BST Needle Help

Discussion in 'Thumpers' started by fire_strom, Oct 5, 2006.

  1. meat popsicle

    meat popsicle Ignostic

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    He's around again and fixed some other pic links. PM him if he doesn't show up in a bit. If that don't work, check KTMTalk; much of his stuff is over there too.
    #41
  2. mdogruc

    mdogruc Mesut DOGRUC-Adana/TURKEY

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    One more needle from an all stock 2004 LC4 640 Adv at 32.000kms

    [​IMG]
    #42
  3. tallbob

    tallbob Been here awhile

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    Yeah, me too. I believe it's normal wear. When I got my 99 640E it had 13,000 miles. I checked the carb and raised the needle one slot at the clip and noticed no wear. Now at 22,000 miles mine looks like these pictures. Thanks for reminding me I need to order a new one, unless I get around to installing the FCR. This wear doesn't seem to affect the way the bike runs.:evil
    #43
  4. boyscout

    boyscout sittin' down

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    Just wait till you get in an offroad situation where you need to run for periods at near full throttle. The needle will vibrate to the point that the engine floods. Not great when the engine floods and dies in the middle of that steep scrabbly section that you really needed to clean.
    #44
  5. Jan from Finland

    Jan from Finland Been here awhile

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    Argh! Now I got just 25000 km out of it. Check that needle before you wander far away! I was at Arctic Circle.[​IMG]
    #45
  6. boyscout

    boyscout sittin' down

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    Replace the slide. It will only wear out faster and faster as the hole gets ovalized more and the slide tracks wear down causing added vibration.
    #46
  7. Jan from Finland

    Jan from Finland Been here awhile

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    Is that the reason? I noticed that the hole is oval. Should it be round? Could I remedy it just by gluing the needle to the slide?
    #47
  8. boyscout

    boyscout sittin' down

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    There are two ways it wears out. One is that the hole ovalizes and the other is that the slide tracks themselves wear down and it vibrates in the carb. You can replace the insert that the slide rides in but in my experience all that was necessary was replacing the slide and needle. I doubt gluing the needle would work as it seems to me it needs to move a bit in response to slide movement.
    #48
  9. meat popsicle

    meat popsicle Ignostic

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    I just rebuilt my BST, and after 17,000mi that were not in any race (but 60/40 street/dirt) I can say my slide & guide were worn (never mind the needle jet itself). When I got my rebuild kit and other BST parts from Derek at motolab I thought he might have given me a wrong part... my old slide and guide came apart without any effort, but the new parts were not easy to fit together. I believe that wear would cause leakage past the needle jet.

    If your carb has not been abused and taken care of I would still consider checking these parts every 10K and probably replacing at least every 15K miles. Derek's motolab site has pictures to help you visualize wear patterns, but if you have the slide and guide out it will be pretty obvious.
    #49
  10. Foot dragger

    Foot dragger singletracker

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    Well Hell,Ive got 22,000 miles on my DR,it runs great but maybe my needle is committing suicide un beknownst to me. Ive pretty much made a habit of not working on the DR other then basic maintenance. It had a nasty bog at low revs but cleaning the tiny filter in the carb inlet has it running like new again.
    I guess I will have to actually look inside the carb,no bikes Ive ever had in 40 years of riding have worn a needle anything like the needles in these pictures.
    #50
  11. meat popsicle

    meat popsicle Ignostic

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    my needle jet wasn't worn either (to my eye) but the slide and slide guide were obvious once you had them out of the carb.
    #51
  12. Jan from Finland

    Jan from Finland Been here awhile

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    The needle.

    [​IMG]

    Sorry, no picture of the slide. The hole was oval. The longer axis about twice the diameter.
    #52
  13. clintnz

    clintnz Trans-Global Chook Chaser

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    DR650's don't seem to wear out the BST40 as quickly as the 640, less vibes maybe? But they do still wear them out. Once you have the carb out of the bike it is very simple & easy to strip, clean & inspect, see Laramie's guide on here. It's probably a good idea to give any carb that sees dirt use a clean & check every now & then anyway.

    Cheers
    Clint
    #53
  14. motolab

    motolab Long timer

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    I'm holding a DR slide in my hand, and it has one slide lift hole against the KTM's two. That at least partially explains the difference in wear, as the less slide lift hole area, the more damping and therefore the less flutter.

    Regards,

    Derek
    #54
  15. ER70S-2

    ER70S-2 Long timer

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    I took my DR carb apart to check for this last night. No wear marks on the needle at all. I've never been in the carb before; 18,000 miles. Reassembled with allen head screws.

    I was real happy that there was no silt above the slide from the tiny underseat filter. But I usually ride alone, so I'm not sucking someone's dust.
    #55
  16. motolab

    motolab Long timer

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    Did you inspect the slide guide, slide & emulsion tube?

    See:
    Slide guide, used
    Slide guide, new
    Slides, new and used
    Emulsion tubes, new and used

    Scroll down for description and links. Click image for high-res view.

    Regards,

    Derek
    #56
  17. ER70S-2

    ER70S-2 Long timer

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    Motolab:
    I didn't know about other wear surfaces to check while I was in there. Those are good pics and links are always helpful. The pics were taken very close to my 18k (20k for those that didn't look). As usual, a pic is worth a 1000 words.

    I did check the emulsion tube, (needle jet to me).

    How is the slide guide secured in the carb? Is it available separately? BikeBandit shows the slide to be $51, but not the quide. I had to push firmly on the emulsion tube to get it out of the carb and the slide guide did not try to raise with the emulsion tube. I didn't remove the carb, the two hoses on the right side were too tight and I wasn't up for trying to reconnect them. My point is: I didn't have the carb off, so I couldn't see the obvious.

    Thanks again for the links.
    #57
  18. trailrider383

    trailrider383 867-5309

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    I checked my DR650 carb at 21,000 miles. 19,000 of those miles were with the DJ needle. No wear at all. I had bought a new needle jet to compare with the old one. I took drill bits out of a numbered drill index until I found the size that fit the ID of the needle jet. No discernible difference from new to old. I installed the new one anyway.
    #58
  19. motolab

    motolab Long timer

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    The emulsion tube holds the slide guide in place, so once the emulsion tube is removed, the slide guide should pop right out. I have the slide guides and the o-rings which seal the slide guide to the carb body in stock (see http://www.advrider.com/forums/showthread.php?t=528038).

    Regards,

    Derek
    #59
  20. motolab

    motolab Long timer

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    A word of caution: At low slide heights, as little as .0005" of emulsion tube wear will cause a measurable difference in mixture strength. Detecting .0005" of wear via the insertion of the closest drill could be difficult.

    Did you inspect the slide guide for wear?

    Regards,

    Derek
    #60