Idle RPMs on 03 KTM 640 Adventure

Discussion in 'Thumpers' started by meat popsicle, Jun 15, 2004.

  1. meat popsicle

    meat popsicle Ignostic

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    Still breakin in the beast, just wondering if it should be idling above 1500. Seems a wee bit high to me and others but I am new to thumpers. I did not see the idle speed recommended in the manual, anyone know?
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  2. PASSMORE

    PASSMORE Just the last name...

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    Mine seems happy when loping along at around 1400 when idling... Pertinent mods to this might be the FCR41 carb? Don't know, but she idles well at 1400. I have a 01 640 adv...


    Michael
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  3. murgatroid42

    murgatroid42 Great Adventurer

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    My XR650L is a totally different animal, but spec is 1300 RPM at idle. It sounds high to me, but feels good pulling from that. So, 1500 RPM for your KTM is believeable.
    #3
  4. Mack

    Mack Gone, but never forgotten. RIP, Mack...

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    Mine idled a little high, and sometimes hunted, especially after hard braking, during break in, though I think it was a float height issue. You might need to tweak the idle mixture screw as well. (Are you planning to rejet, install the airbox sidescreen, and tweak the silencer after break in? You will end up tweaking all again.) I have turned my idle way down to enable engine braking on really nasty descents, and as long as I do not get carried away to the point that it tends to stall or engage the auto-decompression, all seems to be good. Cheers, Mack
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  5. Tim

    Tim Long timer

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    I would tend to go for around 13 - 1400, aim for just above the level where the auto decompessor makes itself heard (nasty clacking sound).
    #5
  6. markjenn

    markjenn Long timer

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    Anything from about 1300-1700 is fine. Mine gets a bit lopey under 1500, so I keep it there. Singles won't idle down to below 1200 like most bikes - the bangs just are too big.

    - Mark
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  7. meat popsicle

    meat popsicle Ignostic

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    I was worried that some modifications would void the warranty... anyone have experience with KTM on this? Auto-decompression... something to keep the motor from stalling at low RPMs? That kicks in below 1300 I presume. Hmm, new one to me, I'll search for info. Thanks for the tip KTiM.

    Mack, I would be interested in modifications that do not sacrafice efficiency for power. I have heard in some cases it is possible to improve effeciency and power together. The dyno curves posted by the silencer mfgs are impressive; what's the trade off in fuel efficiency? I am interested in efficiency because of long-range touring considerations.
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  8. Mack

    Mack Gone, but never forgotten. RIP, Mack...

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    MP, The more opinions and input the better, hopefully some of the others that have done the rejet and airbox mod can give their thoughts. So far I have run my bike in too many varying conditions to tell if there has been a change in MPG. Post mods it seems to be about the same, and I have run the tank 330 miles to the low fuel light on pavement.

    IMO, the weakest point of the LC4 engine is the airbox, it is just way too small and restrictive. I assume it is because of this small size, but whatever reason it is very picking about where and how it is opened up, too much, is just that, and can cause problems. Lucky for us places like Sommer, have done their homework on the dyno, and come up with pretty standard configurations that really seem to work.

    Once again IMO, the best bang for the buck, is the KTM side airbox screen sold through hardparts, and the KTM Hardparts SXC silencer. (There are some other nice aftermarket setups, and creeper did a great job of cataloging them in another thread.) You can even stick with the Supertrap, adding disks and if you so desire knocking out some baffles, some guys have been really happy with this setup. I do not really care for the Supertrap, but to be honest, the 6 pound weight reduction by replacing it, really does little good, as it comes off the wrong end of the bike. I am running a 165main, drilled slide, side airbox screen, snorkle in, and the SXC Supermoto silencer (Healthy sounding, but a tad loud.) This pulls so nice, the chain snatch & LC4 chugging is moved down to around 2000-2200 RPM, the vibes are reduced, and the engine is just stronger all around. It is very much improved on and offroad.:thumb

    For an 03 things may need to be a tad different. Your main will be a bit bigger, I would suspect just one step up. And Sommer recomends removing the snorkle on an 03 as well, but this may only be with the Akropovic, I am not sure. IMO, the 03 high flow motor is setup more for European street use, I would be carefull not to move the powerband any further up, rpm wise. If you can find a good shop using an EGA to set jetting on a dyno, that really worked well for me, allowing the leanestvproper jetting possible, and thus good mpg. IMO, a lot of the seat of the pants, plug reading jetting of LC4s comes out on the rich side, but without and EGA, too rich is better then too lean. Hope this helps some.
    #8
  9. Tim

    Tim Long timer

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    When I was running my '02 adventure with the hardparts airbox door, SXC silencer and rejetted carb I was seeing 13 miles per liter, which equated to a 364 mile tank range. With my change to the FCR and Akrapovic I have seen from 9.3 to 10 miles per liter, (my IMO works it out for me each time I fill up) and therfore my range has gone down to under 280 miles. I have seen other reports from people with an FCR saying that they have had better economy from the FCR (better efficiency?), thus I think that I must be running too rich on the FCR.
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  10. Velocibiker

    Velocibiker Adventure Antagonist

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    My '02 Adventure idle is set right at/near 1500. I do believe it states that in the manual somewhere. Maybe it's in the factory repair manual??

    Anyway, mine is decanistered, rejeted, airbox mod and added discs to S'Trapp. If I go much lower, it has a tendancy to stall when cold. Any more and it just seems overkill and I like the engine breaking a low idle provides.
    #10
  11. creeper

    creeper Still alive...

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    Hi gang!
    As the engine breaks in, the idle speed will increase. You will need to adjust it occasionally as this occurs. it takes about 2000 miles for the engine to completely break-in and the idle to stabilize... or at least mine did.
    Like Velocibiker, my personal preference for idle speed is 1500 to 1650 RPM when the engine is at operating temperature. Substantially below 1500 RPM and the auto-decompression mechanism starts to "rattle".
    My LC4 is a '03 MisAdventure with a re-jetted and slide-drilled BST40, a "breather" side cover of my own design and a Supertrapp IDS2 with quiet core and 10 discs.
    My bike makes 300 HP at the rear wheel and does 5th gear roll-on wheelies :poser
    Creeper
    #11
  12. Mack

    Mack Gone, but never forgotten. RIP, Mack...

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    Boy is BlownCJ going to be pissed when he finds out! Hey, I thought only the KTMtalk bikes did 5th gear roll-on wheelies? I remember now, they do them in 6th gear....... Glad to see you back Creep.
    #12
  13. ktmnate

    ktmnate Long timer

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    Creeper, we missed you. Nobody has given me any grief.

    As for my Idle, it's 1500rpm. I have the hardparts air-box cover and still have the snorkle in. I am still using the factory exhaust and carb that's been re-jeted.


    #13
  14. creeper

    creeper Still alive...

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    Hi guys,

    I was only kidding, you guys know an LC4 only cranks out about 80HP....

    Thanks very much Mack and Nate for the kind words. I'm sorry I have not been able to participate in the Forums as much as I'd like. It will be a few more months before I have the time to get "reinvested" into the group.
    Lately, I've had to actually work for a living :eek1... Christ, do I hate working for someone other than myself!

    I appriciate you rat bastards more than you can imagine... I'll try to pop in when I can.

    It may be a bit premature to mention this, but I'm developing a new business, scheduled to open in the fall, that will specialize in services for European thumpers and twins. Stay tuned to this channel for future announcements. :thumb

    Creeper
    #14
  15. Velocibiker

    Velocibiker Adventure Antagonist

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    Oooooooohhhh....AAhhhhhhh.....

    That just bites. Now we have to sit around here and just WAIT???? :hair
    #15
  16. ktmnate

    ktmnate Long timer

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    Creeper,
    you have to quit working and get yourself a suga-moma:evil . I got me one that just got a new Ducati that I must break in for her. Good luck with your business.


    #16
  17. ChrisC

    ChrisC Amal sex?

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    I can see it now; "Uncle Creepie's Euro Biker and Fern Bar"
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  18. creeper

    creeper Still alive...

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    Sorry Velo. Unless you're a bank manager and want to offer me excellent terms on a business loan, I'm afraid you and I will have to wait awhile for me to get the start-up and 6 month operating costs in the bag.

    Love and Kisses,
    Creeper
    #18
  19. creeper

    creeper Still alive...

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    You do realize that posts such as this will be promenently displayed on the shop wall ... don't you?
    To serve as a reminder that strange people are everywhere...

    Uncle Creepie,
    UCEBFB Inc.
    #19
  20. ChrisC

    ChrisC Amal sex?

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    As long as I get an invite to the grand opening, feel free to use any and all of my copywrited materials.... :beer

    CC
    #20