790 Adventure R Suspension Mods

Discussion in 'KTM 790/890' started by windblown101, Jul 5, 2019.

  1. windblown101

    windblown101 Long timer Supporter

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    Given that I don't see a dedicated thread yet for suspension mods & tuning on the 790 Adventure R I thought I'd start one ! I'm sure as time goes on folks will be doing plenty of experimenting.

    After some discussion with my dealer about the forks and what could be done to make the forks even better the decision has been made to go old school - He will be converting the existing forks back to WPs previous style open cartridge forks. The adjustment range on the previous version offered much more tuning control of the damping. I'll be dropping the forks off on Monday for surgery.

    I'm leaving the shock alone for the moment. Being that it has to control a lot of wheel travel with a very short stroke we're going to leave well enough alone for the moment.

    What's everyone else doing if anything?
    #1
  2. Torque

    Torque Been here awhile

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    Good call and thanks for starting the thread.
    Put the damping back in both forks with mid valve piston in right fork. Just blows through the stroke otherwise.
    I tend to use the mid for compression and rebound. Right cartridge needs to be sealed as WP did some drilling.
    This gets you back to the open bath forks that were in production for many years. Believe it or not new tuning developments have been found only recently to bring that platform up to next level performance.
    So with the above you now have a platform to start the modifications.
    Have to get the compression valving close out of the box internally as there are no base valve adjusters. That is definitely doable but sometimes takes a couple shots on a new platform.
    The fork can work better than you would imagine.
    In fact it can perform as well or even better than the Kit fork in some parameters. Shock too as the kit shock is more bling than zing regarding design although if you went to 50mm that would definitely be a temperature advantage.
    If there is an aggressive rider that can put the 790R through it paces and give some feedback, preferably in San Diego I am looking for a lucky victim.
    Initially keep it at stock travel and it may or may not take two shots to get it optimum. If it is not the best adventure bike suspension you have ever ridden it will be free. If it is the best you have ridden, parts cost only, unless you put in an honest and detailed review on this site. Then it is freeeee. Keep in mind if you are considering this. Many times I order custom rear spring to my spec's and that takes several weeks to get made. I likely have the fork springs in stock if needed but WP is getting much closer to correct spring rates from the factory. (finally)
    After initial internal mods you can have bike back to ride. Should we decide to do a custom rear spring we can install it later when it arrives.
    Actually I am likely to purchase a 790R in a few months for personal use although we are bantering a Score Baja 790R race run. We have a Husky sponsorship but are they coming out with the 801?
    #2
  3. windblown101

    windblown101 Long timer Supporter

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    @Torque

    I saw the holes WP had drilled in the one side and am going to ask about that, thanks for bringing it up. Not sure if the plan was to plug or swap that part out. I'm not a suspension guy, I just know if the suspension feels good and doesn't do odd things. Apart from clickers and occasionally playing around with oil height or "drop in base valves" I don't mess with them much. As I understood it they will changing the guts quite a bit and be putting base valves in both sides with compression adjusters on the bottom just like the old style forks with rebound up top. However I was struggling to maintain compreshension as he went over the differences. When he was done explaining I was like "Sounds great! I'll drop off the forks Monday" LOL.

    I'm sure it's possible that a bit of additional internal tuning may be needed after the first round since while the conversion is not new to them making the conversion on the 790 is. ;)
    #3
  4. coloktmGS

    coloktmGS Been here awhile

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    Anyone know if the forks are truly the same inside as XCW XPLOR? Reason I ask is I’d like to try the MX Tech Lucky system and they have one for XPLOR already. Anyone tried it?
    #4
  5. AdvRonski

    AdvRonski They call me......Ronski

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    I am reposting the suspension work I did on my 790R, as it will probably get buried in the other thread for mods.

    I know most people seem to like the stock suspension on the R model, but I have found it too harsh on the chop and cross-grain desert trails here in Western Colorado. I decided to take a look inside of the forks and see what improvements could be made. With the Xplor forks, the left fork leg controls the compression damping, and I felt there was too much high-speed damping there for my taste. I pulled the left leg, and drained and measured the amount of fork oil I removed, then opened up the base valve and measured the shim stack. I found that, sure enough, the final 3 shims that influence the high-speed damping were very stiff, being .15 mm thickness, while the rest of the stack uses .10 mm shims. I replaced those shims with .10 mm shims, and adjusted the low speed stack a bit, then buttoned everything back up. I put 625 ml of fresh oil in the fork, and checked the oil level, which came out to 110mm. I lowered it to 120mm, to lighten the spring rate up a bit, and finished up the re-assembly.
    The results are very impressive, with a much smoother ride through the choppy singletrack, and along with a Pirelli Scorpion Rally front tire, have made a dramatic transformation when riding this bike hard through technical terrain. The next project will be a shock revalve, and I would like to find a bladder kit for this shock first, but the reservoir on these shocks is smaller in diameter than most WP shocks, so that may have to wait.

    IMG_20190626_135235.jpg

    Well, after a successful revalve of the forks, I decided to take a shot at taking some of the harshness out of the rear shock. One of the first things I noticed about the new 46mm Xplor shocks is that they are much smaller than the 50mm PDS shocks of the 950/990 Adventure models. This is not good news, as the main job of the shock is to convert the excess energy of the vertical movement of the motorcycle into heat energy. With a smaller body and less oil capacity, there is a greater concern of overheating the oil in the shock, and losing it's damping ability pretty quickly. Another concern is the steep angle of the shock mounting, relative to the swingarm, which may make valving kind of tricky.
    On opening up the shock, I found that instead of 2 pistons of the same size, on the Xplor shock, the secondary piston is smaller than the primary piston, and curiously, the secondary piston has a small amount of float.
    IMG_20190629_134250.jpg
    After laying out the shim stack, i found that, much like the forks, there is some pretty hefty high-speed damping shims in the stack. I also found that this shock uses 12mm I.D. shims. like KYB shocks, instead of 16mm WP shims. My selection of those shims wasn't all that great, so I had to compromise a bit on my selection. Anyway, I reduced the high-speed damping, and also reduced the low-speed damping a bit.
    IMG_20190629_140404.jpg
    Then it was time to button it back up and bleed the shock with the vacuum bleeder.
    When I took the bike out to check my work, I was very pleased with the increased plushness over the chop, and it even worked better in the desert whoops, but I did find it bottoms too easily on g-outs. So, I ordered some of the shims I needed to hopefully correct that, and I'll try this again next week.
    #5
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  6. windblown101

    windblown101 Long timer Supporter

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    @AdvRonski

    Good stuff. Thanks! Maybe I'll get brave and dive in myself at some point.

    My orginal plans to have the forks modded have been put on hold for now. My forks were stolen off the tuners delivery dock. (along with someone elses cone valve forks and Tractive shock). :(

    My dealer and KTM have went above and beyond to assist. Within 48 hours they have sourced a replacement set that are in route as we speak, I should have them today or tomorrow. Since I have a trip coming up I've opted to keep the replacements stock for now due to limited time to test and tune before I leave.
    #6
  7. The_Eccentric

    The_Eccentric Gearhead. Supporter

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    Damn thieves. Your tuner needs some cameras back there. Maybe one us will spot your forks on eBay or CL.....
    #7
  8. windblown101

    windblown101 Long timer Supporter

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    I just finished installing the replacement forks a bit ago. I don't know how many favors my dealer had to call in to get me squared away so fast but I need to make sure he's on my Christmas card list.
    #8
  9. Bluetonguejak

    Bluetonguejak Pretend racer

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    What are the options to raise the suspension (other than Xplor Pro kit)?

    Any other shock available?

    Has anybody extended the original R forks (longer dampening rods, etc.)?
    #9
  10. Torque

    Torque Been here awhile

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    Easy to lengthen the forks with parts off a longer travel WP and can be valved to high level. Will have a look at shock specs and see if it is an easy extension. The issue with the 1090 was the swing arm had limited travel due to exhaust and chain protector. You would have to look at that as I do not have one here.
    #10
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  11. Torque

    Torque Been here awhile

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    KTM has not posted the shock specs as of yet and the parts guide I found does not show Reb shim size. Therefore not sure how much the shock can be lengthened.
    #11
  12. Rharr

    Rharr Been here awhile

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    The post above has the shock stripped down and looks to be a different beast then the old 990 stuff. Looking at the photos doesn't seem to be and thicken shim you can pull for a smaller on and gain a lot more travel.
    #12
  13. Torque

    Torque Been here awhile

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    Ya looks like you may get a few mm out of it but not lots. Keeping in mind 4mm equates to about 12mm at the wheel, regarding travel.
    #13
  14. AdvRonski

    AdvRonski They call me......Ronski

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    Well, after shock revalve #2, I'm liking the action in the gnarly terrain and rocky washes, but I am still having an issue with bottoming out too easily on g-outs. The smaller secondary piston on the Xplor shock seems to need much more aggressive valving than the big 50mm pistons of the 950/990 PDS shock. I also think a progressive-rate spring would work well on this bike, but no one seems to have many suspension options yet for the 790.
    The Hyperpro shock looks interesting, especially at less than half of the Xplor Pro offering, but I don't know anything about there performance and quality.
    hyperpro1.jpg
    #14
  15. turbofan790

    turbofan790 Adventurer

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    I know Touratech uses Hyperpro for their steering dampers and progressive spring kits.

    The pricing on the hyperpro stuff is absolutely incredible. It sure LOOKS good. For me, I think if I want an upgrade I'll hold out for the Tractive stuff. That sweet, sweet double-digressive piston sounds lovely.

    You absolutely seem to know your stuff... what are your thoughts on double digressive valving for off-road use? The company I work for uses Tractive's suspension for a road race application and we love it, but i've never experienced that type of valving off-road.
    #15
  16. Rharr

    Rharr Been here awhile

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    I know a few folks who run the hyper pro on their dr's with good results, last I heard. One of the guys (@mntdawg) is a avid rider and puts the shock though hell in the AZ rocks.

    Back in the mid 2000's when I would do a few track days, I would see quite a lot of purple springs on track bikes, not sure if it was a full shock or just the spring.
    #16
  17. Torque

    Torque Been here awhile

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    210mm spring I believe. Give me the id on both ends and may have a variable rate spring on the shelf. I most times order a 20% increase in rate. G outs, you are talking about lower speed compression bottoming?
    #17
  18. AdvRonski

    AdvRonski They call me......Ronski

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    Yes, it's a 210mm spring length, with a 95N/mm rate. I didn't specifically measure the ID, but I did slide a WP spring I had over the spring seat, and it fit the same as the 62mm ID springs from the PDS shocks.
    As far as the bottoming conditions, yes, it would be low-to-mid speed hits in washouts and jump faces. Landing from some air time and rolling whoops feel good, though. Weird.
    #18
  19. AdvRonski

    AdvRonski They call me......Ronski

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    Well, as far as I understand the term, digressive valving is usually what I am shooting for for my off-road applications. Meaning, fairly stiff low-speed valving to control the wheel movement near the bottom of the stroke, but lighter high-speed valving to allow the wheel to react quickly to sharp hits like rocks and square-edge obstacles. As to using this approach to the rebound side, as in double-digressive, I don't see where that is helpful. I have always considered rebound speed to be fairly constant. You can surely compress the suspension at different rates, but extension is pretty much dictated by how far the spring is compressed, and doesn't seem to need a complicated valving setup.
    I would like to see a system like the Fox RC3 shock, which along with the high and low-speed damping adjustments, also has an external bottoming adjustment for the secondary piston chamber.
    #19
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  20. TrailTrauma

    TrailTrauma Nemophilist Supporter

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    Speaking of suspension mods .. I think we just found our own avdrider.com suspension mod :)
    #20