'85 VF500 interceptor no spark

Discussion in '1st & 2nd Generation 1983-1989' started by John painter, Apr 15, 2018.

  1. John painter

    John painter New Member

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    After years of off road riding I sold my old XR600 a few years ago, it was an excellent bike, but age and reality caught up with me - kick start 600cc bikes (especially in cold climates) are for younger people. So I recently had the opportunity to purchase an '85 vf500 interceptor for $200... How could I resist? It's all there and in pretty decent shape considering it was stored in a guys woodshed here in Maine. I was inclined to believe him when he told me it was running last year but he broke the starter switch and choke cable. So I was able to replace the choke cable without much issue, the starter I have at the moment rigged to try to fire the bike up.

    This is where I'm looking for some suggestions - I have no spark. I've read several posts on interceptors without spark so I have several questions from others with more experience. The previous owner broke the starter switch so I just use a piece of wire to jump that circuit (see photo, I jump yellow/red to black/red) so the starter cranks - if I can get it to fire I'll invest in a whole new on/off starter assembly. For now, if there's something else which should be jumped to get it to fire, please let me know.

    On my coils I have 2.7 ohms on the primary side and 13.7 ohms on the secondary side, after reading through the Clymer's manual I see the primary should be 2.8 ohms and secondary 2100 to 2800 ohms. If this is the issue, shouldn't I at least see a faint spark on plug? I see no spark when I crank it. Again I'm interested in any suggestions.

    Another interesting issue, my fuel pump is not running when I crank the engine (I have unhooked the pump and it pumps fine when connected directly to a 12v battery), I had read on one of the threads here that the fuel pump will not run unless the coils are functioning correctly. Is that true? I could not find a reference to that in the Clymers manual. I would have thought the CDI might control the fuel pump and maybe two bad CDI boxes could be the issue.

    So I'm looking for some suggestions of how to approach my no spark issue.

    Thank you for any suggestions. :Help:

    starter.jpg
     
  2. John painter

    John painter New Member

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    Well, it was easier than I thought to get things going. After thinking for awhile and looking at the wiring diagram thank you @hoobatech , I realized I didn't have everything jumpered on the start switch that I should. Just in case anyone ever runs into this scenario (since I understand it's common on these bikes) and the right side controls are messed up, this is how you need to jump the switch.

    The black wire on the back jumped to the red/black on the front, and the red/yellow wire jumped to the red/black or top right contact, and if you want to see if the head lights are working blue/white jumped to the red/black.


    s2.jpg

    s1.jpg

    When that is connected this is what you get - a running bike. In person the engine sounds smoother and way quieter than my old XR 600! I don't hear any chain slap, ticking, or anything other than the very smooth whir of a four cyl engine - sounds better than my Volvo v70. :cool:

    I can rev the engine, and though it sounds a LOT more aggressive, and tach's way up there when I give it the corn, it still sounds very smooth. It's hard to get over the difference between this 4cyl 500 and the single cylinder 600 on my old XR.



    Now I just need to get the front brake unstuck.:Drum:
     
    Last edited: Apr 17, 2018
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  3. jeremyr62

    jeremyr62 New Member

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    Well done. Those F1 end cans will make it sound better then stock BTW. VF500s need lots of TLC but are a great bike.
     
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  4. John painter

    John painter New Member

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    Any pointers on the type of TLC the VF500’s need?
     
  5. jeremyr62

    jeremyr62 New Member

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    Just the engine. They can drop valves at low mileages if not looked after. (They can drop valves if looked after too unfortunately) Check the valve clearances religiously. Make sure the oil is good, the fan works and the cooling circuit is in good order. Some recommend not revving above 9K but there's no evidence either way this helps.
     
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  6. John painter

    John painter New Member

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    Thank you this helps! Now that I know the bike actually runs, I will get down to all the basics; replace all the fluids, filters, etc, etc and add your suggestions to the list. Thanks!
    :wheelie:
     
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