Replacing Needles & Seats

Discussion in '1st & 2nd Generation 1983-1989' started by Guaire, Oct 23, 2017.

  1. Guaire

    Guaire New Member

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    My previous thread was about my 1986 VF500F idling high at times. Then it wouldn't start.
    The needles were letting gas flow into the carbs and into the motor.
    I found some debris in the needle valves. Looks like the old fuel line was putting little tiny rubber chunks into the needles. They didn't show much in the way of wearing, but I'm renewing them and the fuel lines. Also, the bowl gaskets will be replaced.
    Two carb top covers were missing one screw out of four. Replacing those with Allen bolt screws, 3mm heads. The carb plate will get some epoxy material replaced along the top edge that meets the air box. Some previous owner used duct foil on it.
    I'm very open to design suggestions on the fuel line configuration. The pix show the fuel lines between the fuel tank and the carbs. The petcock hose fitting size is different from the carbs. The fuel tank is using 15/32 hose. The carbs connect to 5/16 fuel line. I would like to add an inline filter if possible.
    Hopefully, these repairs will get the 500 back on the road. Once, that happens I'll looking to replace the rubber brake lines with Spieglers or thereabouts.
    Cheers,
    Bill

    PS - My photos won't upload. I'll post this and try to add pix later.
     
  2. Diving Pete

    Diving Pete Member

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    On the older bikes I'd absolutely add an inline fuel filter..
     
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  3. Guaire

    Guaire New Member

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    Good advice, Pete. I'll have to figure out a good way to assemble the lines, with a filter. Fuel Line 1.jpg Fuel Line 2.jpg Carb #2.jpg Carb Plate Repair.jpg
     
  4. Diving Pete

    Diving Pete Member

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    That's easy - just extend the fuel line to the Y.
     
  5. Guaire

    Guaire New Member

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    Unfortunately, the spigots don't match. The carbs can use 5/16 automotive fuel line. The petcock fits a 15/32 hose. Mr. Honda isn't making fuel lines for this bike. I not only have to split the lines, I have to change sizes. The Y connector in the pics has one 15/32 and the other two are 5/16. I'm looking at fittings and adapters and hoping for a brainstorm while I wait for carb parts.
     
  6. Diving Pete

    Diving Pete Member

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    Get a longer 15/32 hose, get 1 x fuel filter to fit, cut hose & install!
     
  7. Guaire

    Guaire New Member

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    I've got a design and I have ordered parts. At the petcock I'm going to adapt the close to 1/2" spigot to a 5/16". Then everything is easy to fit: fuel filter, lines, T connector and elbow. I'll post the results when I'm finished.
     
  8. Guaire

    Guaire New Member

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    Fuel Line 1.jpg I made a fuel line setup with a built in filter. I finished it yesterday. But, still no start. I opened the drain on a bowl and nothing but air. Gotta get the gas to flow.
     
  9. Guaire

    Guaire New Member

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    This bike was in the shop. I found out the needles weren't closing the fuel flow. They are replaced. Floats are set to 7.3 mm. Replaced the float bowl gaskets.
    While the tank was off I noticed the Off On Reserve ring was 180 degrees wrong. After turning it around, I re assembled with a gasket.
    I added fuel to the tank, on the work bench. I turned it to RES. No flow. I closed off one carb connector and attached my brake fluid pump on the other one. While set to RES, I have tried to get gasoline through the petcock and into the fuel line. No go.
    The spring and diaphragm in the petcock are new. I blew air into the petcock and the air was blowing out the fuel lines. I won't re connect the tank and lines if there is no gas flow.
    What could be wrong?
     
  10. Diving Pete

    Diving Pete Member

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    If you remove the tap does fuel flow ?
     
  11. Guaire

    Guaire New Member

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    "If you remove the tap does fuel flow ?"
    Good question. I'll check that out. Can't do it right now. I'll pull the whole petcock out and see if the hole in the fuel tank flows gas.
    Thanks,
    Bill
     
  12. Diving Pete

    Diving Pete Member

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    Also have you changed / cleaned the filter in the tank?
     
  13. Diving Pete

    Diving Pete Member

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    On my nc29 the tank filter hadn't been changed since we got the bike - 2002 / 03. - lol

    I didn't even realise there was a filter. Lol
     
  14. Guaire

    Guaire New Member

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    "Also have you changed / cleaned the filter in the tank?"
    I left it out on this assembly. It had no top on it! I covered the top with epoxy, but I don't want to trust it. The pic shows the inline filter.
     
  15. Diving Pete

    Diving Pete Member

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    I use both the tank filter & the inline. Remove the fuel tap and over a bucket tip petrol through it. If it doesn't come out there's your problem
     
  16. Guaire

    Guaire New Member

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    Part #7,
    16961-MF2-000
    Where does this plug in? Both ends? Does one end go into the diaphragm and the other end into the petcock vent tube? Petcock Air Tube.png
     
  17. Diving Pete

    Diving Pete Member

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    I'm fairly sure it's a vacuum pipe.
     
  18. Guaire

    Guaire New Member

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    I did not go after the fuel tank today. I attached an auxiliary fuel tank . The motor ran. I will fiddle the fuel tank tomorrow.
     
  19. Guaire

    Guaire New Member

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    I checked the fuel tank and gas poured out of the empty petcock hole. With the tank back on the bike, it started. I can rev it for awhile then it runs weak and stops. Or, it starts and runs weakly with choke on.
    I'll look for a new/used petcock. Maybe that will work. I'm stumped.
    Thanks, Pete, for trying.
    Bill
     
  20. Captain 80s

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