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79 Xs 400 2LO Wont fire

Discussion in 'The Garage' started by barmstrong, Aug 16, 2021.

  1. Durney

    Durney XS400 Member

    One thing I would do is make sure the points are clean, run strips of clean white paper between the contacts of the points until the paper is clean.
    Also check for air leaks in the rubber carb mounts via cracks.
     
  2. barmstrong

    barmstrong XS400 Member

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    Thanks for the tip I will check the rubber mounts they look pretty weathered. Battery charger putting out 13.10 volts, still wouldn't start checked the time again and it had changed I don't know why im continually having to reset the time. Thanks everyone for helping me.
     
  3. barmstrong

    barmstrong XS400 Member

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    The left rubber carb mount is bad for sure, not as much suction on left as right, going to replace those and left spark plug was arcing to cylinder, noticed that last night don't see it in the daytime. Replacing them. This bike is a mess too long sitting. Thanks for the tip!
     
  4. Buddha

    Buddha XS400 Addict

    Good to hear you are finding things that are not up to par, that's what trouble shooting a problem is all about.:cheers:
     
  5. barmstrong

    barmstrong XS400 Member

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    Busy working on the Bike finally got it cranked run beautifully dialed the carb in got the idle set right, just running off of bowl gas , good it will run , spent a day cleaning out the fuel tank fixing the petcock, put the tank back on, changed the oil, worked on the master cylinder which is a lost cause, went to start it up, no start , no even a burp, tried everything, getting gas I put my hand over the carb throat and it gets wet so I know gas is there. What I've done so far, new points ,eBay used condenser, new intake ,new plugs, clean carb with BerrymanCarb Dip and ultrasonic cleaner, set time a multitude of times. Ive got gas I've got compression I've got fire, I know it will explode gas because I was checking for fire and held plug to close to spark plug hole and fire came barreling out, but my fire is not blue more yellow, its still acting like the time is off, going to go right now and check it again. Thanks!
     
  6. barmstrong

    barmstrong XS400 Member

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    Does anyone know if CM11-54 coil work with a points bike, the one on it is a CM11-50.Thanks!
     
  7. barmstrong

    barmstrong XS400 Member

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    After doing a little research and testing it appears that the 54 coils are 3.3 ohms and the 50 coils are 4.4 ohms which is apparently needed for a points bike. Interesting it will start with the 54 coils but won't rev, still working on that, and I could not even get it start with the 50 coils and they tested to be ok 4.4 primary and 17.5 secondary, if I did it right. Any thoughts!
     
  8. barmstrong

    barmstrong XS400 Member

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    Got it running and reving with the 54 coils, still some issues, flooding badly, and a new issue, cylinder gets wet around the left plug, checked it out good don't really see a crack but im sure its there, must be very tiny, not sure if these are the correct carbs, I know they are XS 400 carbs but thinking maybe from a newer bike going to tear them down today and check all the jet numbers with book specs.I can only get it to run with the screw 1.5 turns out, plugs get sooty black .Thanks for listening!
     
  9. barmstrong

    barmstrong XS400 Member

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    Got it running, embarrassed to tell the problem. I made a rookie mistake. I took the carbs back off for a second cleaning and the emulsion tubes had fallen down, I forgot to put the little brass washers back under the pilot jet. I was also running it without the air filters. Haven't found them yet, I know I have them somewhere.One thing I noticed while running it was when I rev it up it is very slow to come back to idle, and sometimes it will rev up to about 4000 rpm by itself. So still working on carb issues. Thanks!
     

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