In order to take proper care of your KTM 690 Enduro it is advisable to learn how to remove and install air box. Bike on the photos is 2016 KTM 690 Enduro R, but everything is almost the same on all 690's.
1. First, remove the seat and plastic side covers.
2. Loose the reg/rec. Just remove the bolts and leave it dangling on the wires.
3. Remove air box lid.
4. Remove four little bolts holding the air box. Front bolts are easily accessible through holes on the plastic cover. One hole is behind reg/rec.
5. Unplug this hose. Remember how it was routed.
6. Cut the plastic tie holding air temp sensor wire and remove air temp sensor out of air box.
On 2008-2013 models air temp sensor is bellow air box.
6.1. Optional - to make more room, remove ECU unit.
7. Now only rubber boot is holding the air box to the throttle body. Pay attention here. On 2014-2016 models there are two hose clips, but only one should be loosened (not removed), the one marked in green. Leave the one marked in red.
This is easily doable while air box is still connected with throttle body, with screw driver, from side.
8. Now air box can be removed. Lift the rear of the air box, pulling the rubber boot off the throttle body, then twist it and pull it out.
9. Secure throttle body opening with plastic bag or similar, to prevent debris and dirt from entering.
When you finish what ever you were doing, follow the same steps backwards.
1. Apply some grease on throttle body, so rubber boot slides easily.
2. If you forgot how breather hose was routed, here is the picture.
3. Be gentle on hose clip holding the rubber boot onto throttle body. Make sure rubber boot is positioned well, then there is no need to tight it too much.
4. Also, be gentle on four little bolts holding the air box - they are screwed into rubber cushion elements, so don't over tighten them.
5. Very important - be very, very gentle with two bolts holding air box lid. Tight them by hand only!
6. Don't forget to secure air temp sensor wires with plastic clip.
If I missed something, please let me know!