640 hiccups

Discussion in 'Thumpers' started by gunnerbuck, Jan 10, 2006.

  1. gunnerbuck

    gunnerbuck Island Hopper

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    This is my first post of probably many : I am wondering if any of you 640 owners have experienced the following problem. I have an 03 adventure and every once in a while, usually out on the highway, the engine cuts out for a split second. This usually happens at around 5000 r.p.m and more frequently when conditions are wet. I first suspected water in the fuel and maybe the engine digested a droplet so I drained the carb a few times to put an end to that theory. It did it again the other day and it almost seems like an ignition cutout for a fraction of a second. Oh yeah once again it was wet [when hasn't it been in the last month in this part of the world]. The spark plug is fresh so the next thing I'll check is for any rubbed wires which could be shorting out. I'll have a good chance to do this when I have to repair the warranty repair on the leaky valve cover. [This seems to be a chronic problem with some 640s]. Anyways this hiccup is hard to diagnose because of its infrequent nature. Any ideas?
    #1
  2. LoFlow

    LoFlow Long timer Supporter

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    This happened to mine one time only. Under acceleration it just shut down and I pulled off to the side of the road. Hit the starter and away I went, no problems since.
    These are very difficult to diagnose for sure. You may try to, at idle grab and lightly tug on all the wiring harness, relays, and modules you can see. Sometimes poor electrical connections or components will surface. At least when the problem gets worse it gets easier to find. good luck
    #2
  3. 2 SPOT

    2 SPOT bring the rape whistle

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    yeah sure sounds like electrical issue, difficult to diagnose. pay special attention to the wires comming out of the case for the,, stator? i had a problem once on my old KLR where the front sprocket/chain made contact once in a while with those wires.
    #3
  4. laramie LC4

    laramie LC4 flying something...

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    have you removed your smog cannister yet?

    if not, it could be the problem. what happens is that you end up pinching the plastic tubing that runs under the seat going back to the cannister. when this happens it creates a vapor lock of sorts and cuts off the fuel. i had this problem with my bike when i first got it, it would just randomly die. once i removed all the emissions crap it went away.

    do a search, there are several posts here and at ktmtalk about this mod....

    good luck,

    laramie :stoned
    #4
  5. meat popsicle

    meat popsicle Ignostic

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    Good suggestions already above. I would just add that if a shop is doing your valve cover "gasket" under warranty - read over creeper's how-to thread before you go. You might be convinced to buy a tube of that new and improved liquid gasket spooge that he recommends and give it to the shop doing your bike. That way you get the job done for free (hope they do it right) and the good spooge in there. :thumb
    #5
  6. creeper

    creeper Still alive...

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    Hi Gunnerbuck,

    Welcome to the asylum.

    Aside from the areas to look at that are already mentioned, check the vacuum hose from the right side of the intake manifold to the fuel pump. In the past, this piece has kinked due to length and routing and the subsequent loss of vacuum renders the bike temporarily out of gas.

    Also, when you remove the fuel tank to check and reroute the tank vent hose, check the spark plug cap to make sure it’s screwed on tightly to the high tension lead. It’s common for the lead to be a bit chewed up and sniping off 3/8” and screwing the cap on tight can restore a poor connection to its original sparkly self.

    Thats all folks,
    C
    #6
  7. gunnerbuck

    gunnerbuck Island Hopper

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    Thanks for the advice, this gives me a few more things to check in trying to fix the problem. Already had the warranty repair done about 8 months ago on the leaky valve cover, now its up to me to fix it right. I dont know the sealing product they used at the dealer, but I've got a tube of Yamabond 4 that I was going to try .Before I do, I'll check out creepers thread to see what he used.
    #7
  8. hawkster

    hawkster Adventurer

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    Gunnerbuck, I had exactly the same problem and took awhile to find. Under the seat near the battery I had a connector with 4 wires, two orange. One orange wire was disconnected/intermittent and possibly from time to time hitting the negative battery terminal. I soldered the orange wires together and problem solved. I got pi$$ed when it died on me 4 times on the way home at 50 mph in traffic. Most time it would start right up, or just lose power and regain again in a few seconds. Wires soldered under tape in pic.

    [​IMG]
    #8
  9. meat popsicle

    meat popsicle Ignostic

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    need an internet host for those pics hawkster. then [​IMG] will make them show up.

    for $40 a year smugmug will host all the pics you want; pretty damn good deal and a nice site (disclosure: the guy who pays for this site owns it so you'd be givin him some biz; nice payback eh?).
    #9
  10. neepuk

    neepuk Such a drag...

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    Photobucket.com is free and soooo easy even I can do it.:typebut if you got a few bucks, smugmug is way better!
    #10
  11. gunnerbuck

    gunnerbuck Island Hopper

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    Thanks Hawkster, that could narrow down my search considerably. I'll go check those connections right away. :norton
    #11
  12. gunnerbuck

    gunnerbuck Island Hopper

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    The only wires I see near the neg. battery post go to the rectifier and they check out o.k. I guess this was to easy . I wonder if Noah is building, man is it ever raining outside. On the weekend I'll do a little more wire tracing, hopefully I'll find the problem. Thanks again for the tips.
    #12
  13. Castleman

    Castleman Guest

    My LC4 did the same thing. Over a couple of weeks time, it happened more and more. My problem was the "pulser coil" under the right cover was giving up and eventually failed. It also could be the ignition key, the next time it dies on you, reach up and turn the key off and then right back on again.

    Good luck
    #13
  14. potatoho

    potatoho Cheese and Rice!

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    Check the kill/run switch on the bar as well.
    #14
  15. gunnerbuck

    gunnerbuck Island Hopper

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    This looks like it could be the culpert as my vent line had been rerouted and pinched under the tank . I think this happened while the bike was in the shop for warranty service.{ Thats a story in itself for a different thread} Anyways the smog cans days are numbered.
    #15
  16. Buckster

    Buckster Banned

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    Check your wiring under the fairing, there is a bunch that is sandwiched between the fairing support tubing and the plastic behind the instruments, a few wires wear through and short out in the wet, with a few vibes, causes just that problem. Once sorted they can be rotated back slightly so they no longer get sandwiched.
    #16
  17. gunnerbuck

    gunnerbuck Island Hopper

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    Thanks Buckster I still have the fairing off so I'll check it out. I went over all the wiring under the tank and seat yesterday and they looked OK. The only thing I could see was a pinch in the vent, whether it was enough to cause the problem I guess I'll find out. I just resealed the rocker cover so I'll give it a couple of days to cure before I test ride.
    #17
  18. gunnerbuck

    gunnerbuck Island Hopper

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    I checked the wires against the fairing mount tubes and could see the area your talking about. I spun the wires and could see where there was a little minor rubbing but the shielding is still OK . thanks again for all the tips.
    #18
  19. dagwood

    dagwood Banned

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    same thing. couple things to check. disable the clutch safety switch and pull apart the start button /kill button. clean and put some dialectric grease in there pop her back together. bet thats the culp.
    every once in awhile i do this as livin in the Great Nord Wet moister gets everywere.
    #19
  20. gunnerbuck

    gunnerbuck Island Hopper

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    Problem resurfaced in a big way today , halfway to Cambell River {200 km ride} my speedo starts going wonky, then the tach starts bouncing to 0 revs at cruising speed and the hiccups start. I kept my fingers crossed and continued on for an hour till the first light in C.R. forced me to slow up and then she died. I reached under the fairing and wiggled some wires then the instruments jumped to life and she fired up, And then died as soon as I turned the steering. I tried it again and made a gas station before she died again. I went over the wires and found the ones going into the keyed ignition switch were the culperts. I managed to start stall my way to Canadian Tire where I began teardown, pulled the fairing off and then pulled the Ignition switch assembly apart. Found two wires broken off their soldered terminals, one fresh and one had been loose for a while { the source of the original hiccup problem} . I bought a butane soldering iron {#4 I have 3 at home already} and soldered the wires back to their posts and put things back together . Pressed the button and she fired up right away, end of problem. I rode another 300 km without the slightest hint of hesitation, she ran flawless. Looking at the wires running into the switch I can see how they move when the bars are turned causing the terminals to wear over time, I may squirt a lump of silicone in there to help dampen the twisting effect and hopefully prevent any future incidents. Now I'm thinking about keeping the soldering iron in my everything kit.
    #20