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Ok guys, this one's got me stumped

Discussion in 'XJ Technical Chat' started by tskaz, Mar 18, 2012.

  1. tskaz

    tskaz Active Member

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    Got the throttle shaft seals from Len and got them installed yesterday.

    Bench sync
    Float levels
    Re-install carbs

    So today I fill the tank and charge the battery.

    Running sync on 3/4, then 1/2, then 2/3, bike fully warmed up.

    Then I start my colortune, and that's where my problem is.

    Cylinders 1,2, and 3 went fine. I get to 4 and I have no fuel burn at all.

    The plug was black, way rich, so it was getting fuel before I installed the colortune.

    I started at 2.5 turns out. I had to turn IN 3/4 turn just to get orange flame in the colortune.

    Flame is orange from bottomed out to 1.75 turns out. Any farther than 1.75 and I get no flame at all.

    Places to start looking?

    I've already checked for fuel in the bowl. That's actually what made me try going in on the colortune.

    Left screw at 1.5 turns and re-installed regular plug. Exhaust now gets HOT, it wasn't before.

    That's all I tried before I came in. Needed a break LOL
     
  2. dmccoach

    dmccoach Member

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    These are my guesses others will know more

    Oring and washer installed right way on that pilot screw (on that cyl)
    Fuel level not ok on that bowl
    "choke" needle not seated on that carb
    Float needle not seating on that carb
    Intermittent spark on 4
     
  3. wingnut63

    wingnut63 New Member

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    hmm interesting maybe the wire from colortune plug didn't make good connection on number 4...those wires that come with the kit look kinda weak to me...im only guessing here
     
  4. tskaz

    tskaz Active Member

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    Thanks for the input Coach,

    I didn't replace the orings on the pilot screws. The orings were ok when I went over the carbs this winter. Could be a possibility, but wasn't leaning that way.

    I haven't checked the float levels yet, bu will check 4 against the others when the bike is cooled off. I didn't want to dump raw fuel on a hot engine.

    Enrichment circuits are perfect. All 4 seat and flow correctly.

    Spark on #4 is good, the colortune shows consistent and bright, just no fuel burn after 2 turns out.

    Probably should replace the orings just for the hell of it anyway.

    The bike sounds great when all 4 are banging away. Just so close after doing so much work on this one that I want to take it slow and methodical so I don't get frustrated.
     
  5. tskaz

    tskaz Active Member

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    Wing,

    Colortune works great. Nice bright consistent spark.

    Oh and just FYI for anybody reading....When you pull the plug cap off the colortune, then try to snap it back on, with the bike running...LMAO....there's a VERY good chance you will get a wake up jolt.
     
  6. RickCoMatic

    RickCoMatic Well-Known Member

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    Check:

    #4 AIR Jets for correct Position:
    [​IMG]

    Pilot FUEL Jet:
    a) Seated
    b) Size
    c) Open
    d) Passages open

    Pilot Mixture Screw:
    a) Correct install, (Screw-Spring-Flat-O'ring)
    b) O-ring seated. (Not on-end, flipped above flat, split, tilted.
    c) Extra O-ring? PO left flattened-out O-ring in hole.

    Vacuum Petc0ck Line attached to Manifold with Leaking Petcock Membrane.

    Bad Plug Wire.
    Push 3" of Solid Copper Ground Wire from 3-Wire Household stock ... up the Middle of the Plug Wire as far as you can.
    Sand a POINT to help it move
    Smear it w/ Vasillene or Saliva.
     
  7. tskaz

    tskaz Active Member

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    Air jets correct size and location. Actually double checked this when I pulled the carbs back off to replace the shaft seals.

    Pilot fuel: pulled, cleaned, seated, correct size, free flow all checked and cleaned when I did the rebuild over the winter.

    All 4 vac ports capped off, using aux fuel setup for sync and tune.

    I don't see how a bad plug wire could cause this condition. Like I stated earlier, the colortune shows a perfect spark on cyl. 4, just no burn past 2 turns out.

    So, so far it looks like it's in the mixture screw itself, or possible incorrect float height.

    At least it's #4 so I can check them while on the bike.
     
  8. bigfitz52

    bigfitz52 Well-Known Member Premium Member

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    Why didn't you verify the float levels before beginning? You know how important they are.

    Float levels or the mixture screw's o-ring is shot; OR that particular carb didn't get all its passages clean...
     
  9. tskaz

    tskaz Active Member

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    Verified Float levels (with fuel of course) before first install.

    Re-verified with this install because I had to break the rack apart to install the shaft seals.

    I actually went up a hair on 1 and down a bit on 4, 2 and 3 were still spot on.

    That's the part that is baffling me. I just did the whole sync/tune/sync/tune thing two weeks ago and didn't have this problem. But I discovered leaking shaft seals, so after I got the parts from Len I started the whole process over.

    I'll pull the screw and oring when I go out to hook up the tender tonight.

    I don't think it's the float level, but I'll still double check it anyway.
     
  10. hogfiddles

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

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    Yeah, it almost sounds like the mixture screw has the o ring and the flat washer reversed and you're sucking too much fuel. Or, the enricher plunger isn't going all the way back down and you're sucking too much fuel.

    If you verified the jets, needles, etc....... re-check the stuff at the back end of the carb.

    Dave F
     
  11. tskaz

    tskaz Active Member

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    Pulled the screw, spring, washer, and o-ring.

    Everything looks fine. No cut or marks in the o-ring.

    Re-installed everything and will retry colortune tomorrow after work.

    When I re-installed the mixture screw, I turned it all the way in. It looked to be slightly deeper than when I bottomed it out the last time. ANd it bottomed in a different orientation.

    Looks like I might have had a bind in the spring or the o-ring was slightly off when I re-installed them initially.

    So tomorrow I will start again, at 2.5 turns out.

    Thanks for all the input. I'll post the results tomorrow, good, bad, or ugly.
     
  12. dmccoach

    dmccoach Member

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    Turning the pilot all the way til it seats can be nerve racking bec. if you bottom it too hard you can damage the seat - yet while turning it down you may feel several "hangs" due to dirty or slightly dented threads and therefore you stop before bottoming out - also be sure the needle is not bent - roll it on some glass

    Be sure that float needle is seating and you're not dribbling gas down the throat... Also IMHO the choke plungers can be tricky because if the arm is off it will hold the plungers up a very tiny amount and appear seated - open close the choke on the handlebar then duck under with a screw driver and press down on the plungers and if you see even a "micro movement" fuel is sneaking by when you assume there closed

    Swap plug wires 1 and 4 (move 1 over to 4) just for poops and giggles to eliminate that possibility
     
  13. iandmac

    iandmac Member

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    A couple of things that have bitten me during this process ...

    Check the plunger actuating shaft and tangs on the enrichment valves ... if one of the tangs on the shaft is even slightly out of line it will hold the valve open and make that carb run rich. You have to get it so they all move precisely together and with the choke in the off position there is a little free play. There's no spring on the cable ... just the springs in the plungers and they have to take up the cable slack .. at full travel there's not a lot of spring force there. Lube the cable and make sure it all lines up.

    Check your cable routing ... my bike would run rich after coming out of a left corner ... it took ages to find the "choke" cable was binding whenever the handlebars went full travel left. Re-routing to the diagram in the book fixed the problem.

    Disconnect the cable while tuning to eliminate it and then you'll know if that was it or not.
     
  14. tskaz

    tskaz Active Member

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    I'm quite positive it's not the enrichment circuit, but that's a good idea. I will do that when I get home.
     
  15. tskaz

    tskaz Active Member

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    Ok, so I get home and go right out to the shed. Well almost, had to kiss the misses first.

    I level the bike (pain in the a$$) and check the float levels. Level across the board, except for 4. Slightly higher.

    No problem. Pull the bowl, touch the tang, re-install bowl.

    Re-check levels. All is good.

    Start her up (fires right off) and warm it up a bit. Go down the drive and back, etc.

    Back to the shed. Install colortune on #4 cyl. and disconnect enrichment cable. Start bike and push down on all 4 enrichment valves, no movement. That's good.

    Check the colortune. At 2 turns out, nice blue color. Cool. Then the bike starts dying. Look up at the petcock. The bald guy forgot to turn it on prime. Switch to prime, wait about 30 seconds. Good idle, chek the colortune. Orange. Damn it!

    Ok, it's getting too much fuel. Why? So I shut her down and pull the bowl.

    Hold the float up and turn tank to PRI, fuel doesn't flow. Let go, fuel flows. Ok, so the needle is seating correctly.

    Just for s**Ts and giggles, pull the float pour fuel into the carb bowl, place the float in the bowl. Wallah, buoyancy at work! So the float floats.

    Re-install float, re-install bowl. Start her up again. Check colortune, damn thing is still orange. Turn screw in 1/2 turn, to 1.5 turns out. Not orange, but not blue either. Ok. Blip the throttle (around 2,000RPM). Wow. That's the blue I want. Bike goes back to idle and instantly orange, then settles down to not orange, not blue.

    Ok, WTH is going on!?

    Float level good, float floats, valve seats, mixture screw good, enrichment circuit disconnected. Bike sounds perfect.

    So I steady the idle at 2,000RPM and take a peek at the CT, perfect blue, steady, consistant. Idle back down, orange, then in between colors.

    Shut her down, go have supper. Think.

    After supper, re-install plug. Install tank. Install seat. Take her down the driveway (no insurance yet, and here in Michigan road+no ins+police=jail).

    Sounds beautiful. Rev to 8,000 and she screams. Steady 2500RPM and she doesn't stumble at all.

    No clue. So when I get back to the shed, it dawns on me. 2,000RPM is charging RPM. Battery? Plug it in to the tender, and it's not fully charged. Can't find my multimeter, so I don't know the volts.

    I'll try again after the tender says it's a full charge. But would a weak battery make it run rich?

    All I can think of is that it doesn't have enough voltage to completely burn the charge on #4.

    Opinions?
     
  16. wingnut63

    wingnut63 New Member

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    tskaz,
    it seems its only at idle....... could it be butterfly closed down or opened little more than the others on 1,2,3,....sounds like you got it running pretty good otherwise!!....man you have checked recheck every thing it seems....maybe if you have the CT in #4 agian you could try moving the adjustment screw to see if it make any diffents......i dont know just a idea thats all...
     
  17. dmccoach

    dmccoach Member

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    I can't remember but did you put new coils in?

    I mean with new coils and wires, there shouldn't be a wire or coil issue --

    NONETHELESS -- simply swap 1 and 4 plugs -- pull plug #1 off -- pull #4 off - Now swap -- put #1 wire into 4 plug, then put #4 wire into color tune, but test in #1 cylinder, if you have the same issue, it is either a plug wire (#4 wire) or coil issue (the 1 and 4 tower)... Then to be sure test color tune in #4 cylinder with #1 plug wire if you wish, but I bet #4 behaves OK with #1 plug wire

    Resistance test your towres

     
  18. tskaz

    tskaz Active Member

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    I'm out of ideas at this point so I'll try it when I get out of work.
     
  19. RickCoMatic

    RickCoMatic Well-Known Member

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    Even though don't think its the Enrichment Valves; it wont hurt to go-over them.
    You can get a "Finer" Adjustment of the Cable by adding a couple of layers of Heat Shrink at the Cable End.
    It's sometimes helpful to "Flatten-out" the Pinch-plate on the Choke Cable Bracket to keep the Cable from moving.

    Careful attention should be paid to the Enrichment Plunger "Top-Hats" the Fingers surround and lift.

    The Top-Hats become "Tilted" when angry P-O's mash on the Choke Lever when the Bike is hard to start.

    The Activating Finger should be "Synchronized" for Lift.
    The Fingers Parallel.
    The Slot-width uniformly curved and formed alike.
    ::: A Tablespoon or Teaspoon works well as a Tool to check curvature and as a Form to bend misshaped Fingers back into correct geometry. :::
     
  20. Hamster

    Hamster Member

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    Disclaimer: I have never overhauled the carbs on my own XJ. I do have some familiarity with this stuff though. That said, the one variable that this issue started with is that you replaced the throttle shaft seals. And the issue is at one position of that shaft (idle) and not at others. I would wonder about a leak there associated with that one position. Perhaps the old unlit propane test near those seals with it idling? My best 2 cents at the moment. I sure am curious to hear the solution when it comes, cuz this is a heck of a puzzler.
     
  21. MercuryMan

    MercuryMan Active Member

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    I would have bet on it being your pilot being off somehow. It seems that you have eliminated that possibility.

    I know with mine if the battery is weak at all it won't run right and usually doesn't want to start then either. It seems the coils (stock) get just barely enough juice from the battery to function, and when the V drops they are the first to go. So yes it does seem possible to cause issues at idle, especially since these older coils develop resistance at varying rates so your 1,2, & 3 might all be better circuits and 4 might be the weakest link. Have you checked your secondary resistance? You could also pull your plugs and in the relative dark gauge how much blue spark you are getting from each one to see if there is a noticeable difference.
     
  22. tskaz

    tskaz Active Member

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    Came home today and unplugged the tender.

    Installed colortune to #4.

    Started the bike on enrichment, then down to idle off pilots.

    My eyes on the colortune the whole time, just to see if there was a difference from enrichment to pilot idle.

    Bright orange flame on enrichment.

    On idle the orange went away. Perfect blue flame. The mixture screw is only at 2 turns out, but it will do until I can get it on the road for a test run and plug chop.

    And now I feel like a dumba$$.

    I'll be taking the battery for a load test tomorrow. Got a football meeting tonight.

    Enrichment circuits all checked out ok, plug wires and caps ohmed out good, same result on 1 and 4 wires with them switched.

    So the lesson for today boys and girls is:

    Charge the battery when you take a break in between carb sync and colortune. I must not have had the battery at a full charge when I started, and of course while doing all this the bike was at idle, not charging. It must have run the volts down just enough to mess with my mind.

    Oh, battery shows 13.1 volts non-running, 12.4 volts running, 14.3 volts at 2,000RPM.

    Thanks for all your advice on getting this silly little problem solved.


    Can't quite visualize what you're talking about with this...have an illustration? I'm intrigued.
     
  23. dmccoach

    dmccoach Member

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    Good news good job
     
  24. Polock

    Polock Well-Known Member

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    this is where a switch to shut off the headlight comes in handy, just for tuning. also look in your box of springs for a compression spring that fits over the choke cable between the arm that moves and the cable clamp, that will help the plunger springs close.
    a chrome spring would be trick but i never found one
     
  25. Rastacia

    Rastacia Member

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    That springs a good idea , gonna do that tomorrow.

    Funny i should just read this thread as I have just come in from the shed . I have just molested my bikes wiring loom and got rid of the indicators /clocks complete left hand switchgear and I have narrowed the loom down to roughly 20 odd wires . i was suprised as to how well the bike started up and idled so i guess your right , with less strain on the ( old) system it gives a bit more juice to the ignition sytem . Hopefully even more tomorrow when I replace the fusebox .
     
  26. RickCoMatic

    RickCoMatic Well-Known Member

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    The Cable End Bracket and the way the Bracket captures the End of the Enrichment Cable is pretty Low-tech.

    On some Bikes the Cable is practically falling-out of the Pinch-plate.
    The Pinch is a Stamped Part that often requires some doctoring to persuade it to HOLD the Cable End from slipping.

    To have the "Vee" GRIP the Cable End and HOLD if from slipping, ... you can also increase the Diameter of the Cable Sheath with:
    a) TAPE around the Cable End
    b) Layered Shrink Wrap
    c) Short, Tight-fitting Hose (Split along a Bias Cut. Opened-up and placed around the Cable-end. Closed. Squeezed tightly around Cable before tightening-it-up in the Vee-Tab.
     
  27. tskaz

    tskaz Active Member

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    Ah, now I understand. Thanks Rick, I just happen to have a whole box of heat shrink tubes.
     
  28. biggs500

    biggs500 Active Member

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    Nice detective work. I'm having a similar issue with #4 and I know for a fact my battery is weak. I'll be trying a new battery soon. Thanks!
     
  29. bigfitz52

    bigfitz52 Well-Known Member Premium Member

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    You can do the heat-shrink tubing thing at the top if it's prone to falling out up there too...

    I just smacked my clampy-plate piece with a hammer on a flat surface and it grips fine now.
     
  30. Ground-Hugger

    Ground-Hugger Member

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    Hammers make everything fit and work better Fitz!!
     

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