KTM 790 takes a few tries to start

Discussion in 'Parallel World (790/890)' started by doctorblanco, Sep 10, 2019.

  1. Vzuke

    Vzuke Been here awhile

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    I've been exploring all the different 790 forums (there are SO MANY!) I posted this on the "main" one?

    Mine had the same problem with a cold start (2 to 3 pushes of the starter button, didn't touch nothing else, and waited for the TFT show to end). And when I say cold start I mean first start of the day (August/September, HOT here in Tennessee).

    Heard on the other 790 forum about the Booster Plug solving the problem. I had one on my Triumph Tiger 800 but I didn't notice any change (hoping the bike would run a little cooler with it richer and stop the decel pops in the muffler) .

    Bought one for the 790, installed it, problem solved. Starts the first time like it should. Maybe KTM will come out with another "ECM flash" until then I'll stick with the boost.

    Now there is a sacrifice. I wasn't really checking my mileage on the bike but I do remember seeing 57.5 miles to the gallon. After the Booster I'm getting 52.9 MPG. Spirited Rider. Reminded me when I rejeted my DRZ400SM, was gettin 60MPG, after the jets 50MPG. BUT it was a lot more fun to ride!

    Here's how I hooked mine up:
    Boost hook up.jpg Booster comes with a temperature probe. You are supposed to keep it away from the engine heat. The Booster tricks the ECM that it's cooler than it actually is thus enriching the fuel. By the way I've always run high test in my bikes (if that would make a difference in starting).
    You can go to the Booster Plug web site and geek out on all the details of how it works.
    Think of it as a Danish for your Austrian bike.
    tail.jpg
    #81
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  2. braaap!

    braaap! Long timer Supporter

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    @Vzuke I got a booster out of curiosity... I've never had a problem starting my R... cold, hot, whatever. Thx for the install pics.
    #82
  3. Thumper Dumper

    Thumper Dumper Been here awhile

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    I'm thinking of building a small ice box under the seat to put the temperature probe in.:lol3:photog
    On a serious not I would love to see the difference the booster plug makes on a dyno.
    #83
  4. spartanman

    spartanman regret minimizer

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    I'm not willing to take a 10% mileage hit for easier starts. The bike runs great once started. Hmmm...install a switch to use the booster plug for starts then shunt it out for running?
    #84
  5. Thumper Dumper

    Thumper Dumper Been here awhile

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    It also helps with throttle response at lower RPM.
    #85
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  6. Tool.Nerd

    Tool.Nerd An idiot that owns a bike

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    I'll bet you could bribe your dealer to flash you an even worse fuel map and lean out your fueling even more, giving you another few % and some more green karma in terms of emissions, too!

    Meanwhile, I walked to school and installed some emissions controls once at a carpet mill. I'm combination with some other endeavors, I figure I have a negative carbon footprint I need to offset somehow.

    Joking, obviously. Lol.
    #86
  7. spartanman

    spartanman regret minimizer

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    If it ran like crap, I'd richen it up. It runs fine the way it is, imho. If the bike got 40 mpg, I'd still like it, but stellar mileage is another reason I love it. I don't have to carry extra gas like I did on the 990.
    #87
  8. Vzuke

    Vzuke Been here awhile

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    BOOSTER PLUG UPDATE:

    Nice day today so I took a long ride down a winding road with quite a few straightaways taking it easy and cruising about 60 miles an hour. Checked my data and it said I was getting 60.1 miles per gallon. Quite difference from the low 50's ripping up and down the twisty mountain roads.
    #88
  9. Thumper Dumper

    Thumper Dumper Been here awhile

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    During the run in period I recorded 72 miles per gallon but that was riding with friends who own BMW's :amazon, my average over the last 2200 miles has been 60 miles per gallon also with BMW buddies:-).
    The highest I've recorded was 52 miles per gallon for a tank of gas. I don't have enough mileage with the booster plug to tell yet but I don't expect it will change much.
    The most important factor in conserving fuel is the rider.
    #89
  10. SEK_Nick

    SEK_Nick Been here awhile

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    To the comments about 'a fix from KTM': I sincerely doubt we will see a 'fix' from KTM, because I think (with no evidence or data) that it is "working as intended." I think that the computer starts really lean, then as it "figures out the air" it works up to what'll start, then adjusts until smooth idle - for the sake of emissions.

    TL;DR: I'm pretty sure this issue is "as designed, working as intended."

    Honestly, it doesn't bother me too much. When people ask I just tell them "The computer is waking up and figuring out the air."
    #90
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  11. Tool.Nerd

    Tool.Nerd An idiot that owns a bike

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    If it is working as intended, then it is shitty engineering--emissions at startup is a shitty reason to compromise starter longevity and potentially strand a rider due to unnecessary battery drain.

    I mean no offense to the "just blip it and it'll be okay" folks but it's not a great design.
    #91
  12. Thumper Dumper

    Thumper Dumper Been here awhile

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    If it was "designed" this way why do only some bikes do it? As Tool.Nerd said this can cause starter motor and battery issues down the line. (Most probably when its out of warranty)
    My local KTM dealership has told me to bring the bike in and they will take a look at it, starting with a reflash.
    Due to the nature fault it may take awhile to solve but they are willing to look into it.
    #92
  13. SEK_Nick

    SEK_Nick Been here awhile

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    An excellent question, I can't say I'm enough of a mechanic to have an opinion about that. I'd certainly like my bike to fire on the first try as well, so it'd be nice if some kind of fix did come out.

    I think it's also interesting is not only is it "not every bike" it's also "not every time". Many days, my 790r fires up on the first throw just fine. I have not been able to determine any consistency at all; though it did seem to start on the first try more often at lower ambient temperatures. Anecdotal at best, though.
    #93
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  14. flange990

    flange990 Which way?

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    i left mine out in 5f degree weather all night and this morning it started instantly with no issue, i was surprised it started so well in this weather
    #94
  15. marchyman

    marchyman barely informed Supporter

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    Yup, sometimes it takes a few tries to stay started. When that happens I push the button again. It's not that hard.



    FYI it was not cold (68 °F) in the garage.
    #95
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  16. Tool.Nerd

    Tool.Nerd An idiot that owns a bike

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    Agree, not that hard, but sad nonetheless. I realize a 790 adventure is a bit higher performance than my Honda GCV160, but even the Honda GCV 160 that I've had for years cranks on the first try with minimal maintenance. What ye gotta worry about is how much you're going to trust something that doesn't start reliably -- and not starting on the first try for no reason means something flat out is NOT right with the fueling.

    Meanwhile, I've cheated and will keep cheating. The Boosterplug has worked successfully and turned mine into a "barely flip the starter and it turns over and it's running" scheme. Definitely a confidence booster when the bike actually starts up on the first try.
    #96
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  17. Toddv

    Toddv Been here awhile

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    Just wondering, do the 2019's have a distinct flare-up when starting and then stall or do they start and just rev up to the desired idle speed. My 2020 has a distinct idle flare up when first started cold or hot then it quickly drops back down to idle. Maybe a different map?
    #97
  18. Thumper Dumper

    Thumper Dumper Been here awhile

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    Mine does the same. Before installing the booster plug it would start up the same as you described and then instead of returning to idle it would just stall.
    #98
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  19. kubcat

    kubcat Been here awhile Supporter

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    Mine flares up. Just got it back from the dealer for a new fuel sensor, and they tried to recreate the starting problem but couldn't. He reset the APM? I think he called it? It's the data set that the ECU uses to autotune the bike. It did fire up on one when loading it in the trailer, and I have noticed that for me it's only a warm weather thing (>65) and only when the engine is cold.
    #99
  20. Toddv

    Toddv Been here awhile

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    Adaptive parameter memory maybe? Basically the fuel trims that adjust according to sensor data to keep the AFR where they want it and the idle adaptive strategy to compensate for variances from bike to bike and other little things that can throw it off. Hopefully that fixes it!