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XJ650 Start up rev issue

Discussion in 'XJ Technical Chat' started by Daniel Diblasi, Feb 16, 2018.

  1. Daniel Diblasi

    Daniel Diblasi New Member

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    I recently put together my xj650 and I started it for the first time today and as soon as i start the bike it revs up to 7k and I have to kill it. I put new spark plugs, new oil, fresh gas, new fuel line and filter, Cleaned carbs, Air filter pods and fresh charged battery. I really dont know what is wrong, cant keep it running at that high rpm to try and adjust things on the fly. Anyone have a fix to this problem?
     
  2. k-moe

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

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    You likely have a vacuum leak.
    How did you clean the carbs?
    Did you rejet for the pods?
    Do you still have the airbox?
    Did you check for cracks in the intake boots and vacuum plugs?
     
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  3. MattiThundrrr

    MattiThundrrr Not a guru

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    To achieve further clarity, did the throttle shaft seals get replaced during your carb clean?
     
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  4. Daniel Diblasi

    Daniel Diblasi New Member

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    I checked, but all the boots are new.
    For the carbs I took both ends off sprayed carb clean all through and put new gaskets on the fuel bowls. I didnt know if the top ones needed gaskets cause there wernt any on there.
    I did not rejet becuase i modified the pods as seen in this video().
    I have the air box but it is bad shape and the guy I bought it from didnt have the airbox boots.
     
  5. XJ550H

    XJ550H Well-Known Member Premium Member

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    have you checked the idle adjustment knob it may be turned in to far.
    how about the throttle cable should be out of adjustment a small amount of slack at carbs . is the linkage at carbs moving freely. and bottoming when throttle is released?
    remove the pods see if you still have the same problem could be you overdid the videos suggestions.

    do the slides move up and down freely with a clunk when released?
     
  6. XJ550H

    XJ550H Well-Known Member Premium Member

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    does your bike stall out at high rpm or do you shut it down?

    added
    throttle connected to throttle linkage and choke cable hooked to enrichment circuit not reversed?

    and are you shutting off choke when bike starts?
     
    Last edited: Feb 17, 2018
  7. Daniel Diblasi

    Daniel Diblasi New Member

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    It seems that the idle adj is not working in either direction.
    Yes the linkage is free but I dont know if its bottoming because it is idling at about 5k.
    It started idling at about 1-2 for a little but realized the fuel was shut off.
    The bike just sits at 5k and we try to adjust the idle and throttle but nothing happens and we kill it.
     
  8. Daniel Diblasi

    Daniel Diblasi New Member

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    No, honestly have no idea what that is.
     
  9. XJ550H

    XJ550H Well-Known Member Premium Member

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    disconnect the throttle cable from carbs , first try pushing down the enrichment plungers
     
  10. XJ550H

    XJ550H Well-Known Member Premium Member

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    there are 2 seals on each carb that seal the throttle shafts if they leak rpms will climb
     
  11. k-moe

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

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    Last edited: Feb 17, 2018
  12. Jetfixer

    Jetfixer Well-Known Member

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    You need to take carbs to the church of clean or you can have a poor running bike it is your choice we are trying to help you solve the problem your having. Your carbs need a full tear down and soak in carb cleaner...spray carb cleaner will not get into small passages inside carb. If you break the rack and seperate the carb bodies and remove the butter fly plate and the shaft , this is where you will find the butterfly shaft seals there is an inboard and outboard seal . Replacements can be purchased from xj4ever ....you will NOT get these with most rebuild kits. If I recall as an alternative 2#11 buna O rings can be used also. If you soak a carb body without removing shaft seals you are going to cause the seals to perish and never reuse the old seals. Good luck.
     
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  13. Daniel Diblasi

    Daniel Diblasi New Member

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    I had the bike running and the throttle was reving when twisted a few weeks ago but i recently finished all the wiring and now when I start it, the bike will idle fine and it revs up with the choke but as soon as I twist the throttle the bike dies. At first I thought it was just out of gas but I filled the tank about halfway and it did the same thing. I tried taking the inline fuel filter out and running it directly into the carbs but it didnt seem to do anything. Any suggestions?
     
  14. XJ550H

    XJ550H Well-Known Member Premium Member

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    did you have the carbs out or cables off recently? if so make sure you put the cables back on correctly. choke cable has a clamp holding it on the right side of carbs between carbs 3 and 4. Throttle cable goes into cup bracket nearer the middle of carb banks between carbs 2 and 3


    OWWW, My Eyes!
     
  15. Jetfixer

    Jetfixer Well-Known Member

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    As Dr Evil said Need the Info people....are you running stock airbox or pods? Have you rebuilt your carbs fully ( church of clean) ? Have you done a running synch? What condition are your boots in? Have you checked for vacuum leaks? Have you adjusted valve clearance? Are your mixture screws set at 2.5 turns? What is your idle rpm set to?( 1100 is where mine is happy)what about jetting stock or pods and bigger jets? All items can cause issues Inquiring minds want to know.
     
  16. XJ550H

    XJ550H Well-Known Member Premium Member

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    lets try the simple stuff first
     
  17. Daniel Diblasi

    Daniel Diblasi New Member

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    Yes I checked the cables and they are all in the correct position.
     
  18. Daniel Diblasi

    Daniel Diblasi New Member

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    I am running pods that I modified to adjust to the amount of air coming through so i wouldnt have to rejet(seen in the picture). I had my buddy who is a motorcycle mechanic adjust the carb butterflies and it ran without a problem. I did not know about the mixture screws i can check that. My idle is set around 1100 and it was idling fine. My boots are all new. I have a feeling there is a problem where its not getting enough fuel. I tried taking out the inline fuel filter and just running a direct fuel line but that didnt seem to do anything. but i did notice that fuel wasnt getting pulled through the line and i would siphon it through and it woulf stay running. Also is the secondary line coming from the fuel tank that goes right into the carb boots, is that a vacuum line? Like I said it was running great and it was reving when i twisted the throttle just a few weeks ago and I didnt change anything and this problem is now happening.
     

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  19. XJ550H

    XJ550H Well-Known Member Premium Member

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    ok thanks for the history as well.
    is your tank full or at least have 2 gallons of fuel in it? you have a 3.4 gallon tank with .8 gallon reserve
    the second line is a vacuum line is it connected? it connects to the nipple on manifold boots. if it is not connected fuel will not flow.
    test you petcock. fuel is gravity feed and not sucked into carbs.

    turn petcock to prime and run fuel hose into a mason jar see if it flows well. or just see if the bike runs well on prime
    then turn to on or reserve.
    do you have a vacuum pump/bleeder if so apply vacuum to petcock vacuum port see if fuel flows from petcock in the on and reserve position

    if you do not have a pump just attach a hose to vac port and suck on it fuel should flow

    if i understand you correctly you are siphoning from tank to carbs. if this is the case I would look at the petcock and vacuum line there is also a vent in gascap that should be cleaned out but if this is happening on start up cap should not be the problem but clean it any ways. unlock it to break the seal
    you could have a bad vacuum line replace it. size is 4mm id
    Your Gas Cap and You
    . if you have non vacuum petcock plug the vacuum line a cap on the nipple on manifold boot would be best.


    you will need to rebuild or replace your petcock if it fails the above tests

    will the bike run with out the pods and respond to throttle? could be you over modified them.

    your bike is an XJ650 correct?
     
    Last edited: Apr 18, 2018
  20. XJ550H

    XJ550H Well-Known Member Premium Member

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    in your other post you say "It started idling at about 1-2 for a little but realized the fuel was shut off." , do you have a manual petcock?



    XJ650 Start up rev issue

    moderators would you merge these threads for clarity?
     

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