520 EXC cam seal questions

Discussion in 'Thumpers' started by stevecce, Jan 24, 2013.

  1. stevecce

    stevecce Adventurer

    Joined:
    May 11, 2010
    Oddometer:
    16
    OK, I have a 2002 520 EXC that I have converted to dual sport duty. It is leaking coolant and oil from the water pump weep hole. In researching this I see it is a relatively common problem. My questions are:

    Where can I get the seals and the carrier? Do I really need to split the timing chain? Where can I get a shop manual for this bike (I have found some for sale but not this specific model and year).

    I am mechanically inclined and I have a pretty complete set of tools.

    Thanks in advance!

    Steve
    #1
  2. Johnf3

    Johnf3 Long timer

    Joined:
    Apr 10, 2007
    Oddometer:
    1,072
    Location:
    West Texas
    Any KTM dealer can get these parts. You need the carrier, the two seals and the two orings. Get the dealer to press in the seals into the carrier. It is very difficult to get them pressed in straight and lots of dealers will do it for free if you buy the parts from them. No need to break the chain. The seal assembly slides onto the end of the cam shaft. There are how to's everywhere on the net.

    Make sure that when you slide the seals on you wrap the cam shaft with teflon tape or something that protects the seals from the groove in the cam shaft. Use a very thin coat of locktite 515 or 518 on both orings. Check the cam shaft for wear at the point where the seals contact the cam shaft. You can try and clean up the groove from seal wear with some emery cloth if it is very slight, or press the seals in a little further so they ride on a different part of the shaft. If it's really bad you have to replace the cam shaft.
    #2
  3. Droptarotter

    Droptarotter Long timer

    Joined:
    Jul 11, 2007
    Oddometer:
    1,305
    Location:
    Cloverdale
    The early RFS motors also had upgrades for the seal carrier and decrompressor.

    One upgrade was the seal carrier. The newer one was designed so you did not have to remove the rocker cover. If your carrier has a couple of 5mm ( I think) tapped holes in the carrier, you should be able to remove the seal carrier without removing the rocker cover.

    See if your decompressor has a bolt/nut through the cam gear for it's stop,


    If it does, you might want to upgrade to the later cam sprocket that has the stop cast as part of the sprocket.

    The bolt/nut setup was known to come loose.

    I found it easy to install the seals in the carrier, but I did purchase 2 extras just in case I damaged them.

    There is tons of info on these bikes on KTM talk.

    Cheers
    #3
  4. stevecce

    stevecce Adventurer

    Joined:
    May 11, 2010
    Oddometer:
    16
    Thanks guys! Very helpful!!
    #4