Carb masters: 3rd gen still will not idle on pilot circuit with butterflys closed. Flooding into cyl

Discussion in 'Mechanics Garage' started by flummerylove, Sep 6, 2011.

  1. flummerylove

    flummerylove New Member

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    kennybobby has been an absolute incredible generous help with my issue. The problem has improved greatly but still not fully dialed. MPG on full tank is 150. Since I have owned it, the bike has always flooded thru the 3 transfer ports. Oil continually gas fouled. Plugs black/medium brown, but still too rich. All jets/needle stock. I have cleaned carbs 8x or more, last 2 attempts were based on kennybobby & squirrelmans knowledge. Verified all passages are clear with appropriate gauge wire. Boiled carbs in lemon juice on last attempt and rodded all passages again. What might be restricting the pilot circuit from proper idle? Choke is not stuck. Will not start with choke and butterflys closed. I am about 3/4 turn in on the "throttle stop" screw for idle about 800-900 rpm and mix screws closed. Arg..
     
  2. kennybobby

    kennybobby New Member

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    Use the choke [i.e. Pull the lever to open the start enrichment circuit] to get it started if it is needed--that is how it is intended.

    The mixture screws must be open in order for a bike to idle. That is how the carburetors are designed to work. You will never get a bike to idle properly with the mixture screws closed, so why do you continue on this path of trying to run with them closed?

    If you want to dial in the mixture, attached are the factory service manual procedures.
     

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    Last edited: Sep 6, 2011
  3. tinkerinWstuff

    tinkerinWstuff Administrator Staff Member

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    Enrichment circuit is opened or closed in attempting to start?

    Using correct terminology helps - a choke is a butterfly valve that restricts airflow and results in a richer mixture. Closing a choke makes for a rich mixture.

    Closing an enrichment valve makes for a leaner mixture as it closes the plunger that allows extra fuel to flow.
     
  4. flummerylove

    flummerylove New Member

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    Enrichment circuit is closed.
     
  5. flummerylove

    flummerylove New Member

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    Understood. However bike will not idle at any position of mix screws. 1.5 turns out or closed, bike will not idle without using throttle stop screw. 2 days on this do far. Super frustrated
     
  6. kennybobby

    kennybobby New Member

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    i feel your pain and it's killing me.

    Here is what i would do to get it running and go ride:
    1. Open mixture screws to 1-1/2 turns out.
    2. Turn the throttle stop screw ~1 turn in to slightly open the butterfly throttle valves.
    3. Use the start enrichment lever to open that circuit to get the bike started--don't be surprised if the engine speed jumps on up a couple of thousand rpms. Close the enrichment circuit after it starts up and see if it idles, albeit at higher than spec speed.
    4. Now lower the idle speed rpm down to something reasonable, 1000 - 1200, by backing out the throttle stop screw slightly. If it will idle at 1000 great, if it wants 1100, then so be it.

    It should be possible to ride the bike at this point. If fine tuning of the mixture is desired, then investigate the procedure attached up above.

    If anyone has additional thoughts, or i'm on the wrong track, please jump in here and help get this bike running...
     
  7. tinkerinWstuff

    tinkerinWstuff Administrator Staff Member

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    are the carbs balanced at all? if the balance is too far out of wack, maybe it's causing it to not idle without applying throttle.....

    just grabbing at ideas

    my bike runs flawlessly and requires the enrichment circuit to start a cold motor even on warm days

    are the washer and o-ring present on the pilot adjustment screw? (idle air mixture screw per the keihin literature...)
     
  8. ridervfr

    ridervfr Member

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    My starting ritual for my 3rd gen bike is this: I thumb the choke lever about half to three quarters down on the bar, I then simultanously hit the starter button while giving its just a CH (cunts hair) throttle. I flip the choke off after about 20 seconds or so and give it some gas and clear the carburetors. Not crazy revving mind you, just up to 4000 or so. After a couple of blips of this, the bike will take partial throttle or what ever I want to do with it. This bike wants the enricher after it sits for a few hours sometimes. There are alot of variables but I will take them over FI any day.

    Synching the carbs makes the most difference in off idle ridability, my bike is titz :smile:

    My Kawasaki never needs choke and takes gas perfectly, something the Honda cant do. Just a CH of throttle cracked and hit the starter button and it starts and idles immediately.
     
  9. flummerylove

    flummerylove New Member

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    washer and o-ring are indeed present. In previous posts I mentioned the o-ring might be suspect..perhaps flattened etc. Will replace. They are not hard. I did a surgical bench test on the carbs, syncing butters. Have not nanomtered them on the bike yet...but it runs better than it ever has (pullin hard throughout all revs and gears) with this last bench test so I am assuming I am very close to good sync. However that could be the issue and I will sync them on bike. Squirrelman said the bike shouldnt even run with mixture screws under 1 turn. Mine does run with them closed still. When they are closed, thats when I get the closest I possibly can to having the bike idle "right" with about 3/4 turn in on throttle stop screw. If I open mix screws to 2 turns out or 1.5 turns out, I have to turn in the throttle stop screw about 2 turns in to get it to idle around 800-900. Seems whatever mixture setting I do, she will not idle with butters closed, or even a bit open. Dont even want to admit how many times I have changed oil on this bitch because of gas fouling. My feeling is if I cant get her to idle soley on pilot circuit alone with no throttle stop screw added, I can just keep on changing that gas fouled oil every 3 days. This is the main issue with this bike that I cant seem to solve yet...even after a major overhaul...
     
  10. flummerylove

    flummerylove New Member

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    ...and she wont start with enrichment on with any of the above combos
     
  11. ridervfr

    ridervfr Member

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    What about your float needles being shot? Honda still sells them which I have, (No-I aint gona sell them) If you want gen-you-wine Honda parts regarding the pilot o-ring they sell an entire kit with the bowl gasket along with some other parts for me thinks ova $20.00 er so.

    The flooding and the erradic idle etc are two different problems me believes. You need to synchronize those carbies on dah bike, have fun burning the back of your hand. I have some double secrect super spy tools for easing the pain for this job. Let me know as I feel that a little pain is good for some people. :smile:
     
  12. tinkerinWstuff

    tinkerinWstuff Administrator Staff Member

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    sounds like sync is probably close enough to not be the cause of a problem. As ride mentioned; did you bench test the carbs for leaks? This includes making sure the float needles are seating.

    What size pilot jet is installed?

    Are you sure the idle air mixture screws are not damaged - thus allowing fuel to flow even though you have them bottomed out (closed) ?
     
  13. kennybobby

    kennybobby New Member

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    It's Flooding Carbs, not a rich mixture problem

    The fuel level is set too high, or the inlet needles are not shutting off the fuel flow. If you are getting fuel in your oil maybe you should have mentioned that early on--that's a whole different problem than just a rich idle mixture.

    The gas is overflowing and running out of the main needle jet, or the level is so high that it doesn't take much venturi pressure to pull fuel out that path. It's not coming out of the transfer ports, it's out of the main.

    That's why closing the mixture screws has no effect--you are dumping raw fuel into that thang.

    Could be bad tips on the inlet needles not shutting off. If the inlet needles are good then you need to adjust the float setting to lower the fuel in the bowls. You can use a clear tube on the drain port to actually see how high up the fuel is filling the bowl. Also can drain a bowl into a cup and measure how much is in there, then compare that amount to what it should be in a normally operating bike.
     
  14. tinkerinWstuff

    tinkerinWstuff Administrator Staff Member

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    The first carb you drain will drain the fuel rail as well and dump more fuel than each after
     
  15. squirrelman

    squirrelman Member

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    Yes, yes, yes to K-B's post #13 above.

    We know you've already inspected all the mixture screws and found sharp points on the ends, and all look similar, right ??

    It's obvious that if your bike idles with mixture screws fully closed, fuel is getting in from somewhere it should not.......like bubbling up from the top of the main jet holder tubes and around the slide needles cuz the fuel level is too high ( improperly set float levels or leaky float needles) so you need to fix that and reset mix screws to their proper setting, about 2 1/2 turns according to FSM and general practice.

    You'll know the problem is fixed when plugs stay clean and idle is even and mixture screws are open to factory specs.
     
    Last edited: Sep 7, 2011
  16. VT Viffer

    VT Viffer New Member

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    My first thought when looking at this thread was the float valves, too. Even the tiniest piece of crud will cause them to stay open and allow too much fuel in the bowls.
     
  17. OTTOMAN

    OTTOMAN New Member

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    For whatever reason I could not get logged in to contribute earlier but I believe you have a stuck float too...just went through this exact same thing on a riding lawnmower; no start, fuel contaminated crankcase oil and with the sparkplug removed I could actually see fuel flood the cylinder while cranking. Check/clean the needles & seats, find a specification for float height and adjust as needed.
     
  18. flummerylove

    flummerylove New Member

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    Stock 40 idle jet and 130 main. I am not sure the idle air mixture screws are not damaged. In my research the very tips of these are not pointed RIGHT!? maybe egg on face time.. keihin_tip.jpeg
     
  19. flummerylove

    flummerylove New Member

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    Yes used the clear tube method. Yes. Inlet needles are new. *variable* inlet needles are for a VT600. And having talked to honda peeps at stealerships (thinking I might trust their knowledge..WRONG) I bought the VT600 needles in lieu of OEM backorder needles at the time. They are virtually identical..mine are .63mm shorter than the OEM. soo compensate for that when setting floats or am I f**ked? How much fuel should a normal bike have in one bowl after draining the rail? I know clear tube method is not an accurate way to set floats on inclined carbs, but can anyone offer a clue as to approx where fuel level should be on outside of bowl, with clear tube, when floats are set to 9mm? That would help greatly as a quick reference. I have fussed with this problem bout 15x also...
     
    Last edited: Sep 9, 2011
  20. squirrelman

    squirrelman Member

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    Stock idle jets are #38, i believe.
     
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