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1981 XJ650 maxim intake boots YICS

Discussion in 'XJ Technical Chat' started by glennyboy, Jul 4, 2022.

  1. Huntchuks

    Huntchuks Well-Known Member

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    Looks like the ones I use on the XJ700 and XJ700X with no problems at any speed or RPM's.
     
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  2. glennyboy

    glennyboy Member

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    Thanks huntchuks I will continue with the sea foam and replace plugs at weekend, but I can feel the problem when the engine is only under a load, hard acceleration through gears on incline could be ignition ..? So far done 65 miles seafoam
     
    Last edited: Jul 20, 2022
  3. glennyboy

    glennyboy Member

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    Today i will have gone through a tank of gas re topping off this morning with two gall (and seafoam) container.... its not the spark plugs... but i did see a difference when i removed the brass in line filter.. 1/4 hose coming off petcock then into 7/64th hole to filter?... Noah has a thread going above mine...1985 XJ 700 breaking up under load.. ..could i have a bad TCI box... going back to yesterday pulling from the lights up the ramp accelerating it felt like a bop bop bop no spark but pulling through it as speed increased... will test another forty miles today..
     
  4. glennyboy

    glennyboy Member

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    After run out today i am starting to think the needle and emulsion tube are they the right ones in there or miss matched....from last owners 21 years back, i will now go from surge to stumble feeling at wot....or could be both, them parts are the only two things that regulate fuel flow...
     
  5. k-moe

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

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    I haven't exactly caught up with the thread, but I've found it to be advantageous to use a spray-on gasket dressing on the intake gaskets prior to assembly.

    @glennyboy Don't take that to mean you need to redo that work. Just food for though later on.
     
  6. glennyboy

    glennyboy Member

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    I was also thinking about the diaphragm springs if i stretch them a bit... could the pistons be lifting up to soon, too much volume of air...what have i got to loose at this point
     
  7. jayrodoh

    jayrodoh YimYam Premium Member

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    I wouldn't mess with the springs, they are really there to ensure the slides drop when needed. I'm sure they have some effect but it'd be minimal compared to the jets/slide hole. The hole in the slide and the air jets "meter" the rate that the air moves back and forth due to the difference in pressure between the top of the carb and body. The needle moves up too to allow more fuel.

    Definitely sounds fuel related, electrical drop outs have a very definitive feel. If the carbs are rebuilt correctly with the correct stock parts and fuel levels set correctly it should run well. I know that doesn't help much but I'm out of suggestions at this point.
     
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  8. glennyboy

    glennyboy Member

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    I decided to replace the spark plugs even though they looked ok, only non resistor i could get were champion N6YC ... Pulling up the onramp no stumble going through the gears, thats a plus ... not as much surge at 70 mph... its still there but waiting for the tank to get low after seafoam... i did pull the caps checked the needle jet they dont have any code numbers on any.... could they be the wrong ones?... i may have to replace the jets and emulsion tubes if things dont improve.... thanks for the help guys
     
  9. glennyboy

    glennyboy Member

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    Was the needle jet brass stock, i know my emulsion tube is brass and the jets should be stamped Y10... If no number on jet could it be wrong size mine are alloy with no letters
     
  10. glennyboy

    glennyboy Member

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    Yesterday it would not start neutral switch on gearbox, drained the oil to try and remove it...oil drain plug had black sludge on it, just done 300 miles, could this be clutch friction material, the new oil was a bit darker..... sorted the switch out in another post... This engine was not started for 21 years, the engine oil smelt bad... anyway i eventually got it running, i think the clutch plates are about done.... could this be my surge problem at higher rpm, clutch takes up drive at the end of clutch lever travel but no slipping going through the gears 36k bet that clutch has never been replaced... i have to take a look
     
  11. glennyboy

    glennyboy Member

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    clutch friction plates hard as rock will replace
     
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  12. lostboy

    lostboy Well-Known Member

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  13. glennyboy

    glennyboy Member

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    Well guys i found the problem something i failed to check from the start .. one of the coils failed the secondary test wires ok, two of the dam caps have them carbon inserts unscrewing it spring/ washer ..other coil does not have that type ... bet thats my ignition breaking down at higher rpms,. fitting new caps..waiting for new clutch.. IMG_20220724_152037384_HDR.jpg
     

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  14. k-moe

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

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    That'd do it.
     
  15. glennyboy

    glennyboy Member

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    Coil 1 and 4 had the removable carbon insert had no ohms ..cleaned them up, removed the carbon and made steel instead .... now no resistance on them ..coil 2 and 3 can not remove resistor different caps... they check out at 6k ohms so i will leave it at that until road test.... spark plugs non resistor... hope this fixes the dam surge.... if not i will have to start a new thread lol this one is getting long
     
  16. Huntchuks

    Huntchuks Well-Known Member

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    My XJ700S has resisters in two caps and none in the other two (one coil with/one coil without). This is the way they came from the factory, from all that I have read.
     
  17. k-moe

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

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    Don't start a new thread. History is important when diagnosing a problem.
     
  18. k-moe

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

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    That varied with model.
     
  19. glennyboy

    glennyboy Member

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    Well after sorting the plug caps out and replacing the clutch i was back out again, the surge was still there at 6k and up, i ran it with the surge for nine miles pulled over shut off engine... pulled the plugs ... white tips ..lean... set back off and after six miles or so the surge got worse oh shit as speed dropped ..ahh time to turn reserve on, came back to life again, but still had surge 6k so i thought thats my problem lean condition... so that surge feeling is like running out of gas but not as bad because the engine will pull through it. Pulled the choke on a bit made it rough too rich..The champion plugs seem a bit hotter so i put the NGK back in still the surge ..fixed one thing plug caps...fuel flow is good from the tank on and reserve, so whats my problem, the needle jets dont have any numbers on them ... why lean, could it be wrong size needle jets from past owners.. all the other jets are stock in the correct order, fuel height spot on, no vacuum leaks gone through a can of carb cleaner, even used propane..slides ok, stock air filter, strange why it runs perfect under 6k...before pulling carbs again i will put a 15 thou washer under each needle jet bring it up a bit make richer ... so its getting more air than gas ? if that dont work then new needle jets/emulsion tubes...:rolleyes:
     
    Last edited: Jul 28, 2022
  20. glennyboy

    glennyboy Member

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    The two holes are facing the front close to butterfly is that correct. IMG_20220728_135731819_HDR.jpg

    I see now washer under jet will not work
     
    Last edited: Jul 28, 2022

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