much of an effort for me, I decided to replace it with a master link chain. You choose the type of master link according to the power of your bike. In my case a hollow rivet master link is advised.
Regarding the secondary transmission I need a 16 tooth front sprocket and a 40 tooth rear sprocket according to the instruction manual. Similiar to the chain you should get the correct sprockets suggested by your dealer, if you state your motorcycle. But double check, that the quantity of teeth and the dimensions of the sprockets are correct.
After getting the replacement parts you might also need a chain tool to break the old chain and rivet the new one. I got myself the Kellermann chain tool for that. With this tool I can break chains and link them with a hollow rivet master link. To rivet solid rivet master links you can get an additional adapter for this tool. In the following Youtube video you get a good impression of how to work with this chain tool:
Besides that you need the usual tools like motorcycle stand, ratchet and torque wrench for the upcoming procedures.
Replacement of the chain drive
To get to the parts that need replacement, you have to remove the chain protection and the front sprocket cover.
Removing the chain
If you don't have a clip master link chain, the chain has to be broken to get it off your bike. For that I used my chain tool. It pushes the rivet through its chain segment which allows you to open the chain.
After breaking and removing the chain, the front and rear sprocket can be replaced.
To take off the front sprocket you have to remove the nut. Don't forget to put your bike into gear. After taking off the front sprocket you have enough space to clean up the whole area.
The new front sprocket is placed onto the shaft and is secured by the nut. Use the torque and screwlock prescribed by KTM.
To replace the rear sprocket you need to take off the rear wheel.
The rear sprocket is held by 6 TORX screws to its hub. After removing the screws, the sprocket can be taken off. You should clean up the mount, before installing the new rear sprocket.
On this occasion you can also check the rubber dampers of your rear wheel. After that you can install the new rear sprocket on its mount. Use the torque and screwlock prescribed by KTM.
After the rear sprocket is replaced, the rear wheel can be reattached to the bike. Now the new chain needs to be installed.
Installing the new chain
The master link chain is put onto the front and rear sprocket. To make the installation of the master link easier, place the chain like shown below on the rear sprocket. The teeth of the rear sprocket hold the chain in the correct distance to slide the master link in.
Before sliding the master link into the chain, it has to be greased very good. I got a pack of grease delivered with my D.I.D. rivet master link chain. The grease is put onto the rivets and the X-rings. After sliding the master link into the chain, the chain is moved to a position, where the master link can easily be accessed by the chain tool.
When the master link is in position, you need to press the side plate onto its rivets. This can also be done with the proposed chain tool. Don't forget to put the X-rings on before that! Note that the side plate has to be pushed just as far onto the rivets like all the other side plates of the chain. Don't push it too far or else the X-rings are quished too much and will wear off faster.
After attaching the side plate to the master link, the chain can be closed by riveting with the chain tool. The tool presses its arbor into the hollow rivet, which widens up so the side plate cannot get off the master link anymore. It is advised to use a torque wrench for this. If the torque is too low, the master link can open again (dangerous!). If the torque is too high, the arbor of the chain tool can be damaged. The instruction manual of my chain tool manufacturer proposes 20Nm for 5xx chains (my Duke 690 has a 520 chain). Don't forget to rivet both hollow rivets of the master link!
The main work is done. Finally the chain protection and the front sprocket cover need to be reassembled and the chain tension has to be set. I experienced that the chain grease from factory wears off really fast. Therefore you can already grease the new chain on this occasion.
The whole chain drive is now replaced and you can do a test ride. Keep in mind that new chains elongate more at the beginning so check the chain tension frequently in this early phase.