1984 VF1000F- very weak spark on 2&4

Discussion in 'Mechanics Garage' started by wpbarlow, Sep 20, 2017.

  1. wpbarlow

    wpbarlow New Member

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    The spark on cylinders 2&4 of my not so nice VF is very weak- will lightly spark directly to ground, but not with the plug cap on. Checked all pertinent wires for shorts/condition and they seem ok.

    Swapped all ignition parts between 1&3 and 2&4 and the good spark always stays with 1&3. Metered the pulse generator and the coils are coming in at 500 Ohms for both sets (spec says should be ~480), and the gap is within spec at .025. So that shouldn't be the problem, but I'm pretty much at a loss as what to do next.


    Totally puzzled by this, so any help would be appreciated.

    Also-- does anyone have an extra pulse generator; or know if one from another model would work?

    thanks,
    Walter
     
  2. Captain 80s

    Captain 80s Member

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    Do you mean that with the plug cap off the wire, it sparks to ground great, but when you put cap and plug on, it is weak? Sounds like it is time for new plug caps. If I read that wrong, I still think it is time for caps, you can clip the integrated cap off the wire and install new NGK caps. Do it all the time.
    [​IMG]

    You can also replace all of the wire by unscrewing at the coil.
     
  3. wpbarlow

    wpbarlow New Member

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    The spark, even with the caps off the wires is very weak. But I'm going to get some new wires anyway. The reason I don't think that's the problem is that the problem stays with the cylinders even after swapping the coils.

    After I take a day to think about things, so I don't find a cliff to push it off LOL

    Walter
     
    Last edited: Sep 20, 2017
  4. Terry Smith

    Terry Smith Member

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    If the problem stayed on those cylinders, then the fault would be in the supply or ground to the coil primary circuit. Does the 1000F use two CDI boxes? Have you checked for high resistance in the supplying wires?
     
  5. wpbarlow

    wpbarlow New Member

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    I'll be checking all that tomorrow.

    thanks,
    Walter
     
  6. wpbarlow

    wpbarlow New Member

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    Not to keep folks in suspense, but it might be a week or so before I get to this.

    Walter
     
  7. squirrelman

    squirrelman Member

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    sometimes helps to cut about 1/8 " off the wire into the ignition coil to get fresh, clean wire.
     
  8. wpbarlow

    wpbarlow New Member

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    Good idea, thanks.
    Walter
     
  9. wpbarlow

    wpbarlow New Member

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    I'm starting to believe the CDI box may be bad. A friend found this:

    http://www.v4spark.com/


    Sounds good and decent price for a pair. Anyone have experience with them?

    Thanks,
    Walter
     
  10. Mind_Surfer

    Mind_Surfer New Member

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    Walter I use those on my 500. High quality units and are programmable to some extent.

    Sent from my XT1031 using Tapatalk
     
  11. wpbarlow

    wpbarlow New Member

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    Thanks for the feedback-- I ordered a pair.

    Walter
     
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  12. slovcan

    slovcan New Member

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    V4Spark is Tom - aka dualcam - a member on our V4Hondabbs site and V4Musclebike site. He's a great guy who makes a top quality product. Even bikes that are running fine end up running better with these spark boxes.

    Cheers,
    Glenn
     
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  13. wpbarlow

    wpbarlow New Member

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    Well, delivery was certainly fast enough! Ordered Tuesday and arrived today.

    Installing tomorrow with fingers crossed.

    Walter
     
  14. wpbarlow

    wpbarlow New Member

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    Replaced the CDI boxes and that did the trick- started right up and it ran well considering it hasn't in at least 3 years. Still some relatively minor work to do; but I have high hopes to be on the road in a week.

    The clicking is the fuel pump (not the valves lol) because we're running on gravity feed.

    Here's the first start up

     
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