1. eNewsletter Sign Up

790 Adventure R rear shock failure

Discussion in 'Parallel World (790/890)' started by [Art], Oct 19, 2019.

  1. TridentCO

    TridentCO n00b

    Joined:
    Jan 28, 2018
    Oddometer:
    5
    Location:
    Denver, CO
    Who is your dealer in Denver area? My rear shock just started leaking significant amounts of fluid as I approach 3K miles.

    #81
  2. Colorado Uli

    Colorado Uli Must I?

    Joined:
    Feb 6, 2006
    Oddometer:
    4,995
    Location:
    Ze Western Slope
    I purchased the bike from Sun Enterprises in Thornton, but having it serviced by my local dealer, Davis, in Montrose.
    I doubt it makes much difference because, as I'm learning, it seems that the instructions from KTM are to remove the shock and send it to them (WP?) for service. (Or possibly for replacement for another one? I don't know.)

    Best of luck with yours.

    Uli
    #82
  3. Teknik Motorsport

    Teknik Motorsport Tuner Super Supporter Supporter

    Joined:
    Feb 24, 2013
    Oddometer:
    61
    Location:
    Sydney Australia
    Stock rate is 95N, we made 10,10.5 and 110N springs in 210mm long specifically for the 790. All the shock failures in Australia seem to be going back to dealers for warranty where shocks are being replaced. From what I've seen and read, my opinion on the failures is either a surface finish issue with the production shock shaft or the rocking from the piston band and seal case bush being close, 11mm as George points out. KTM replacing shocks doesn't point to either the shaft surface treatment or the rocking. I'll do some more digging and see what I come up with.
    #83
  4. Jarrett2

    Jarrett2 Been here awhile

    Joined:
    Apr 11, 2018
    Oddometer:
    404
    Location:
    DFW
    What are the symptoms of the shock failure?

    Is it happening on both 2019 and 2020 models?
    #84
  5. gearheadE30

    gearheadE30 @LC8Adventures Supporter

    Joined:
    Jan 20, 2012
    Oddometer:
    2,205
    Location:
    Indiana
    Oil leaking out around the seal and onto the swing arm and catalyst. Often you smell the oil cooking off before anything else. You will also get some clunking from the shock once it loses significant fluid volume.

    I've not seen anything to say that 2020 shocks are better or different than 2019, but I haven't checked the part numbers.
    #85
  6. Jarrett2

    Jarrett2 Been here awhile

    Joined:
    Apr 11, 2018
    Oddometer:
    404
    Location:
    DFW
    Thanks for the info.
    #86
  7. Torque

    Torque Been here awhile

    Joined:
    Apr 4, 2006
    Oddometer:
    481
    Location:
    San Diego
    So I spoke with a couple folks about the R shock. Alex is fully aware of what is happening in detail but he is making the proper call and keeping it close to the vest as he is a WP service center. I would do the same thing. So I will say although Alex is aware this does not come from him.
    That said I am going to try to be respectful of a manufacturer that does great work but there is always a battle between the budget and how much engineering and testing can be done.
    With this in mind it looks like the shock has a couple of issues.

    Bottom line I am told the issues are side load and cavitation.
    So that is why they increased nitrogen pressure from the standard 145 to 150psi to 220psi. Unfortunately it is not omitting the cavitation.
    Keep in mind cavitation can do damage when severe and can create lots of heat. There are actually cavitation heaters.

    The adventure shock has been downsized to a
    46mm piston and body id.
    The stroke is 80 some mm.
    Compare that to a 990 that has
    50mm piston and body id and
    90 some mm of stroke. So you have a longer body for more oil more cooling from oil and surface and a longer stroke so the shock is not working as hard, and the stability of seal head and two pistons at 50mm holding the shaft centered.
    The 990 shock has 145psi or 10bar


    There are no fixes currently other than nitrogen psi and I think they are installing a smaller clamping shim I did not take notes. No real fix yet.
    So want to reduce cavitation reduce the damping. Allow the fluid to flow, but then you have insufficient damping.

    Also what is contributing to the initial harshness most are complaining about.
    Nitrogen level 220lbs ? I think minimally but contributor.
    Side load ?
    Piston size / orifice size ? Again I think minimal but will be looking at that piston later today to have a good look.
    Short stroke ? I think this has to be a contributor.


    Also keep in mind the 500exc has been downgraded to a small shock also. Not a race shock by any means. Husky is running larger shocks on the 501 you can pretty much take it to the bank the new husky adventure bike will have a larger volume shock?

    Follow the money.
    That is and will be the deciding factor.
    #87
    EvilSteve, gearheadE30, kzeb and 7 others like this.
  8. 1coolbanana

    1coolbanana Long timer

    Joined:
    Aug 25, 2009
    Oddometer:
    6,310
    Location:
    NW Sydney, Australia
    Thanks for the info :-)

    So do all the shocks from the factory have 145 psi and only rebuilt ones have 220 psi or do the later ones already have 220?

    Why do the tend to cavitate more?
    #88
  9. Velociraptor

    Velociraptor TrackBum Super Supporter

    Joined:
    Apr 17, 2005
    Oddometer:
    2,062
    Location:
    Pacific Northwest
    Have you seen any failures from rebuilt shocks? From your description, the rebuild still has a flawed design and the extra pressure only helps some or not at all. Also does the WP pro shock also have this same design issue?
    #89
    undingen likes this.
  10. Torque

    Torque Been here awhile

    Joined:
    Apr 4, 2006
    Oddometer:
    481
    Location:
    San Diego
    Originally the shock had lower nitrogen pressure then was raised to 220psi.
    Rebuilt shocks will last longer due to 220 psi if they had the lower pressures and the clamp shim mod if that is what it was that would reduce damping forces and reduce cavitation and help seals last longer. I also heard something about placing a larger O'ring behind the piston band as that would tighten up the piston keeping it from moving as much but also would reduce bleed and increase cavitation.
    Tangled web. Lengthen them and that helps. AdvRonski is lengthening his even more than the amount we have been doing. But it will help with side load no doubt.
    #90
  11. Fabricator

    Fabricator Hello Moto Supporter

    Joined:
    Sep 7, 2006
    Oddometer:
    220
    Location:
    Kent, WA
    Is the heat from the cat part of the cavitation issue (altho I thought there were reports of rear shock failure on decat bikes)?

    If not, this is unacceptable on a $15K bike...
    #91
  12. Torque

    Torque Been here awhile

    Joined:
    Apr 4, 2006
    Oddometer:
    481
    Location:
    San Diego
    Heat is created by the cavitation, the cat, and the friction of both reservoir piston and main piston. Heck the damping is heat in itself.
    #92
  13. Fabricator

    Fabricator Hello Moto Supporter

    Joined:
    Sep 7, 2006
    Oddometer:
    220
    Location:
    Kent, WA
    Understood, but was asking if the cat heat accelerates the failure... apparently (EDIT) the shock design sucks without the added cat/decat pipe heat.
    #93
  14. 1coolbanana

    1coolbanana Long timer

    Joined:
    Aug 25, 2009
    Oddometer:
    6,310
    Location:
    NW Sydney, Australia
    Part of the entry price for beta testers :lol3
    #94
  15. kubcat

    kubcat Been here awhile Supporter

    Joined:
    Sep 22, 2016
    Oddometer:
    880
    Location:
    Upstate NY
    @Torque - So if somone got a bike in early summer, its likely the lower pressure version? In your opinion, does this mean that all of those shocks are designed such that it is a matter of when, not if, they will fail? Maybe that means those of us lucky enough that our shocks haven't failed yet should still mod the shock, especially if also changing spring rate? If so, what course of action do you recommend? I was planning on buying your recommended progressive rate spring anyway. Should I remove the shock and send it to you for your recommended mods?
    #95
    TrailTrauma likes this.
  16. Torque

    Torque Been here awhile

    Joined:
    Apr 4, 2006
    Oddometer:
    481
    Location:
    San Diego
    Not sure when pressure changes were made.
    Destined to failure is relative to how many are out. Seems lots of them are holding up.
    Shock mod is theory although sound and does add travel meaning raises the bike.
    The mod advantage is not known regarding longevity as that has not been tested with few of them out there.
    So I will not sell something as a fix unless I know for a fact that it is indeed a fix. Just stabilizing the shock internally is all we are going after.
    The cavitation is another game and will take out a seal, whereas the mod addresses side load not cavitation.
    Will take a look at the piston to see if any improvement can be made later today.
    #96
  17. dtaski

    dtaski Been here awhile

    Joined:
    Sep 17, 2009
    Oddometer:
    128
    Location:
    Harrisburg , PA
    Just noticed mine was leaking fluid this morning. (3300 miles) Taking it to SOLID PERFORMANCE on Friday. Glad they are a WP Service Shop
    #97
  18. lbever

    lbever IAMX454

    Joined:
    Dec 25, 2003
    Oddometer:
    104
    Location:
    Clive, IA
    Shock failed on my 790R in Death Valley while doing the CABDR with a little over 6K on the ODO. Hopefully I will receive replacement shock from my dealer today. I have been told it is an updated shock but was not told what the updates are. I was also told by KTM that the part number between the 19 & 2020 is the same indicating it is the same part.
    #98
  19. Scourge

    Scourge Long timer Supporter

    Joined:
    Mar 25, 2014
    Oddometer:
    7,134
    Location:
    Lackawanna County, PA
    My dealer is also the NA WP authorized rebuilder... they preemptively did my shock before I picked up the bike. All I got was that it's some shim/spacer/valving changes but I was more interested in the shiny new bike than any kind of conversation at the time. I'm taking the bike back in for a warranty repair on something else next Friday and I'll try to inquire further. They ought to know specifics - since they are the ones doing all the work for everyone else.
    #99
    TrailTrauma likes this.
  20. lbever

    lbever IAMX454

    Joined:
    Dec 25, 2003
    Oddometer:
    104
    Location:
    Clive, IA
    [QUOTE="They ought to know specifics - since they are the ones doing all the work for everyone else.[/QUOTE]

    Conflict is also a WP service center and they are also doing the modifications.