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Carb Adjustment

Discussion in 'The Garage' started by hardtailed77, Nov 27, 2010.

  1. Firstly let me say that I'm SO happy to finally see a forum for our bikes (or at least one that I dont have to translate!). I'm in southern Indiana, and have been riding for about 3 years. I built mini-trucks before getting into to motorcycles. I will do my best to help anyone I can, and appreciate any help I get.

    I have a pretty easy question...Does anyone know the carb screw settings from the factory for a 1977 XS400D (idle set screws, etc.)? I have a manual, but I left it at a buddy's shop. Thanks ahead of time for all of the help from you guys. I think I'm gonna like it here!:thumbsup:
    Kat Majdali likes this.
  2. CadXS

    CadXS XS400 Addict

    From my Haynes manual...


    Hope this helps:)
  3. Awesome! Thanks alot, that is exactly what I needed. I just needed a factory setting to start at, so I can tune from there since I have wide-open pipes and pod filters. The bike runs decent at the moment, but the left cylinder has way more pressure at the end of the exhaust tip than the right side does, until you get into the throttle at all. After that, it seems to be totally fine. So I'm thinking that the right carb is flooding the cylinder until you crack the throttle and the engine burns off all the excess gas. I'm going to tune the carbs and then test out my homemade manometer that I just built, and go from there. Thanks again for the quick reply.
  4. CadXS

    CadXS XS400 Addict

    No problem mate.

    Post up some pictures of your bike so we can see what you are working on...
  5. drewpy

    drewpy Excess twin Top Contributor

    do at least 3 turns, the factory setting is weak for import/environmental legislation
  6. Kbarkilr

    Kbarkilr XS400 Member

    Hey . . . if you get the adjustment figured out, post your results here. I'm going to run the same setup (straight pipes, pods) but I am seriously thinking about using Uni's on it instead because of the hard times others have had trying to get the standard pods to work. Pretty sure we'll both have to re-jet! Anyone out there have a straight-pipe, pod set-up that they have mastered the tuning on?? Wondering what size jets to go with!! Not trying to hi-jack this thread hartailed77, but it seemed to fit here! Good luck with your adjustments!!
  7. Ebola Monkey

    Ebola Monkey XS400 Enthusiast

    I had the same unequal exhaust pressure on both of my XS'. I suggest checking the pilot, and needle jet for blockage. You're most likely nearly running on 1 cylinder at idle. I know both of mine had that problem initially.
  8. CadXS - Thanks again. I am out of town for work until December 8th, but I definitely have plans to post up an album when I get home.

    drewpy - Thanks for the suggestion. I was thinking that 1 and 1/4 turn sounded a little low, so I will keep your advise in mind.

    Kbarkilr - No problem man, you're not hijacking at all. I love the information you can take home from forums like this, and it seems that this one will be stocked full of useful things. I have the bike running pretty good right now, just need to get it dialed in perfectly. I dont really think I'll need to rejet, but I may be wrong. I am running the exact set-up on my KZ440 and didnt have to rejet, even though everyone said I would have to. We'll see I guess. When I get it spot on (if I do!), I will let you know here for sure!

    Ebola Monkey - Thanks man. I have taken both carbs COMPLETELY apart (leaving them in the rack) and cleaned everything very well with carb spray, and compressed air. When they were off the bike, I noticed that the right butterfly on the engine side of the carb was about a 16th of an inch more open than the left one. That's why I think that side is flooding. When I put any throttle to it, the right cylinder kicks in just fine.
  9. Ebola Monkey

    Ebola Monkey XS400 Enthusiast

    Yeah, your carbs are probably pretty unbalanced. Adjust them so they look the same (bench balance) then do a full balance with the bike running.
  10. Thanks for the advice. I actually just finished my homemade carb sync tool the other day, so i plan to test it out when i get home. Hopefully I dont have to rejet.
  11. Ebola Monkey

    Ebola Monkey XS400 Enthusiast

    You'll have to rejet with open pipes and pods.

    I bought 2 sizes up on the pilot, and main from mikes XS. Ended up using 1 up from factory on both, and mine has stock pipes, and pods.

    Jets are so cheap it's easy to order 2 or 3 sizes just in case.
  12. Ok, thanks for the heads up. I know alot of people told me I would have to rejet with open pipes and pods on my KZ, but I actually didnt have to. I think I'm going to order a few sizes anyways, like you said, it cant really hurt much. Plus, I have a few other odds and ends that I wanted to get from Mikes, so I'll just get them now to save on shipping.
  13. mcrowell75

    mcrowell75 XS400 Enthusiast

    I'm definitely interested in this thread. Please keep updating and posting your results.

    I'd love to know what your final settings/jets are when you get it running smooth with straight pipes and pods.
  14. I will definitely post up my final settings, if I get them right. lol It may take a little while because of the work, holidays, having to wait shipping times on the jets, etc. I will post the results here, and can PM you personally also, if you want.

    By the way, welcome to the forum!
  15. xschris

    xschris XS400 Guru Top Contributor

    i know on my xs650 i had to change the needle setting on the slide as well as the pilot jet and main jet.
  16. bcbobbers

    bcbobbers XS400 Addict

    Hey all I am also new to the xs400 forum and was very happy to see the site made. I had been browsing the xs650 site until now.

    Anyways I'll save my intro for a new post, but am also very interested in your final findings on the jet sizes to use with pods and open pipes. I am also planning on doing this on my 81 xs400 and all the information would be greatly appreciated.
  17. I wish I had some useful information for you, bcbobbers.... I have the entire bike torn down to the frame, and haven't really messed with much of it at all. I'm hoping to start the rebuild soon, so I will definitely let you know what I find out.

    Welcome to the Forum!!!
  18. Sokrates

    Sokrates www.xs400.net

  19. mcrowell75

    mcrowell75 XS400 Enthusiast

    I put brand new pod mufflers (no oil) and 2 brand new MAC mufflers on my 78 XS00-E.

    Here are my jetting results.

    1 size up on the pilot (45)
    2 sizes up on the main (137.5)
    I dropped the clip on the needle one notch.
    2 and a half turns out on the air screws.

    I think I am very close, the plugs look good, I have smooth and steady idle, and it revs up and down without hesitation.

    It might be a tad rich at idle but I want to ride for a while to check.
    Its definitely nothing that the air screws wont fix.
  20. mcrowell75

    mcrowell75 XS400 Enthusiast

    Oh yeah,

    I also set my floats at 32mm. I know that seems ridiculously high. But that comes straight from the haynes and yamaha manual.

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