This applies to the '02 and and newer models only. Mostly from James Dean with some added information from jeb.

Drain the radiators. The drain bolt is an 8mm headed bolt with copper crush washer located under the left headpipe on the front of the motor. Remove the water pump cover and impeller to access the seal carrier and seals. The impellar may give you some trouble getting off even after you remove the snap ring. You just have to work it and it will come off.

Simply pulling the waterpump cover and impeller off is the quickest way to get at the seals and O-rings. The '02 and newer seal carrier, O-rings, and seals can then be removed with two m3x.5mm screws inserted into the carrier and pulling them outwards from the side. The carrier has 2 holes that are threaded for m3x.5mm screws. Purchase two screws 20mm or longer to have enough length pull on. Insert both screws and thread them in until they bottom lightly. Use pliers or visegrips to evenly pull out the seal carrier.

It is very important to clean the surfaces well before reassembly such that the O-rings will have a good sealing surface and the sealant bonds. KTM suggests using Loctite 515 which is very thin and flows evenly around the O-rings and mating surface.

KTM also recommends using all new WP seal parts (carrier, 2 seals, 2 orings) and install them using the KTM "bullet" tool, KTM part number 590 29 005 010 which is about $5 from www.cyclezonektm.com . You can wrap a piece of plastic, etc around the end of the camshaft before installing the seal, instead. The point is to avoid wrecking the seal on the sharp groove.

BTW, the inner seals are a VERY tight fit and it's very easy to mangle them trying to install them in the carrier. How do you get it in then? Contact Old Stroker. He has the 'TOOL' and he presses them in for individuals and dealers all over the US. Email him at OldStroker@sbcglobal.net

Some folks have good luck just replacing the orings and reusing the carrier with the existing seals.

The two orings are NOT identical on the 02+ bikes so take note of the size when removing them. Use an extra dab of 515 sealant on the back O-ring in 2-3 places to hold it in place on the carrier when inserting the carrier and seals back into the bike. The seals and carrier need to be inserted squarely and light side force(wiggle) helps, being careful not to pinch the O-rings. There is a small bevel machined on the head & rocker cover to help the installation. Put an extra dab of 515 at the sealing juntion of the rocker cover and head afterwards and let it set open overnight. This is the usual source of leakage. The coolant side(outer) O-ring does not always conform to the slight offset between the head and rocker cover and will weep slightly at the pinhole.

BTW, Don't overfill the radiator. The pressure rises much quicker with less air at the top of the radiator. KTM recommends setting the coolant level only 10mm above the fins (.4 in) inside the radiator. This may help reduce the cooling system pressure slightly.

Special tools needed would be the small metric bolts to pull the carrier, the bullet tool from KTM (if you go that way), small snap ring pliers for getting the WP impellar off and the Loctite 515 or some other brand of Anerobic sealer.