LC4 Adventure Carb problems?

Discussion in 'Thumpers' started by ktmnate, Dec 9, 2004.

  1. ktmnate

    ktmnate Long timer

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    I love all kinds of skiing (only when I can do it). I don't thin it could have damaged the sparkplug. What I am now doing is one thing at a time. I want to know what it is that is causing this condition. Other than top speed, the 640 runs like a champ! I will keep the list informed.
    #21
  2. ktmnate

    ktmnate Long timer

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    I am almost suspecting the slide. I have had it apart again and inspected. It all looked good but didn't do much for top end. Everything looked like is was sealed correctly. It's gona take me several weeks to sort this one. I am only changing one thing at a time.
    #22
  3. ktmnate

    ktmnate Long timer

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    Ok, I played with the bike and got it up to 102 (On the GPS not IMO). Almost there. I just changed the jet to a 165 just to see what will happen. The problem was the ruber boot wasn't on all the way! It was off on the underside and I couldn't see it. Just another bone-head move! And my wife says I'm dangerous.
    #23
  4. creeper

    creeper Still alive...

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    I'm not going to say a thing... glad you found your problem. :thumb
    #24
  5. ktmnate

    ktmnate Long timer

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    Oh, that was only part of the problem. I put new grips on and man does that help. I swear the new grips gave it an extra 5 hp.
    #25
  6. Flanny

    Flanny Flanny-it-up!

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    Awesome! So she was really lean! Good on 'ya for finding the problem.

    Pump up your tires to 40PSI, and you'll pick up another couple of mph. Also, don't forget to shave before you go out for your test run..(every ounce count 'ya know) :thumb
    #26
  7. creeper

    creeper Still alive...

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    Did I mention I wasn't going to say a thing?... :nod
    #27
  8. Maxmoto

    Maxmoto Anarchist Adventurer

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    Hi there Flanny'
    I had my bike rejetted with exact spects you send it to me while ago. Results was great however I .sold the bike to "Boulder Boy" from Boulder and he wonders what do you suggest for 5500 feet high altitude?
    Thanks in advance
    Moto
    #28
  9. d0gWateR

    d0gWateR Goat Stuntaz DSMC

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    Yours is an '02 right? What kind of grips did you use? I have an '03, so what's the conversion, colour change etc...? Maybe creeper can chime in with some help...

    [​IMG]
    #29
  10. Flanny

    Flanny Flanny-it-up!

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    Well...It's a whole new ball game. I've never jetted for that kind of altitude, but I would suggest that stock air pilot (1.2) and jetting back down to 152 or 155 MJ would be more in the range.

    He'd have to experiment on the main jet in particular and get back to us with the result...I've heard rules of thumb like one MJ size down for every 2000ft of altiture, but I've never tried them in practice.

    Any other people that are high can chime in anytime (litterally or figuratively). :lol3
    #30
  11. ChrisC

    ChrisC Amal sex?

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    My '03 Adventure lives at 6,000 feet. I have the KTM airbox "racing" side cover and the 'Trapp IDS2 installed. I'm still running the OEM jetting (152.5 main/1.2 pilot air) and figure I'm still plenty fat. It runs pretty much perfectly from 6K to 12K, can't beat that...

    CC

    BST!
    #31
  12. Rad

    Rad Done riding

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    I was run'n very lean, guess what...Yup :nod Das boot
    #32
  13. meat popsicle

    meat popsicle Ignostic

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    I was runnin' very rich, guess what... :lol3 der main jet come unskrewed

    do we need a hall of shame?!? somewhere to collect all the bonehead things we did so that people can scan through it to find problemas?

    Are we man-enough to fess up to our little "indescretions"? :D
    #33
  14. ChrisC

    ChrisC Amal sex?

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    How 'bout a "Hall of Meat" to start... :lol3

    So if your MJ was say, a 160 and then it falls out, how to we rate the metering orifice then? Maybe a 860? :eek1


    CC


    BST!
    #34
  15. meat popsicle

    meat popsicle Ignostic

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    I am comfortable with the name "Hall of Meat", but it might get thrown into JM without a glance :lol3

    :dunno what the equivalent size is for no main jet but 860 probably ain't too bad a guess :nod

    I thought the Hall o Shame might be fun to read, maybe useful to a few wrenchin' retards (myself included), and definately a good exercise for those who's ID made it past the Super Ego. Or was the Ego the gatekeeper? Aw, crap I can't remember.

    It might liven up Chopperman's life as the "Blood, sweat, and gears" forum is a little dry. :evil

    I think I'll start it just for giggles - we'll see what happens...

    Link:
    http://www.advrider.com/forums/showthread.php?t=64136

    Don't be shy now ya'hear
    #35
  16. Padowan

    Padowan Adventurer

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    Resurrecting this thread as it seems like the closest to to a problem I have.

    I have recently bought a lovely 2004 640 Adventure-R and have a bit of a problem with it. It seems to be lacking in power at the top end. In top gear, it won't accelerate above 70mph or so (around 5.5k rpm), with WOT, the bike just stops accelerating and I would say that the last 25% of the throttle rotation is doing nothing at these speeds, I can roll back about 25% and nothing changes, dropping down a cog of two allows the revs to increase, but I still hit the same limit (in 3rd the revs will go towards the redline, around 8k or so at 70mph, but when I then change up a gear, the revs obviously drop, but I get no more power/acceleration.

    Bike has Full Akra exhaust, vented side panel on the airbox and no snorkel. It's running a 157.5 main and 47.5 pilot, which I read is about right for those mods.

    I have looked at the following things:
    • Octane switch is properly earthed
    • Had the carb off, set the float level, cleaned all passageways.
    • There is no limiter top-hat in the top of the carb.
    • Slide and guide are showing some signs of wear, as is the needle.
    • Needle is on the middle (3rd) clip.
    • Slide holes are not drilled out from what I can tell.

    I ran an AFR meter on the bike, and at idle it's running around 13.5, on cruise it seems a bit rich at around 11-12. At WOT when the problem is occurring it's at around 13.5, so there's no smoking gun with regards to jetting being wildly out.

    My current thoughts:
    • I'm going to check the compression and get inside the head shortly to check the clearances/rockers and ensure that the cam isn't a tooth out.
    • If the slide/guide is worn and the slide is sticking under the intake vacuum that might give the symptoms I see. When the carb is out of the bike, pulling vaccuum on the top of the carb makes it slide up and down through it's full range, so maybe the issue is when there is lateral intake vacuum pulling the slide into the guide.

    Otherwise the engine starts well and easily and doesn't sound all tappy, and at slower speeds the bike all feels good and seems to have power.

    I'm reluctant to simply start replacing carb components (slide/guide/needle) unless I run out of options, as it'l be easy to spend a couple of hundred notes on parts which may not fix the problem, so want to eliminate everything else first.

    Looking for any suggestions for things to check, or other possible causes of this kind of problem.


    Thanks!
    #36
  17. NitroAcres

    NitroAcres MotoBiggots Suck Supporter

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    Find an FCR39/41 and give it a whirl....
    #37
  18. gunnerbuck

    gunnerbuck Island Hopper

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    Make sure the little metal shim washer is in place on the needle, it is the last thing to go over the pointy end before it is slid into place on the slide..
    #38
  19. timeOday

    timeOday Long timer

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    No doubt you have also cleaned, but not over-oiled, the air filter...
    #39
  20. Padowan

    Padowan Adventurer

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    Appears to be a CV slide issue. It's not moving through its full movement (see vid hopefully, if I can attach it).

    How the slide is responding exactly reflects how the bike feels, like the throttle is only opening part way. //cloud.tapatalk.com/s/5ab2bcbdaac01/20180321_193805_002_001.mp4

    Sent from my SM-A520F using Tapatalk
    #40