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1985 Yamaha 750 maxim x not starting.why?

Discussion in 'XJ Technical Chat' started by kenny&beth, Apr 16, 2018.

  1. kenny&beth

    kenny&beth New Member

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    I have been rebuilding a maximum x 1985 and tried to start it up for the first time and it just kicks on cylinder number2. It did warm up the pipe from kicking but the rest are cold. It has new plugs and I am thinking I might have plugged the coils In the wrong connections. I had this issue before years ago but if it's not that does anyone else have a idea?
     
  2. XJ550H

    XJ550H Well-Known Member Premium Member

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    1&4 cylinder from left coil pak 2&3 are from the right coil pak as sitting on the bike

    have you ohmed out the pickup coils and ignition coils.

    spark plug caps may have failed . corroded plug wires trim them a little
     
  3. kenny&beth

    kenny&beth New Member

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    I trimmed them and all new plugs. What should the coils have for resistance? It did start once for a few seconds and then shut off and know it just kicks again. Any help would be appreciated
     
  4. kenny&beth

    kenny&beth New Member

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    I also checked the wires to be sure that they are on the right cylinder and they are. So I'm thinking maybe a bad coil?
     
  5. tabaka45

    tabaka45 Well-Known Member

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    If you have spark on all 4 plugs and you have the coil wires rioted correctly then I would suspect a problem with the carbs, especially the pilot circuit. But before attacking the carbs I would try jumping it with a strong car battery just to rule out a bad battery.
     
  6. XJ550H

    XJ550H Well-Known Member Premium Member

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    XJ750-X water-cooled models:

    Pick-up coils:
    120 ohms +/- 20% = 96 ohms to 144 ohms acceptable range


    Ignition Coils:

    Primary side (input from main wiring harness):
    2.7 ohms +/- 10% = 2.43 ohms - 2.97 ohms acceptable range

    Secondary side (spark plug wires, without their end caps):
    12K ohms +/- 20% = 9,600 ohms - 14,400 ohms acceptable range


    Spark plug caps:
    15K +/- 20% = 12,000 to 18,000 ohms per cap acceptable range

    Spark plugs:
    5K ohms per plug
     
  7. kenny&beth

    kenny&beth New Member

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    I finally got it started but it started hard. It seems to be kicking off the number 2 cylinder a lot. It sounded good running no knocking or anything but I'm thinking it needs the valves set. Carbs have been gone through and cleaned and new plugs. I bought the engine second hand and was told it ran great before it was taken out many years ago. Anyone know of any videos showing how to set the valves on the x
    I've done a lot of other bikes but they was very simple. I know that the cams must be lifted but I don't know the specs etc. Thanks for the help
     
  8. Timbox

    Timbox Active Member

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    Here is a vid that will help you a little but there are a few more out there now days on the tube. On the side of the vid page are many other "X" vids, enjoy.


    You said the carbs were cleaned, but were they taken to "Church" I only ask because my throttle seals on my "X" needed to be change out after I thought my carbs were clean too. I could not get my "X" to idle very well and the throttle seals were the reason.

    As for the shims, make sure you get a manual of some type, download one or get a hard copy. Have a good place to work on the bike and read and re-read how to check the clearance. Once you start to remove the cam holders, make sure you stick something "rag" in the space with the timing chain. Hate to have you lose anything down the timing chain channel.

    Do a search on here and you will find different vids and how to stuff along with other threads of people with "X" model. It is a different animal to work on ;)
     
  9. kenny&beth

    kenny&beth New Member

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    Just wanted to update everyone. I got it running and it starts amazing know. The motor hasn't been run in many years . I'm really happy with it and know I find that it will sputter on one cylinder once in awhile and when I give it a little throttle it'll clear up and then it returns a little while later. I think it's the number 1 cylinder . I also notice that I have a little trickle of Preston coming out from behind the trim that bolts on the side of the cylinder. When i remove the two bolts theres a factory hole where it's just dripping a little and then it'll stop and then start again and stop. Any ideas why? Thanks
     

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