1. Hello Guest. You have limited privileges and you can't "SEARCH" the forums. Please "Log In" or "Sign Up" for additional functionality. Click HERE to proceed.

Need help 85 xj700 carbs

Discussion in 'XJ Technical Chat' started by Spitfrog, Jul 21, 2021.

  1. Dan Gardner

    Dan Gardner Well-Known Member Premium Member

    Messages:
    1,177
    Likes Received:
    568
    Trophy Points:
    113
    Location:
    Minneapolis, MN
    @VanDutch - there are a total of 7 hoses attached to the XJ700N carbs:
    4 vent hoses that come off near the enrichment plunger. Hoses are 8-9 inches long and just hang down behind the carbs.
    2 fuel overflow drain hoses. One is attached to a T between carbs 1 and 2, and one is attached to a T between carbs 3 and 4. They are a little longer and hang down behind the engine under the airbox.
    And of course, the fuel supply hose from the petcock.

    I don't have my 700 out yet for the year, but maybe I can get some more photos soon.
     
    VanDutch likes this.
  2. VanDutch

    VanDutch New Member

    Messages:
    11
    Likes Received:
    0
    Trophy Points:
    1
    Location:
    Austin Texas
    Thank you for your quick response
    Wow it didn’t show them in the manual and wonder why mine only had two hoses? I guess they messed with it and lost the hoses

    Mine is a 86 year xj700 and maybe my txt is in error. I’m going to see wear these 4 hoses are hooked into the carb?

    I saw your pic and actually thought i had a different carb set up. it’s a mindblowet and i’ll look for it in the morning

    thanks Big Dan!
     
  3. hogfiddles

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

    Messages:
    14,626
    Likes Received:
    5,008
    Trophy Points:
    113
    Location:
    near utica, new york
    Dan and Van Dutch, ‘86 wont have the four coming from the tops— only the two from the overflow ’T’s.

    dave fox
     
    chacal and VanDutch like this.
  4. VanDutch

    VanDutch New Member

    Messages:
    11
    Likes Received:
    0
    Trophy Points:
    1
    Location:
    Austin Texas
    Thank you and think your right sir.

    So i’ll leave the two hoses open unplugged. I’m trying to set up carbs and using a lil gas test tank hanging from handlebar using gravity for flow. Should I just plug the vacuum line normally plugged into petcock. Or by not using vacuum to petcock does that provide enough constant gas flow? As it seems it’s starts when carbs fill but seems to run out? The only other thought is the float bowls not set right?

    any thoughts on how best to set up running without gas tank on? thanks
     
  5. Huntchuks

    Huntchuks Well-Known Member

    Messages:
    951
    Likes Received:
    395
    Trophy Points:
    63
    Location:
    East Rochester, NY
    To run without the gas tank you need to plug the vacuum line that connects to the petcock and hook up an external supply of gas to the carbs gas line. You can use an old lawnmower or snowblower gas tank or buy something on ebay.
     
    VanDutch likes this.
  6. VanDutch

    VanDutch New Member

    Messages:
    11
    Likes Received:
    0
    Trophy Points:
    1
    Location:
    Austin Texas
    Thank you

    plugged vacuum and used lil tank and left vacuum lines (2) hanging in runs terrible so i’m going to go through another carb overhaul. thanks
     
  7. Huntchuks

    Huntchuks Well-Known Member

    Messages:
    951
    Likes Received:
    395
    Trophy Points:
    63
    Location:
    East Rochester, NY
    Did you disassemble the carbs fully, break the rack? Did you replace the throttle shaft seals when you reassembled the rack? Did you remove the pilot mixture screws, etc. to clean? Did you set all the screws at the same turns from light bottom as a starting point? Your bike may run bad with perfectly clean carbs until the pilot idle circuit is set correctly (colortune) and the carbs are vacuum balanced. If you already did those steps and it runs bad, then re-clean carbs.
     
    VanDutch likes this.
  8. hogfiddles

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

    Messages:
    14,626
    Likes Received:
    5,008
    Trophy Points:
    113
    Location:
    near utica, new york
    If you use your tank from a distance, you just plug the vacuum port on the bike, and turn the petcock to PRI. Install a cheap lawn mower/snowblower/etc.... shutoff valve in the fuel line so you can stop it.
     
    VanDutch likes this.
  9. hogfiddles

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

    Messages:
    14,626
    Likes Received:
    5,008
    Trophy Points:
    113
    Location:
    near utica, new york
    Van Dutch.... when you take your rack apart to clean, you need to go at least this far.......

    98B0EF1B-9610-4034-B961-68132254A12B.jpeg
     
    noah scott and VanDutch like this.
  10. VanDutch

    VanDutch New Member

    Messages:
    11
    Likes Received:
    0
    Trophy Points:
    1
    Location:
    Austin Texas
    man you are setting me straight and on the right path as i did not breakdown rack and did not replace the orings. and clean pilots

    So i will take your advice and do that first

    I did notice running the bike at 2000-3000 rpm for 3 mins after i stopped the no 3 exhaust pipe was not as hot as 1,2 and 4. I checked all cylinders got spark
    plugs all looked super rich.

    could it be 3 is not getting enough fuel or weak coil? I’m going to buy some nee coils - Does anyone have a source where i can buy some new ones?

    Thank you for the help I owe
     
  11. VanDutch

    VanDutch New Member

    Messages:
    11
    Likes Received:
    0
    Trophy Points:
    1
    Location:
    Austin Texas
    i printed your pic in color and i will use it as a baseline i’m going to get some trays …That’s some organization
     
  12. hogfiddles

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

    Messages:
    14,626
    Likes Received:
    5,008
    Trophy Points:
    113
    Location:
    near utica, new york
    Row 1 to the left is all carb 1. Row 4 to the right.

    each row is carb 1, 2, 3, 4

    each part goes in a specific compartment, all four are organized the same. I like to stay in sequence, too.
    Screws/hats/brackets carb 1,2,3,4
    Springs/Slides carb1,2,3,4
    Etc.......

    Not doing all Carb 1 then all carb 2.... etc-

    I do it that way out of habit now, but I’ve done them so long, I know where they go. BUT— I still organize it because like-parts can get mixed up. Any slide can go in any bore, etc..... I keep parts from one carb with the same carb after cleaning and rebuild, unless they were obviously wrong....like brackets or bowls mixed up, etc......

    ymmv

    dfox
     
    VanDutch likes this.
  13. VanDutch

    VanDutch New Member

    Messages:
    11
    Likes Received:
    0
    Trophy Points:
    1
    Location:
    Austin Texas
    Always worked on single harley s/s carbs and doing carb overhauls seemed easier, despite each carb are same it’s the rails is new. Today I’m going to completely dissemble. I’ll try and get a coil pack meanwhile. Don’t give up on this old vet yet, appreciate your Valuable input
     
  14. Huntchuks

    Huntchuks Well-Known Member

    Messages:
    951
    Likes Received:
    395
    Trophy Points:
    63
    Location:
    East Rochester, NY
    VanDutch likes this.
  15. Huntchuks

    Huntchuks Well-Known Member

    Messages:
    951
    Likes Received:
    395
    Trophy Points:
    63
    Location:
    East Rochester, NY
    VanDutch likes this.
  16. VanDutch

    VanDutch New Member

    Messages:
    11
    Likes Received:
    0
    Trophy Points:
    1
    Location:
    Austin Texas
    Thanks for all the help
    I was able to talk with Dave Fox whom walked me through and now bike runs now going through fine tune sync etc

    it’s a lovely day in the neighborhood
     

Share This Page