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XS400H 1981 I THINK IS CARBURETORS PROBLEMS!

Discussion in 'The Garage' started by fabricio, Oct 28, 2022.

  1. fabricio

    fabricio XS400 New Member

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    bolivia
    Hello, I am new here and it is also my first motorcycle that I restore and it is breaking my head a bit, I still did not want to ask anything in the forum and base myself on all the information that I found in it, but I cannot get my motorcycle to run.
    First I corrected the ignition timing, I checked the electrical system and I did it again, I checked the spark and I adjusted the tolerance of the valves as indicated by the information I found in the forum.
    second I did a complete cleaning and tuning of the carburetor, I did this 3 times, third I was a little tired and I restored the carburetor by changing all the parts and jets for new ones that I found on eBay.
    but even so, the carburetor does not work, and when it worked in the first cleaning only one piston worked, now after completely restoring it and tuning it no longer starts and I have to cover the air intakes for a few seconds so that it starts the motorcycle for a few seconds but after that, it turns off. please if someone can help me or guide me with advice or similar experiences I appreciate it.
    the carburetor is the bs34 model and the bike is xs400 from 1981
    attached I will leave some videos and photos, the carburetor is completely tuned with information from the forum and has a thorough cleaning
     
  2. tstidham

    tstidham XS400 Addict

    If blocking off the air allows it to run, you probably have the idle jet screws turned too far in or you may still have a blockage in the idle circuit passages in the carbs. I had a similar issue on my carbs and also cleaned them a few times. What finally worked for me was using a single strand of multi strand copper wire and using it to ream out the pilot jet. Despite spray cleaning it, i was able to push out a little more gunk from the jet. I also removed the idle jet screws and ran the copper wire through the carb passageways and more brake cleaner to get them really cleaned out. For adjusting the idle jet screws, i started with 2 turns out and adjusted them out from there. Keep turning them out 1/4 turn at a time to raise the idle rpm but you also want to lower the idle speed screw as well if the rpms get too high. If the idle drops when you turn it out, you've hit the proper idle mixture. So turn them back in 1/4 to 1/2 turn then set your idle speed screw to get about 1200 rpm.
     
    CaptChrome likes this.
  3. CaptChrome

    CaptChrome XS400 Addict

    In addition to what @tstidham has listed, I would also make sure that your starter circuit is working. Make sure that you have the choke (enricher) pulled out either halfway or all of the way. There is a starter jet on the carb that needs to be clear also, it is in the float bowl. Make sure that you can blow air or cleaner through it as indicated below. The start jet is pressed into the passage so do not remove it.
    Start jet passage.JPG
     
    tstidham likes this.

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