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Xj750 CARBURETORS

Discussion in 'XJ Technical Chat' started by Codysc843, Mar 24, 2020.

  1. Codysc843

    Codysc843 Member

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    Ok thanks, are there any other things inside the carburetor that absolutely have to be cleaned in order to make the bike run?
     
  2. Codysc843

    Codysc843 Member

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  3. Simmy

    Simmy Well-Known Member

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    Why do you continue to ask the same thing over and over?
    Everything is discussed in the "church of clean", read this and you will be an expert.
    The carb bodies need to be isolated from everything else.
    The carb bodies need to be clean, all passages clear.
     
  4. Codysc843

    Codysc843 Member

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    Same question never got answered seeing as the jets were clean and floats etc I was asking if anything else needed cleaning to make the bike run. Why u got an attitude?.. anyways.
    I've heard people mention little filter screens inside the carb itself and other things I don't see any small screens or anything else that needs cleaning just wanna be sure before I get it all put back together and get aggravated putting the carbs back in
     
  5. Codysc843

    Codysc843 Member

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    Ok so I'm rolling with the carbs as is but I noticed there's 3 threaded holes and since I've owned this bike no jets were in the bottom 3rd hole but it is threaded am I missing a jet or?
    (Picture below)
     

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  6. jayrodoh

    jayrodoh YimYam Premium Member

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    Some hitachi carbs had a cover over the air jets, later ones did not. That was the mounting screw hole. You’re good to leave it unoccupied.
     
  7. Codysc843

    Codysc843 Member

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    Alright by the way if anybody needs an easier way to mount the carbs lol redneck ingenuity check out the pictures easiest I've ever got the carbs on..

    Update the bike (with a temp gas tank a 20oz coke bottle) will still not crank I've let all the jets soak over night and sprayed them again. Bike sounds like it's about to crank like it wants to crank a steady rumble but no VRAM VRAM sounds even more like it wants to crank when I took the now empty temp tank and squeezed it and it sucked back to normal shape it really sounded as if it was going to crank then yall keep in mind without the carbs on it at all it did fire up with gas soaked rags in the intake but now I've cleaned them pretty thoroughly and I've cycled the choke and still nothing
     

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    Last edited: Mar 29, 2020
  8. hogfiddles

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

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    Did you;

    1. disassemble the rack to the condition that I showed you?
    2. Did you spray carb cleaner through every single passage so that it would spray out somewhere else?
    3. Did you do that with EVERY hole?
    4. Did you use compressed air EVERY hole to verify that every passage is clear?
    5. Did you verify that every jet is clear?
    6. Did you replace the throttle shaft seals?
    7. Did you replace the fuel rail o-rings?
    8. Did you bench-sync the rack?
    9. Did you do anything with the mixture screws?
    10. Did you do anything with you float heights and fuel valve needles?
    If the answer is NO to any of those, that’s a big clue....
    11. Have you capped the #3 vacuum port yet? In the pic it is still open
    12. Your cable going to the throttle is not seated in the cup.
    13. Are you sure you have the cables going to the correct spots?

    btw, easiest thing to pop the rack into the boots—- use a hot air gun, warm the boots, and use a light coating of oil or Vaseline. They pop right in by hand.
     
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  9. Codysc843

    Codysc843 Member

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    Bike runs changed plugs fired up good can the bike run around the block without the airbox?
     
  10. hogfiddles

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

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    probably but it won’t breathe right
     
  11. Codysc843

    Codysc843 Member

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    Ok and correct me if I'm wrong but the regulator would be left side near the tci box correct?
    If yes than will it stay running without one cause there's a loose adapter nothing plugged in and idk if the stator charges it or I have to have a regulator or does something else plug in there?
     
  12. SQLGuy

    SQLGuy Well-Known Member

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    Yes, the regulator is the heat sink finned box next to the the TCI. IIRC, it has a cable coming off of it, with an 8 position, 7 pin, plug a few inches down the cable. As long as there is a battery, the bike should be able to run, for a while, without the regulator connected.

    These bikes use alternators with field windings, so the regulator adjusts the field strength to regulate the output voltage, and also includes the rectifier module.
     
  13. hogfiddles

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

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    Without a regulator, keep the rpms down or you’ll start blowing lights and fuses.
     
  14. SQLGuy

    SQLGuy Well-Known Member

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    Um, no. Not in these bikes. The regulator/rectifier is one unit. If you disconnect it, you will have no output at all from the alternator feeding into the electrical system.
     
  15. hogfiddles

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

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    Well, that’s not how i recall it working on my xj’s ive had enough with bad ones. I’ve blown enough bulbs and fuses because of bad ones.... as the rpms go up, things started to blow especially above 15.5-16 volts.....I don’t think I said to disconnect it though....
     
  16. SQLGuy

    SQLGuy Well-Known Member

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    You said "without", and he said he thought it was disconnected.

    A bad regulator, that was feeding full power to the field winding... yes, that would cause overvoltage and blow things.
     
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  17. hogfiddles

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

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    Fair enough—- I should have said it clearer
     
  18. Codysc843

    Codysc843 Member

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    Well yall I've rode it around the block twice it runs good I need to tune the idle it revs way to much at a quarter turn of the throttle also when I parked it both on the 1st and 2nd time good bit of smoke was still coming out the exhaust what's up with that?

    As for the regulator there's not one I see connected but it did ride good didn't shut off on me
     
  19. SQLGuy

    SQLGuy Well-Known Member

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    Please post photos of what you're seeing, or not seeing, with the regulator. With no regulator, it will run for a while, until the battery is too low to continue powering the ignition.
     
  20. Codysc843

    Codysc843 Member

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    I know there's no regulator cause the plugin is hanging behind the tci box
    Think the smoking exhaust stopped after I road it again next step is to fix the tuning on the carbs cause at quarter turn it revs like your drag racing I think the butterfly valves may be open too much
     

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