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Ninja EX500 carbs on an XS650?

Discussion in 'The Garage' started by Highside, Oct 20, 2011.

  1. peanut

    peanut XS650 enthusiast & inveterate tinkerer XS650.com Supporter Top Contributor

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    yes I wasn't really aware of this before buying them but I'm sure there will be a way of modifying the throttles to accept an external adjust screw I'll take a look at them when I get back off holiday.
    The sync screw will work fine with the screw pointing either way.
     
  2. 650Skull

    650Skull Dinosaur Lives Top Contributor

    ...........
     

    Attached Files:

    Last edited: Jul 17, 2019
  3. aldo5468

    aldo5468 Redleg XS650.com Supporter

    Thanx for your suggestion. The first thing I tried was my trusty 55-year old offset screwdriver; it had maybe 15 degrees of "swing", not enough to even engage the screw, let alone turn it a bit. Never had BS38's but ran 34's for about 6 years before updating to CVK's. I did synch the 34's on the bike but probably had the tank off the times I did it. Agree that any adjustment should be minor after a good bench synch. In my experience and opinion, it's still worth checking and fine trimming if possible - synching any carbs within an RCH on these 650's is the best single thing you can do to minimize vibration, plus it accounts for any other factors beyond the carbs that may affect strength of vacuum on one side or the other.
     
    peanut likes this.
  4. 650Skull

    650Skull Dinosaur Lives Top Contributor

    ex   500.JPG
     
    Last edited: Jul 17, 2019
  5. aldo5468

    aldo5468 Redleg XS650.com Supporter

    Yeah, that's the one referenced in post #880, used on 2000-2001 Kaw W650's per the carb fiche for that bike. The fiche doesn't show any other applications, so likely a pretty rare as a salvage item.
     
  6. aldo5468

    aldo5468 Redleg XS650.com Supporter

    You'll find that you won't need the "push" cable and can safely trim off its tab if you want to "declutter" - return spring on these carb sets is quite strong.
     
  7. highboy_coupe

    highboy_coupe XS650 Addict

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    Right, been out for a few runs with my new 1.5" stainless pipes, and I reckon I might be a tad lean on the mains; I could maintain a steady (albeit buzzy) 90mph with the standard pipes, but now I get to 80mph and it runs out of puff.

    I went with 38/138 and JJJ(middle clip). Here are my plugs, a bit white??
    IMG_20181031_180924.jpg

    IMG_20181031_180516.jpg
    I have some 142 jets ready to go, might be a big jump from 138? I noticed someone else with foam pods/straight through exhaust had 140s.

    Thanks carb gurus
     
    gggGary likes this.
  8. peanut

    peanut XS650 enthusiast & inveterate tinkerer XS650.com Supporter Top Contributor

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    if it was running fine before the exhaust change then it would suggest that your new system is restricting the air flow........ have you checked the difference in wadding and baffles ?
    The usual advice re main jetting is to start too big and work down so chuck the 142 jets in and test them.

    You'll not likely to see much colour on new plugs unless you've put in some miles in
     
    Last edited: Nov 1, 2018
    highboy_coupe and gggGary like this.
  9. Sci85

    Sci85 XS650 Addict

    Those look a little lean but is that from a WOT plug chop run? I have 138 mains, straight through shorty mufflers and foam filters and she runs great at WOT. If your running steady 80/90 mph, are you at WOT? If you're at 1/2 or 3/4 steady throttle, the needle is doing the metering. I also run the JJJ needle and my midrange is good. I don't run at 90mph though. Too much shake lol. I'm with peanut. Sounds like restricted air flow...
     
    peanut, highboy_coupe and gggGary like this.
  10. 650Skull

    650Skull Dinosaur Lives Top Contributor

    better to have a full range of jets...........

    Changing jet sizes one at a time, work your way up till it runs good.......go bigger till it starts to run rough..........then go back down a size till it runs good again.........That's where it wants to be
     
    highboy_coupe, robinc and gggGary like this.
  11. highboy_coupe

    highboy_coupe XS650 Addict

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    Thanks for the responses guys.
    To answer Sci85, yes this was a WOT run, a mile in fact, then shut the bike off without idling and rolled into the garage, the midrange is excellent, nice and punchy.
    At WOT it hit around 80mph then just sat there, not getting any faster, it wasn't breaking up or anything, best way to describe it was when you get a 125cc bike up to 65mph into a headwind, nothing much more happens!

    Peanut - There is no wadding in the pipes, there are some bolt in metal baffles, like drag pipe baffles you can buy off eBay. I can remove them.
    The mufflers themselves are straight through with perforated inners, so I if i did remove the baffles and still have some noise deadening.

    I will stick the 142 jets in, it can't hurt.
    Thanks again
     
  12. gggGary

    gggGary Stop that! XS650.com Supporter Top Contributor

    Removing the baffles should be an easy test of jets? if it runs better you are too rich. worse and you are lean. Aftermarket exhausts are seldom (read never) exhaustively tested, that's a pun:mad: aftermarket with baffles may not flow as good as stock. EMGO LOL
     
    peanut and highboy_coupe like this.
  13. peanut

    peanut XS650 enthusiast & inveterate tinkerer XS650.com Supporter Top Contributor

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    good advice from sci85 who I believe he is the only one of us that has actually fitted and tested the carbs and has them working well .;)

    If the engine is holding back at WOT it should be doing that in every gear not just flat out in 5th

    I'm afraid that I am going to have to disagree with skulls advice about jetting .....When changing and testing your main jets one should start too rich and work down NOT UP .
    Running your engine at WOT with a rich mixture will not damage your engine whereas running with a lean or weak mixture is a sure way to end up with your pistons seizing at high speed or deceleration and eventually holed pistons .
     
    Jim, Sci85 and highboy_coupe like this.
  14. highboy_coupe

    highboy_coupe XS650 Addict

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    I understand what you are saying, and yes it is probably holding back in all gears, but I really only a have a solid memory of what it was doing in 5th before I put these exahusts during some test runs (with the cvk carbs on and everything else the same).
    In the lower gears it might feel a little like when a diesel hits the top of the rev range, a bit breathy, or it might be my imagination? It is certainly making a nicer (louder) noise!
     
  15. 650Skull

    650Skull Dinosaur Lives Top Contributor

    can't read posts when you have people on ignore........Agree disagree............common sense tells me when i screw in a mixing screw and listen to any change i will run it past the running good point till it runs rough then turn it out to the best position............
     
    gggGary likes this.
  16. wannabridin

    wannabridin XS650 Guru

    As I tell anyone that asks or "needs" to hear, consider the value of your time tuning this vs. a dyno-tune session. As long as the rest of the motor is running strong and your intake/exhaust is how you want it, a dyno session runs about $300 and up but it's (typically) and one-and-done event. I took my Shadow in to one and half a day later it ran better than i EVER could have! Instant throttle response, no flat spots and a flatter torque curve!

    I will only take mine to a dyno now a-days, as I feel the improvements are VERY much worth it. Heck, a good shop will even do a single pull for you to baseline you and if you're within an "optimal" range, you can get out without any work for far less!
     
    highboy_coupe likes this.
  17. peanut

    peanut XS650 enthusiast & inveterate tinkerer XS650.com Supporter Top Contributor

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    Its not my opinion its recommended practice to start over-rich and work down to correct jet size on main jets when testing at WOT.

    I'm 'all for' the application of commonsense in the absence of available recommended good practice .
    By the way what has adjusting idle mixture screws got to do with changing Main jets and WOT testing?
     
  18. 5twins

    5twins XS650 Guru Top Contributor

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    He was just illustrating the basic carb tuning technique of going above and below the ideal adjustment or jetting to "bracket" it and determine just exactly what it should be. One of the first rules of jetting is that when you think you're good, go up another size to see if it runs better or worse, just to verify your previous selection was best.

    If a carb set has an established baseline, which this seems to, I don't see the need to start way rich and work down. I'd just pick a size in that baseline, in this case a 138 or 140, and work up one size at a time from there. Any of these baseline sizes are probably close, in the "ball park", so don't skip sizes. Just one size change could make all the difference and totally fix the issue.
     
  19. 650Skull

    650Skull Dinosaur Lives Top Contributor

    I was told, (by you), i was on your ignore list...............keep it that way will you.

    You are trolling.......No need to comment on my comments that aren't directed at you ....or at all
     
    Last edited: Nov 2, 2018
  20. 650Skull

    650Skull Dinosaur Lives Top Contributor

     

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