950 SE bogs after hard hits/jumps

Discussion in 'Crazy-Awesome almost Dakar racers (950/990cc)' started by CC Ryder, Apr 9, 2019.

  1. Yellow Pig

    Yellow Pig Allergic to asphalt! Supporter

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    Not necessarily. I had a Facet and a fuel pressure regulator set at 1.5, plus I adjusted the float level in the carbs and still got bogging in the whoops.

    The CV slides are vacuum operated, so there is nothing holding them up but a minuscule amount of vacuum pressure. One good jar from a jump and they drop, chopping off pressure.

    The few times I had the balls to not close the throttle and hit the whoops at full RPM/throttle I didn't get a bog, probably because there was more pressure holding up the slides.
    #21
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  2. AdvRonski

    AdvRonski They call me......Ronski

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    2 things here. First, in my experience 1.5 psi is still too high to stop flooding from High G-force situations, and second, the carb slides in these carbs are almost completely horizontal, which makes it very unlikely that they are affected by G-forces. And thirdly, the vacuum-applied force is quite significant, considering the large diameter of the pistons of the carb slides.
    #22
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  3. mountaincadre

    mountaincadre Long timer

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    I have a facet plumbed on my 950A with a fuel regulator and 1 psi is what it's set at, anything less and it cuts out about 85mph, anything more and it's to much fuel.
    #23
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  4. CC Ryder

    CC Ryder Adventurer

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    Thanks everyone! I just order the Holley regulator. Thanks for the link! I've thought about re-installing the OE pump just to see.. I may still do that. I also plan to check the float levels.. and see how the carbs are set up.. I think its tuned well, as it absolutely rips! But, I want to know how things are looking and what jets and needle positions are etc. It's gonna be a couple weeks before I have time to touch it though.. Prepping the 990A for a Southern Utah/Grand Canyon trip first.
    #24
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  5. singlewideteamusa

    singlewideteamusa Adventurer

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    For what it's worth...
    Had the same issues with my 950, burbling and loading up over rough terrain so I installed a vacuum pump and it solved the issue for me.
    #25
  6. Off Road Ryder

    Off Road Ryder Long timer Super Supporter

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    Interesting that everyone has been through the same issues. after going the facet/regulator direction, I finally found that the dr bean kit and lowering my float levels did the trick. Bike runs like a raped ape with zero bog on any jump or whoop section.
    #26
  7. Whodatschrome

    Whodatschrome Long timer

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    Isn't factory recommended float height 15mm? What did you lower yours down to?
    #27
  8. bemiiten

    bemiiten League of Adventures

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    Raising the floats / lower the fuel level in the carbs worked on my SE when I experienced the same issue you describe. It didn't completely eliminate it, but it's much better. I'll update later what I set them to.
    #28
  9. Navin

    Navin Long timer

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    I did all the above then even added 39mm FCRs and still it would load up and make a mess of throttle connectivity . I was at the end of my time racing with it anyway but skimming whoops was 50/50 and no fun having it do that in third or fourth gear in SNJ sand whoops during a race or DS event.

    Somewhere in here way back are my posts detailing my experiences with it. The regulator did nothing. I ran vac operated fuel pumps and had my jetting dialed with the box, with pods on CV
    s and pods on the FCRs.
    #29
  10. oldfuddy

    oldfuddy Long timer

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    With 4 SE’s all seeing 90% or more off road and two I raced in scrambles and GTs against little bikes, I had my fair share of trying to cure the infamous “bog”. Here’s what I found out… no two 950’s are alike and I’d offer there’s probably not two bikes in this whole thread set-up the same. Different float heights, different jetting, exhaust, vent line set up, vent line lengths, closed air box, open air box, snorkel, prefilter, paper filter, oiled filter, TPS, air jets, H2W, baffles in, baffles out, 2-2, 2-1, different riding altitudes, etc… and ones description of whoops is different between riders. Some describe whoops as getting the bike airborne, others describe whoops as swallowing the bike. Bottom line in my experience, there’s no one sure whoop fix cure for every bike. If you got yours sorted and it works for you, great. Doesn’t’ mean your fix will work on someone else’s bike. Doesn’t mean your fix is wrong either. Dialing these engines in is an art and there’s dozens and dozens of great combinations with each factor positively or negatively impacting another somewhere in the RPM range. If it’s not the side stand switch, just gotta keep trying different things, many mentioned above, just do them one at a time. And for giggles, some bone stock OEM bikes (my ’09 SE) didn’t bog at all in the whoops.
    #30
  11. Boatman

    Boatman Membership has it's privileges ;-) Supporter

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    ^^^^^^^
    Exactly what Fuddy says. Ive got 3 SEs right now and a 950 Adv. Also owned 3 other SEs over the years.... NONE of them run the same or could be tuned to run like each other.
    #31
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  12. Zuber

    Zuber Zoob Supporter

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    I'll have to throw a Bull Shit on this. The CV slides on this bike run sideways. So, not effected by gravity.
    #32
  13. Zuber

    Zuber Zoob Supporter

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    I worked on a bike (not an SE) that had the same high pressure fuel issue. Some ingenious mechanic had fixed it by bleeding off the fuel pressure back to the fuel tank. He put a Tee in the pressured fuel line and ran a smaller hose back to the fuel line before the fuel pump. Very cheap, simple fix. It provided just enough 'head' to fill the carb at all times. Cost pennies.
    #33
  14. skuikka

    skuikka Been here awhile

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    Thats what I've been doing on two SE's. No moving parts, runs like a champ. Large enough return line keeps the pressure at the carbs equal to the pressure the carbs would see with no pump and with a full tank.
    #34
  15. ThirdUncle

    ThirdUncle More will than skill

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    Try riding with your kickstand inner nub hooked into the rubber loop hanging there when you ride. If you don't have the rubber, there are extras under the seat you could steal. Like so many things on this bike, it was put there for a reason.

    I had the same problem -- for months. Nearly had a few crashes, too. In the end, I think it was Fuddy or someone who suggested it was my heel pressing down the kickstand and cutting the engine when I leaned back and gunned it, or went over whoops. It was exactly that.

    Everyone said to disconnect the sensor, but I'm too absent-minded to remember to put the stand back up every single time, and that's an accident I don't need to have.

    Try that and report back.
    #35