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'81 550 Seca bogging down then stalling

Discussion in 'XJ Technical Chat' started by steve06118, Sep 9, 2009.

  1. steve06118

    steve06118 New Member

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    Hey guys, hope you all are enjoying the last couple months of riding season. I, on the other hand, have not had a chance yet. My 550 Seca will start fine and run smoothly for about half a mile, then it starts to bog down until it eventually stalls out. Once right before it stalled it backfired. Once it stalles it will not start unless I wait about 10 - 15 minutes.
    Any ideas guys? I am a new rider so I don't know a lot about how these bikes run. Also, how easy is it to sell a bike like this? Would I get a decent amount selling it as a parts bike? Thanks for your help.
     
  2. helmet

    helmet Member

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    On 2 wheels... just lost my hat.
    is it idling when it stalls out?
    the characteristics of the bike change dramatically when they warm up.
     
  3. steve06118

    steve06118 New Member

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    It mostly stalls when I downshift into first while coming to a stop.
     
  4. KrS14

    KrS14 Active Member

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    Sounds like it's running rich, and after it warms up it stalls. Rich when cold will make her run good, but when warm, it'll act like yours is. What do the plugs tell you after it stalls out?
     
  5. protomillenium

    protomillenium Member

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    This sounds like the right track, but I also think you've got a lot to learn about how to keep a bike in tune. You could be like a new guitar player who's first guitar just went out of tune. You're going to have to buy the manual and do some studying. You can do it! Bill
     
  6. steve06118

    steve06118 New Member

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    Yeah, I definiely am a noob with bikes. I did take the plugs out after stalling out and the number 1 and 2 plugs look ok, but 3 and 4 are black and covered in carbon fouling. Could I just adjust the fuel mixture screws? I read in my manual that these screws should not be messed with and the protective plugs are still covering them on my bike. Kinda nervous to take the screws plugs out to adjust them. By the way my bike has about 22k miles on it and I just installed a new battery, brushes, air filter and did an oil change with a new filter.
     
  7. Ternk

    Ternk Member

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    I would touch those idle mixtures screws until you buy the adjustment tool for it first. chacal sells it on here. A normal screwdriver will strip those things so fast and so easy. Trust me, I stripped two of mine :(
     
  8. protomillenium

    protomillenium Member

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    Because the idle mixture screws have never been tampered with that may not be the problem. Check the power of the spark for those plugs, check their wires and connectors, try swapping the 1 and 4 wires to see if the fouling follows the wires, same for the 2 & 3 wires. This is all in the service manual trouble shooting procedure. Look in there for what to do next. You may have to take out the carbs for a complete cleaning.
     
  9. bigfitz52

    bigfitz52 Well-Known Member Premium Member

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    Yes it sounds like your carbs may need some attention.

    HOWEVER: Your symptom is consistent with a plugged gas cap vent or a crack in the petcock vacuum line. The next time this happens (or you can make it happen) open the gas cap and try to start it right away.

    Inspect the vacuum line (the smaller one that connects the petcock to the #2 intake manifold) for cracks or splits.

    The backfire tells us the engine was running out of gas.
     
  10. leadboots

    leadboots Member

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    what kind of plug are you running? I would think a carb adjustment would be a good thing. when was the last time the carbs were cleaned?
     
  11. steve06118

    steve06118 New Member

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    I really appreciate the input guys! Well, I checked the fuel vacuum line and it looks good. I recently stripped the fuel tank interior since the liner that was in there was starting to peel. I coated the tank with Kreem and it looks brand new inside but there was some residual Kreem coating the inside of the tank cap so I took it off and cleaned it the best I could but it still may be clogging the vents. I'm thinking of putting in an in-line fuel filter from Lowes which was originally made for a mower, but should work on this bike.
    I am using NGK D8EA plugs which are what the manual suggests. I am not sure when the carbs were last cleaned since I bought this bike a month ago and don't know alot about its history. What do you think? Take the bike somewhere to get the carbs cleaned or do it myself?
     
  12. helmet

    helmet Member

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    On 2 wheels... just lost my hat.
    anyone can pay to have it done.
    I would take the time to do it yourself and learn about the bike.

    once it's done, there is a lot of satisfaction.
     
  13. steve06118

    steve06118 New Member

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    Yeah maybe I'll do it myself Helmet. It sounds like a decent job and it definitely would be a learning experience. The reasons I got this bike was: it was inexpensive, looked cool ( I personally like the older style bikes ), I wanted an easy bike to learn on since I just got my license in July, and I wanted a bike that needed some work in order to gain experience.
    I also noticed some dry rot on the intake manifold where the carbs meet the engine and was wondering if some liquid electrical tape would be a good quick fix.
     
  14. helmet

    helmet Member

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    On 2 wheels... just lost my hat.
    black RTV will work too
    even if they dont look like they are cracked all the way through, fill them anyway
     
  15. bigfitz52

    bigfitz52 Well-Known Member Premium Member

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    You'll probably need to take the gas cap apart and clean out all the little passages and holes. Just be sure not to lose the latch plunger springs in the process.

    I know this one might sound daunting, but at 22K you really need to get in and check those valve clearances. If it was ignored, you're just now getting to the mileage where it will start to hurt the motor. It's not difficult but it is very necessary. http://xjbikes.com/Forums/viewtopic/t=14827.html

    You should check/adjust your valves and then do a compression check before trying to begin any serious carb tuning; a tight valve will make it nearly impossible.

    Since you just took over the bike, be sure to check your rear brake for delamination ASAP. It's a common occurance if the bike sat for any length of time and can have disastrous results. http://xjbikes.com/Forums/viewtopic/t=15874.html

    Get yourself a manual and tackle the bike yourself. Even if you manage to find someone to take your money to work on it, they may or may not know what they're doing. A lot of shops won't touch these old bikes, and that is actually a good thing.
     
  16. steve06118

    steve06118 New Member

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    Thanks for the info!! I do have some questions regarding the valve job. How do you know if the clearances are out of spec? Is there a measured range the valves need to be within? Also where do I get the tool that holds the valves open while you remove and replace the shims? All in all, this looks like a very straight forward and easy enough job. The tutorial you posted with the pictures is definitely going to make it 100% easier though. I just wish I had known about valve clearance andjustments when I was replacing the cover gasket.
     
  17. bigfitz52

    bigfitz52 Well-Known Member Premium Member

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    If you go back and read the tutorial it explains how to check the clearances, and the chart (with the specified ranges) is also included. The chart is also very handy for helping figure out which shim you need but remember it's pure metric.

    Intake valves 0.11mm-0.15mm; exhaust 0.16mm-0.20mm.

    Checked with the cam lobe at 180* from the bucket (sticking straight up, you measure the clearance from the cam lobes' "heel.")

    "The Tool" is commonly available; chacal carries them as do Bike Bandit, etc.
     
  18. steve06118

    steve06118 New Member

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    OK so I completed a valve clearance job. All valves except one needed changing. Then I took off the carbs and completely cleaned them replacing the o-rings and float seats with new ones. Synced the carbs and threw them back on.
    The bike would not start at all. Previously, I had run seafoam through the bike, so, that mixture was still in the tank. I drained the tank and refilled with fresh gas while replacing the inline fuel filter. The bike started right up and I was able to adjust the idle to about 1200 rpm at normal temperature. I rode it for a block then it died again. Now, at normal temperature, if I have the choke lever open (all the way to the left) the engine will start and rev very high, but if I start closing the choke it dies immediately.
    Any thoughts? I was thinking that junk in the tank is clogging the filter, but that fast???? The interior of the tank is very spotty.
     
  19. JFStewart

    JFStewart Member

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    Sounds like you did't get the carbs clean enough. It may have looked clean but did you check all the orfices and passages with solvent and air. My jets looked clean until I held them up to the light and looked though them. I couldn't see light in the opening. Had to resoak and use higher pressure air to clear them. I started at 30psi which cleaned most but had to go to 125psi to eventually blow the blockage out of 1 jet.
     
  20. markie

    markie Member

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    Your original fault is quite similar to what I have experienced on my bike.
    Try running the petcock in "Prime" (Remember to switch back to run when you stop).

    If the bike runs ok, then that could be the issue. Vacuum leak or petcock not opening properly.
     

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