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650j no start

Discussion in 'XJ Technical Chat' started by Fry, Oct 17, 2020.

  1. Fry

    Fry New Member

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    Hello I'm helping my neighbor get his 650j running again. It's cranking over and appears to have spark. But the best I can get is occasional popping using starter fluid. I want to say the timing is off but I can't seem to check it as my timing light wont trigger off the sparkplug wire.

    From my understanding is it was running in March and started sputtering and died. And now won't start. I have checked spark on 1 3 4 and the spark tester is flashing. 2 and 3 plugs get wet. And 4 was dry but black.

    I just need a starting point. But after reading I'm guessing the carbs are a bit finicky.

    Thanks
     
  2. k-moe

    k-moe Pie, Bacon, Bourbon. Moderator Premium Member

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    1. Assume that the previous owner is lying.
    2. Assume that the previous owner is lying ( I say this not knowing if your neighbor has owned the machine for along while or not).
    3. Read This First
    4. Check valve clearances. Nothing else you do will be of help if the valves aren't in spec.
    Bigfitz's AIRHEAD VALVE ADJUSTMENT with Pics - parts I & II

    5. Carbs are finicky, but when treated well and set up properly they will be good for a long time (a decade at the minimum if cared for properly and the machine ridden).
    Inside your Carbs
    Clean Your Own Carb's - The Whole 9 Yards - by: Rick Massey
    IN THE CHURCH OF CLEAN
    Why you should replace butterfly (throttle shaft) seals.
    Replacing your Hitachi throttle shaft seals
    Setting the fuel levels
    HOW TO: Bench-synch your carbs

    6. (which should really be #1).
    Why You NEED TO REPLACE Original brake lines w/pics
    Why you need to rebuild your caliper and M/C w/pics
     
    Last edited: Oct 17, 2020
  3. Minimutly

    Minimutly Active Member

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    Check valve clearances - if you have some it should at least start.
    Remove all plugs and spin it over - check for sparks - this needs you to ground both plugs on each coil (all four then), so not a simple as it sounds, but you need to do this to make sure the supply, pickups, transistor ignition, coils and leads are ok.
    If you have spark, put clean plugs in, spray a second or two's easy start in each carb (filter out), it should start, run for 3 seconds, then stop.
    Then check each carb bowl by opening the drain screws and measuring volume in each one (petcock not on prime).
    If you have clean fuel in each one it should start.
    Then do everything properly to keep it going long term.
     
  4. Franz

    Franz Well-Known Member

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    If it has the original Yamaha fusebox change it for a blade type one.
     
  5. Fry

    Fry New Member

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    The fuse box has been changed to blade fuses. I forgot to mention we have 120psi on the compression test.

    According to the factory service manual we have 2 bad coils. The coil for 1-4 reads fine on the primary but the secondary reads 21k vs the 10k spec. The coil for 2-3 again primary is good. I have no continuity on the secondary. Both pickup coils tested in spec and wiring is testing good also.

    One thing I noticed in the manual it's showing plug caps for 2-3 at 10k each and 1-4 should be 5k. Currently all the caps are 5k.

    2 new coils have been ordered.
     
  6. XJ550H

    XJ550H Well-Known Member Premium Member

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    all caps should be 5k. 10k is a missprint.
    find proper specs here
    The Ultimate Relay, Switch, Sensor, and Diodes Guide.

    are you testing secondary with or without caps in place?
    all shoukd read 11K without caps if caps are installed secondarys will read 21K.

    on coil with no reading trim back spark plug wire, ends may be corroded
     
    k-moe likes this.

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