Help Troubleshooting a 640 Adventure that won't run

Discussion in 'Thumpers' started by DefyInertia, Jun 8, 2010.

  1. DefyInertia

    DefyInertia Saratogian

    Joined:
    Dec 1, 2007
    Oddometer:
    165
    Location:
    San Francisco
    2000 KTM 640 ADV R w/ 24,000 miles

    Current Status:

    Bike cranks, but will not fire (battery is strong)

    I started the bike on Sunday. It started no problem and was warming up for a couple minutes before dying all of the sudden. It sounded perfectly normal before dying very quickly (it was by itself in the driveway).

    I tried restarting it right away. It would fire a little bit, then die. It would then fire less, and die. It then woudl not fire at all and has not since (I've tried push/bump starting it, E-starting it, and kick-starting it about 30+ times total). I tried starting it with and without an air filter in place.

    Relevant Mods:

    Aftermarket carb installed by the previous owner (not sure of the brand off the top)

    Airbox is opened up (previous owner)

    LeoV can (previous owner)

    With these mods, the bike was running really great prior to this. Great power, off-throttle response, fuel mileage, etc. Always started right away...no issues.

    Other Impotant Info:

    Idle is around 1,800 RPM

    Gas tank is full.

    Bike generally starts without the use of the choke. A twist or two of the throttle prior to thumbing the starter is all it needs.

    I changed the air filter immediately prior to starting the bike and think this may be the problem/cause. The air filter had been cleaned, oiled, and placed in a plastic bag by the previous owner. It was super tacky and appeared ready to go.

    My theory is that the filter was too restrictive, causing an overly rich condition, causing the plug to foul....

    My Plan:

    Remove the gas tank

    Check the spark plug

    If the plug looks good, make sure all the fuel lines going to the carb are good/clear.

    Then, if needed, I will attempt to see if the carb is somehow malfunctioning (note: I know very little about carbs, but intend to learn. I do maintenance, mods, suspension, etc....but not much real engine/carb work (my other bike is a FI'd Yami)).

    What I need from you:

    Thoughts/ideas related to what the issue might be and opinions on my "plan"

    thoughts/ideas on how I can get up the carb learning curve (I have the ability and will, just not the experience or mentor).

    Also, since I have to remove the tank to check the spark plug, I'm going to have to reassemble everything to see if that's the fix, right? Any tips on streamlining this testing phase and/or making sure the carb gets fuel again once the tank is reattached?

    Thanks :ear
    #1
  2. cagiva549

    cagiva549 whats a cagiva

    Joined:
    Oct 10, 2004
    Oddometer:
    3,140
    Location:
    Cypress Tx
    Is the gas valve turned on . I dont think KTM uses the vacume valves like the jap bikes do but if so they are failure prone . Check and be sure there is gas to the carb . SEYA
    #2
  3. whereisgibson

    whereisgibson Been here awhile

    Joined:
    Aug 9, 2008
    Oddometer:
    194
    Mine won't start without the choke. Are you running too rich / have something broken in the carb? My money is on the carb.
    #3
  4. DefyInertia

    DefyInertia Saratogian

    Joined:
    Dec 1, 2007
    Oddometer:
    165
    Location:
    San Francisco
    Gas valve is ON. I also tried switching both valves to reserve.

    However, I have not determined if gas is getting to the carb but I know I need to. The fuel goes from the tank, to the fuel pump, to the carb and the hoses are not transparent...so what's the best practice for confirming the carb is getting fuel?

    the previous owner explained that with the current carb, two twists of the throttle prior to thumbing the starter creates the temp. rich condition needed for a cold start.

    I really don't think the bike is running rich in general as fuel mileage is pretty good and the bike pulls very hard....seat of the pants feels to be twice as powerful as my 08 DR650.
    #4
  5. cagiva549

    cagiva549 whats a cagiva

    Joined:
    Oct 10, 2004
    Oddometer:
    3,140
    Location:
    Cypress Tx
    Open the carb bowl drain screw and see if there is a steady flow of gas draining out .Also if it has an electric pump you should here it pumping when you turn on the switch . When draining the carb turn the key on and the pump should run . SEYA
    #5
  6. Pokey66C23

    Pokey66C23 Been here awhile

    Joined:
    May 20, 2008
    Oddometer:
    516
    Location:
    wetside
    I had a problem with the intake pulse line from the intake manifold to the fuel pump. The line had a crack in it at the intake manifold, the crack ran past the barbed nipple on the intake manifold. So the fuel pump was not pumping fuel, it had no engine pressure pulse to actuate the membrane in the fuel pump to move fuel through the one way check valve on its way to the carby.

    Symptoms: Multiple cranking required on the e-start before I would get a weak start.

    Good luck. Mine is an 03 and I have never had any other problems other than wearing out rear tires at an alarming rate. :lol3
    #6
  7. DefyInertia

    DefyInertia Saratogian

    Joined:
    Dec 1, 2007
    Oddometer:
    165
    Location:
    San Francisco
    Just got home from work and did the following.

    • Sprayed some carb cleaner into the intake (air filter is removed)
    • Thumbed the starter
    • Bike started!
    • Then died

    Looks like I have a fuel to the carb problem.

    That took about 2 minutes...getting closer...going back to the garage to investigate fuel supply issues.

    This carb shit ain't so hard :D

    Good to know
    #7
  8. meat popsicle

    meat popsicle Ignostic

    Joined:
    Feb 9, 2004
    Oddometer:
    14,356
    Location:
    Circumlocution Office of Little Dorrit
    Any luck with the troubleshooting threads littered about the 640 Index?

    If you get nowhere, do you know about Scuderia West? I'll personally vouch for them; they are a good shop.
    #8
  9. wrk2surf

    wrk2surf on the gas or brakes

    Joined:
    Dec 16, 2007
    Oddometer:
    7,782
    Location:
    THE exact center of California/Bass lake/Yosemite
    pull your fuel line off the carb and try to start it to see if your pump and fuel are working first.. then you know to pull the carb for a look see..
    #9
  10. Chad M

    Chad M A full head of air.

    Joined:
    Jan 11, 2006
    Oddometer:
    906
    Location:
    N49, W4
    Did something find it's way into the idle circuit while idleing before it died? I've never tried it, but I wonder if it would start with the throttle held partially open, ie: on the main instead of the idle circuit.

    "the previous owner explained that with the current carb, two twists of the throttle prior to thumbing the starter creates the temp. rich condition needed for a cold start."

    It sounds like your carb could be an FCR-41.

    Check out this thread... http://www.advrider.com/forums/showthread.php?t=43819 And then search from there.

    Good luck!
    #10
  11. DefyInertia

    DefyInertia Saratogian

    Joined:
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    Oddometer:
    165
    Location:
    San Francisco
    Pulled the 17mm bowl plug...some fuel came out but that was about it.

    The tank is now off but it appears that I need to continue my reading/education on carbs so I can figure out what the problem is. I want to know more before I start removing jets etc. and cleaning everything. In the meantime, I have a couple questions.

    (1) when the bowl cap is removed and the petcock is open, should fuel dump out?

    (2) when the overflow scew is open and the petcock is open, should fuel dump out?

    I have no fuel leaving the carb in both of the above situations. Does that tell me anything?

    Based on what we've learned today, what kind of things would cause the bike to stall all of the sudden like it did? Clogged pilot jet?

    Oh by the way, it's got the Keihin FCR on there....

    Thanks again

    No sir, unless I missed something. I spent about 3 hours reading on Sunday and another couple hours reading Monday night before posting this today. I know this isn't a unique issue...I'm just not familiar with carbs. Sorry....I'm usually pretty resourceful but when you're lost, sometimes you don't know what to look for. Don't worry, I'll be giving advice on this shit a year from now after owning this bike for a while (just got it last month). :D

    Scuderia is a great shop...I buy parts/supplies from them every now. I lived half a block away for quite some time. :thumbup

    I don't follow

    I tried starting it at all different throttle positions. But yeah, I'm going to take a look at the pilot jet.

    Yes its a FCR. Reading the thread you posted now. Thanks. :clap
    #11
  12. bmwktmbill

    bmwktmbill Traveler

    Joined:
    Jul 16, 2005
    Oddometer:
    5,610
    Location:
    Traveler
    Reread what Works to surf said. First remove the fuel line at the petcock and open it, does gas run out, reconnect the fuel line and follow W's to Surf's instruction to check the function of the fuel pump to carb.
    Does it run?

    Have you removed the fuel tank to make sure you have spark?
    If not do it.

    If you don't find spark tighten the cap on the wire, check the main fuse(near the battery) and tighten the contacts to each leg with a needle nose, next tighten the connections at each battery terminal.

    Try it again.
    Does it run?
    It better!!!
    bill
    #12
  13. DefyInertia

    DefyInertia Saratogian

    Joined:
    Dec 1, 2007
    Oddometer:
    165
    Location:
    San Francisco
    Seems like it's most likely that my float needle is gunked up and stuck. I'll be investigating.

    The plug is fine. The bike runs for 3 or 4 seconds on carb cleaner :)

    I forgot to mention that after confirmed the spark plug was fine, I did the following:

    • Opened the overflow hose screw
    • Liquid drained out of the overflow hose and then stopped

    Hmmm...so then I did this:

    • Pulled the petcock to main fuel line hose
    • Fuel dumped out so I closed the petcock
    • Pulled the fuel line off the carb and reopened each petcock, one at a time
    • Fuel dumped out
    #13
  14. bmwktmbill

    bmwktmbill Traveler

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    Oddometer:
    5,610
    Location:
    Traveler
    Defy,
    You are close.
    The carb comes off and up through the frame rails with all the cables attached, unhook the fuel line and the airbox connection and anything else you dont like, clear the way, be gentle, it's a bitch, the bowl screws can be f'n tight so lock on with a vice grips, needle nose if necessary.

    Sounds like something's plugged, main jet idle jet, fuel screen in carb intake pipe(this screen I have not ever personally seen but they say it is there).

    Have fun, rag off the opening between the rails to catch small parts, I stick a piece of board across to make a work station, watch out for the idle fuel screw o-ring and spring, idle jet unscrews, main jet unscrews and is slotted for position. Bowl gasket is good for life. Easy on the carb cleaner, use air.
    bill
    #14
  15. Laromonster

    Laromonster Vesperado !

    Joined:
    Jun 28, 2004
    Oddometer:
    1,501
    Location:
    Sviland
    fuel pump aint pumping,check vac line :1drink
    #15
  16. DefyInertia

    DefyInertia Saratogian

    Joined:
    Dec 1, 2007
    Oddometer:
    165
    Location:
    San Francisco
    Success!!!!!!!!!!!!!!!!!!
    It was in fact the float valve. Bike runs great again. Y'all rule! :clapping
    I didn't replace anything and there was not much more than some crustiness on the valve and its housing but I was able to clean it to the point where it would just fall out if I was not holding it.
    Here are some pics:
    There she is....
    [​IMG]
    Before cleaning
    [​IMG]
    After (not much difference)
    [​IMG]
    Hopefully I don't have to see it again for a while
    [​IMG]
    Once again, thanks for all the help. I have learned a ton...carbs are not longer completely foreign to me and I know a lot more about my new to me KTM.
    I think in the future I am going to shut off the gas and drain the bowl if I know the bike is going to sit for more than a week. Hopefully that will prevent this problem from happening again or at least extend the interval.
    :thumbup :thumbup :thumbup
    #16
  17. 666

    666 Agnostic and Orange

    Joined:
    Feb 23, 2005
    Oddometer:
    1,327
    Location:
    San Francisco, CA
    btw. This is FCR carb, not stock.
    I installed it few months before selling this bike to Defyinertia.
    It was best improvement to the bike, and I got better mpgs than with the BST, at least for my riding style.
    #17
  18. DefyInertia

    DefyInertia Saratogian

    Joined:
    Dec 1, 2007
    Oddometer:
    165
    Location:
    San Francisco
    Never had the problem again....bike always starts first kick.
    #18