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no fire on cylinder 1 xj550

Discussion in 'XJ Technical Chat' started by josh naber, Aug 10, 2015.

  1. josh naber

    josh naber New Member

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    So I did a compression test, and the results came in at 125 psi on cylinder 1, 93 psi cylinder 2, 105 psi cylinder 3, 140 psi cylinder 4.
    it seems pretty weird there is a almost 50psi difference between my cylinders, however when I tested I left all plugs in the engine, and never held the throttle open, plug caps were off though. So, would my next step be to do a valve check/adjustment and then redo the pressure test? If so, how do you do a valve adjustment on these engines?

    thanks
     
  2. josh naber

    josh naber New Member

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    im thinking that possibly the difference in cylinder pressure is causing my misfire..
     
  3. k-moe

    k-moe Pie, Bacon, Bourbon. Moderator Premium Member

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  4. XJ550H

    XJ550H Well-Known Member Premium Member

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    you should unplug the tci when doing the compression test also throttle wide open remove air filter
    550 engines:
    Minimum: 100 psi
    Standard: 121 psi
    Maximum: 135 psi
    Max. variance between lowest and highest: 14 psi
    READ how to do the test PROPERLY
    http://www.xjbikes.com/forums/threads/the-information-overload-hour.27544/
    it is very close to the top of the page
    you have to do it right to do it right.
    retest so you have the correct info to compare to when you change your shims.
     
  5. josh naber

    josh naber New Member

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    So my engine is running better now that i adjusted my floats and synced the carbs. However it is still running rich on two cylinders, and im thinking its maybe my emulsion tubes that ate plugged... Now the isue is getting them out with out destroying the carb body. From what i can see the push from the bottom up into the carb body. They are so coroded they just will not come loose even after using a large hammer and a socket that fits the tube right... Any ideas on what to do?
     
  6. XJ550H

    XJ550H Well-Known Member Premium Member

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    do not use a socket use a dowel . the jet holds them in place . you remove the slide
    if you look at the naked carb photos
    http://www.xj4ever.com/inside your carbs.pdf

    page 22 you will see how things flow into the carb you want to squitr carb cleaner into the air jet on the right side of the carb rear of carb the cleaner will flow down to the emulstion tube it should come out the main jet hole. also if you squirt it in where the slide needle it will come out the main jet hole.

    tape or plug the main jet with something and fill up the holes with cleaner and let it soak in then remove main jet and try tapping it out from below

    edited out removed direction someone slap me .
     
    Last edited: Aug 20, 2015
  7. MN-Maxims

    MN-Maxims St. Paul Minnesota

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    XJ550H
    Hold up a sec here, look at page 24 of inside your carbs.pdf. You will clearly see that the brass emulsion tube is machined on the slide (upper) side of it with a shoulder and must be driven up from the bowl side once the jet and copper washer removed. Unless I am missing something here the jet and copper washer hold that emulsion tube in place from the bottom side and would have to be driven out going up.

    You may want to revise your statement "THEY SLIDE OUT INTO THE BOWL SIDE NOT UP"
    Please correct me if I am wrong
     
  8. Rice_Burnarr

    Rice_Burnarr Member

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    Unscrew the main jet from the bottom making sure you get the washer out as well, and then tap the emulsion tube up into the carb throat:

    [​IMG]
     
  9. XJ550H

    XJ550H Well-Known Member Premium Member

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    you are correct
     
  10. josh naber

    josh naber New Member

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    So I guess I never realized that there is a washer sitting on the tube under the jet "smacks head" im lucky I never cracked the carb body heating it up and pounding on it.. How do you get the washer out? can you just pick it out fairly easily?
     
  11. hogfiddles

    hogfiddles XJ-Wizard, Host-Central NY Carb Clinic Moderator Premium Member

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    After the jet is unscrewed, the washer lifts right off. It may be gummed, but a small pick or screwdriver carefully used will lift it.
     
  12. Rice_Burnarr

    Rice_Burnarr Member

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    Haha! Yeah, after you said you had a socket that fit the tube right I was wondering if you knew there was a washer there. I was picturing you pounding on the washer wondering why the emulsion tube wouldn't come out. That's why I specifically mentioned the washer. :)

    Glad you didn't crack anything!
     
  13. MN-Maxims

    MN-Maxims St. Paul Minnesota

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    No worries
    Just didn't know if something was different with Mikuni 550 carbs. I know I had some apart years ago. Thought they were the same as the Hatichi's I'm always messing with.
     
  14. josh naber

    josh naber New Member

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    Well they were pretty much plugged solid through all the little air holes. Now that there cleaned and back in the bike she's a whole new beast :) should it still pull hard past 130 kms in 6th gear. It seems to go like a scared rabbit up to about that speed...
     
  15. Rice_Burnarr

    Rice_Burnarr Member

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    Excellent. Now that you've got the emulsion tubes cleaned out, check your plugs in a little bit to see what they look like.
     
  16. josh naber

    josh naber New Member

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    So my plugs look great, and the bike runs good with plenty of power, the only thing is it seems to have very poor top end power, the fastest i can get it to go is 132 kms/ 82 miles per hour.. And by the sounds of it this bike should do at least 100 mph. Because im running straight exhaust with no bafffles could this effect the top end power. Up to that speed it pulls really hard. Any help would be appriciated
     
  17. k-moe

    k-moe Pie, Bacon, Bourbon. Moderator Premium Member

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    Yes.
     
  18. chacal

    chacal Moderator Moderator Supporting Vendor Premium Member

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    Rice_Burnarr........nice picture!
     
  19. Rice_Burnarr

    Rice_Burnarr Member

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    I don't ride fast so I'm not the best source to provide input into your high(er) speed question, but I did recently approach the speed you mentioned and at that point my bike felt like it had plenty more where that came from.

    So I'm no expert on high speed operation, but in addition to the potential tuning issues caused by the pods and straight exhaust, I would consider fuel sources to rule out high load fuel starvation issues. Float bowl levels, dirty float valve beanie filter screens, dirty and potentially clogged petcock, carb bowl gaskets, and maybe even a partially clogged gas cap vent. That kind of stuff can go unnoticed because it doesn't have impact under low load, low fuel consumption conditions. But under high speed, high fuel consumption conditions, you may be (temporarily) running out of fuel.

    You might be able to test for tuning issues by adding a little choke when you've topped out. If your bowls are full, you should be able to introduce additional fuel to the mix by giving it some choke. If choke helps at high load, you're probably looking at a tuning issue. However, if choke doesn't help, it might be because your bowls have been sucked dry due to the load and there's no additional fuel to add even with the choke. Although it might depend on how low the level is... The choke pickup might be lower than the main jet.
     
  20. Rice_Burnarr

    Rice_Burnarr Member

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    Haha! Thanks! Couldn't have done it without you. ;)
     

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