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took the carbs to church and now I cant get the bike to start

Discussion in 'XJ Technical Chat' started by NikoRx, Mar 1, 2020.

  1. NikoRx

    NikoRx Member

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    Hello, I have an xj 550 maxim 82', did a carb rebuild, bench sync, measured and fixed valve clearances, even fixed the gas tank which was rusted and leaking. I turned the mixture screws 2 3/4 turns out. it turns over when I press the starter but it doesn't start up even with starter fluid. choke was pulled out as well. there was gas in each bowl as well although I have not done a fuel level check on it. It was running at one point and then I found it had a vacuum leak so I think the fuel levels are fine. I will check that at some point but I want to at least get the bike running to some degree and tune it. I am at a frustrated loss. any advice is welcomed
     
  2. XJ550H

    XJ550H Well-Known Member Premium Member

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    start by ohming out the ignition system
    are your plugs fouled that will happen with starter fluid.
    measure battery voltage before starting and during starting if voltage goes below 10 volts your when cranking bike will not start.
    looking for 12.8 volts before turning on bike.

    keep battery fully charged.
    hit thee prime selection with petcock to make sure bowls are full 5 seconds will do it.


    specs for ignition system and charging system will be found here
    The Ultimate Relay, Switch, Sensor, and Diodes Guide

    remove headlight fuse to keep headlight from coming on.

    clean tci connectors and ignition coil connections use electronic contact cleaner spray and dielectric grease. battery connections dirty connections cause voltage drop.

    check voltage at battery. then fuse in and out then at tci for the ignition system. you are looking for voltage drop as you go deeper into wiring.

    clean ignition switch contacts. voltage flows from battery to main fuse to ignition switch then back to your other 3 fuses

    Clean and lube the ignition switch

    you will need to check wet fuel levels
    Setting the fuel levels

     
  3. Timbox

    Timbox Well-Known Member

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    Yep been there done that. Pull the plugs, are the wet? Place the plugs in the boots and check for spark on each of them. If the plugs were wet, shine the light down the plug hole and see what you have going on in there, wet, full of carbon? If you have compressed air blow out each cylinder as well to dry it out well. If it was not wet and you have everything hooked up, gas carbs ect, they should be wet of have gas in the cylinder.

    Just tapping on the side of the carbs might free up a stuck float bowl as well. Be ready to turn off the gas if you didn't do a fuel level test outside the bike.

    Let us know what you are doing to fix the issue and good luck.
     
  4. NikoRx

    NikoRx Member

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    Hey guys, Quick update. I replaced the fuse box and am quite pleased with the craftsmanship! and it freaking works. I am having an issue with the left turn signal not blinking or blinking once or twice. any thoughts? then the real head scratcher. I'm trying to set the float heights and they were all in spec. when I am measuring the fuel level though they are 10mm from where it is supposed to be which is the section where the bowel and carb body meet. I am fiddling with the tang to increase the fuel level but wont that take it out of spec for the float height?
     
  5. a100man

    a100man Well-Known Member

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    Fuel level in-situ over-rules float height with carbs upside down off the bike.
     
  6. NikoRx

    NikoRx Member

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    thanks man, I am hoping that is the case. its just weird that at one point the bike was running, granted with some issues (vacuum leak in the carbs, shim clearances, etc.) and now the fuel height is low and probably the reason why the bike wont start and the sparks were dry. I feel like I am playing whack-a-mole with these problems
     
  7. XJ550H

    XJ550H Well-Known Member Premium Member

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    If you put a new float needles they are a different length than the originals which is why the float Spec is not as accurate as the wet set
     
    Last edited: Mar 26, 2020
    Timbox likes this.
  8. Timbox

    Timbox Well-Known Member

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    Yes the carbs take some time but it is well worth it. If you don't take the time then you will be taking them back off anyway, so get it done right the first time. As for the turn signal issue how is that battery of yours? New or newer and fully charged? You didn't put any LED's in anyplace? You have changed out the old fuse box but have you cleaned up all the contacts for the rest of the connectors? Weak battery and possibly a bad turn signal relay.
     
  9. NikoRx

    NikoRx Member

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    new and has been on a trickle charge. no LEDs. Probably the connectors or relay switch since I haven't checked them. The fuel Levels were crazy low and I bent the tangs and got them to a more appropriate level but my two outside bowls are nearly in range and my two middle bowls are absurdly low!! any idea what can be causing that? I will be taking pics this weekend of what I am talking about. just very frustrated, I feel like my floats are nearly as high as they can go to let in max amount of fuel. I am about to just take them out to see if the bowls will overflow. I did put in new needles but thought they were the same height as the old ones but will double check.
     
  10. hogfiddles

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

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    What height did you set the floats at?
     
  11. NikoRx

    NikoRx Member

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    15cm
     
  12. NikoRx

    NikoRx Member

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    Whoops I mean mm
     
  13. hogfiddles

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

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    I believe for the xj550, you should make your initial setting at 21.5 mm. The 550 rack is really finicky, so you’ll surely need to do a wet setting.

    the 550 came with a heat shield underneath..... but most times we will not re-install them because in order to adjust float levels, it has to be removed. In order to remove it, the rail screws must come off. When those are removed, the rack becomes a bit “loose”. This will mess up your sync! So just leave it off.

    that said, the mixture screws for the 550 could easily end up even around 5 turn out.....

    As I said before, the 550’s are quite temperamental, and often take more time to dial in.

    dfox
     
  14. NikoRx

    NikoRx Member

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    Thanks for that! I did put the heat shield back on but will leave it off going forward. They were initially at 21.5 mm but the wet levels were very low
     
  15. NikoRx

    NikoRx Member

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    Should I be checking the fuel levels while the bike is on the center stand or should they be off the bike and perfectly balanced?
     
  16. hogfiddles

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

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    Many people check levels with the bike on the center stand, others build a PVC rack to hold the carbs on the bench.

    there are numerous pics of carb stands through the forums.
     
  17. NikoRx

    NikoRx Member

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    Alright, Latest update: I have the carb wet levels finished or at least as close as I could get them! the bike did start!!! but only with the choke on and it went up to 6k and definitely smelt some burning plastic. I cant get it to run without the choke on or to get down to its ideal idle. any thoughts on what I can do next? i assume I have to do something with the Idle screw?
     
  18. hogfiddles

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

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    Keep it running, and play with the idle screw til you can hold an idle that’s not too fast—then try to SLOWLY turn off the enricher. You may have to play with the idle screw , you may have to play with the throttle. Somewhere around 1100-1150. You need to get it to idle on its own, so you can get ready to do a running sync. The running sync, and the color tuning will dial it in a lot more. The bench sync is just to put the rack in a state where the bike can start up and run to warm up so you can prepare for your running sync.
     
  19. NikoRx

    NikoRx Member

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    any advice on a good way to turn the idle screw? my hand wont fit
     
  20. NikoRx

    NikoRx Member

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    never mind I tried it from the other side and I could reach it. My other thought is once I get it to an ideal idle, I shouldn't have any trouble getting it to start when I push the ignition. For humors sake though, if it is still having difficulty firing or takes a while to start what would you suggest I look into as far as possible culprits?
     

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