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Stalls when warm

Discussion in 'XJ Technical Chat' started by josh the man, May 21, 2020.

  1. josh the man

    josh the man New Member

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    Hello all,
    This is my first post on this forum, but have been doing a lot of research and still haven't found the exact issue I'm having.
    I have a 1982 Yamaha XJ550 Maxim. Its my first project bike and picked it up for $250. I drove it home knowing I would have to do work on it. The first thing I had issues with was it not shifting right. After going through the forum I found that my return torsion spring and the Shift Shaft Torsion Spring had failed. I replaced them and put it all together and it seamed to shift fine. Since then I have had the carbs rebuilt by a shop which used a sonic cleaner and oem parts. I then did a valve check and they where all way out of spec and so have just replaced the shims so that they are all now in proper spec. The bike will start up with little effort, however when its running for about 5 min., just long enough for the bike to warm up it begins to struggle at idle then after drooping some cylinders it stalls. I also notice some smoke coming from the clutch cover. Would a clutch cause the engine to stall at idle? I'm wondering if I installed the plates incorrectly. Thanks in advance for the input and sorry if this has been asked already a thousand times.
     
  2. XJ550H

    XJ550H Well-Known Member Premium Member

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    Your fuel cap vent may be clogged there is a link on how to fix it at www XJ 4ever.com end of the how to,

    Did you put oil in the bike is it at the proper level? Seeing you had your clutch out in the pot if you're unsure you should definitely look at it again
     
  3. josh the man

    josh the man New Member

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    Ill take a look at the fuel cap vent issue. as far as I can recal I put in the proper amount of oil, but it wouldnt hurt to drain and refill. During that time ill take a look at the clutch again.
     
  4. Minimutly

    Minimutly Active Member

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    The smoke is condensation, assuming you vent is open?
    If it slows as it gets hot the mixtures are likely rich at idle, you need to try screwing each mixture screw in by an equal amount to see it helps.
     
  5. SQLGuy

    SQLGuy Well-Known Member

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    I hadn't heard the oil filler hole called a "vent" before.

    Another possibility is rust/debris in the tank, clogging the fuel tap and, if you have one, the fuel filter.
     
  6. josh the man

    josh the man New Member

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    So I ran it till it stalled, opened the gas cap and tried to start it. It would start, but die right away. The petcock is new with a filter. Finally as I was about to take a look at where it was smoking I opened up the oil fill cap and it smelled like gas and quite viscous. I think its flooded at this point, which makes me think that the floats are needing adjustment. I did check the spark plugs, cylinder 3 plug was all black.
     
  7. XJ550H

    XJ550H Well-Known Member Premium Member

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    stop riding change the oil and fix the floats and needles if your lucky it is the #3 cylinder only
     
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  8. Minimutly

    Minimutly Active Member

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    I meant the vent pipe - hose being off, not the filler.
     
  9. josh the man

    josh the man New Member

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    I'll give her a go.
     
  10. Polock

    Polock Well-Known Member

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    how confident are you with the valve shim job? do the valves make more noise now that they're set?
     
  11. josh the man

    josh the man New Member

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    I'm confident, checked each valve several times before and after each shim was replaced. I also would crank it over by hand a couple times after each install to insure that it was properly seeded. Just to be clear I haven't driven it since the carbs have been rebuilt. So all diagnostics have been done in the garage. I've had plenty of time to work on it as of late so its been wrenched on almost every other day. I'm hoping to pull the carbs out this weekend as loath as I am to do it, to check float height.
     
  12. SQLGuy

    SQLGuy Well-Known Member

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    I kind of thought that, but the breather is on the opposite side from the clutch cover.
     
  13. josh the man

    josh the man New Member

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    If your referring to the breather from the crank case to the air-box, on my xj550 its on the clutch side. The smoke seems to be just oil burning off the frame as it hasn't been driven in a while, just ran in the garage.
     
  14. josh the man

    josh the man New Member

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    The hose is connected.
     

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