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  1. #11
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    I'll try the voltage tests again. Maybe I was doing something funky. I can also try a different multimeter.

    The plugs were looking great when we had it running at its best. No carbon buildup, not gray either. When we did the swap to the 85 to test whether we were correct in thinking we were starving for fuel - the plugs predictably got more gray and lean looking. The plugs were checked after killing engine at speed/under load a couple times, but more recently just after idle/rev in the garage.

  2. #12
    Super Moderator CXPHREAK's Avatar
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    A weak spark will often cause black plugs from poor combustion. I think the spark may be OK.

    Are you sure you don't have any vacuum leaks?

    What actually were the 8/9 numbers from your stator test? If the motor has been fitted with an aftermarket stator the resistances won't match Hondas chart.
    Rebuilding Handlebar Switches

    Rider 81 500C, Thingy Born a 78Z. Ozdeluxe born an 80 shadow.

    GET A MULTIMETER RTFM I am a CX500. If you maintain me I will run forever.

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  3. #13
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    I honestly have no idea whether this is an aftermarket stator. other than the few rebuild kits etc that we have done here - any changes would have been long before my friend owned the bike.

    My thought was that the spark was good too. Just trying to be sure. The #8/9 measurement was 79, which was just in the range of 77-95. I just checked again and it read 78.8. #5/9 is still 301.

    Vacuum leaks: I am honestly not sure of anything anymore Seriously though, I believe that we have checked all the usual suspects (at least that we know about). We did replace the right inlet manifold with new o-ring from David Silver spares. We replaced both air cut diaphragms and tiny o-rings (full air cut-off rebuild kits). We have not done a spray test around the carb/manifold/boots connections in a while to see if any new leaks have popped up.

    Are there any specific tests you would suggest to find vacuum leaks?

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  5. #14
    Super Moderator CXPHREAK's Avatar
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    Definitely a factory stator with a low 5/9.

    Your bike is behaving as though there is an initial mismatch of mixture on opening the throttle. Something CV carbs were especially designed to prevent.

    It also reminds me of a lean mixture. Like blipping a cold motor.
    Rebuilding Handlebar Switches

    Rider 81 500C, Thingy Born a 78Z. Ozdeluxe born an 80 shadow.

    GET A MULTIMETER RTFM I am a CX500. If you maintain me I will run forever.

    http://cx500forum.com/mediawiki/index.php?title=Main_Page

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  6. #15
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    Quote Originally Posted by CXPHREAK View Post
    Definitely a factory stator with a low 5/9.
    Does this seem low enough to need replacing??? Or do you think this is not the cause of our issues here?

    Any idea what would cause this mismatch? Would it be something as simple as a different jet size? Or are we talking about a clog still somewhere in the early stages of fuel delivery? We know the press-in idle jets are clear. We know the passage from the air cut-off is clear. We HOPE the tiny holes behind the butterfly are clear all the way through from idle jet to carb throat - but I am not sure if there is a way to confirm this. The passages definitely take some turns that prevent running a copper strand through there. Soaking, carb spray, air and steam seem the best/only way to really get to those areas.

    Do you guys feel air come through the tiny holes if shot into the idle jet tower? I can't recall whether I really felt that.

  7. #16
    Super Moderator CXPHREAK's Avatar
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    I can definitely feel the air come through the three venturi holes when I put the air gun to either the idle jet or mix screw end. But I can't tell how many holes I'm feeling. The first hole looking down the throat is obvious as you can see through it with the mix screw removed.

    Similar to Larrys book I block the drilling to the ACV and fit and seat the mix screw and spray aerosol carb cleaner into the idle jet tower using an old passage plug on the spray tube to maintain pressure. Then you can check flow into the venturi visually.

    A hillbilly method I use that's not in Larrys book {Larry would have more decorum} is to clamp my garden hose to the mix screw tower and turn on the tap. This is good for checking. as well as blowing out crap loosened by solvents, ultrasonics, CLR etc.

    The stator reading is below spec but not badly. It may get worse slowly or quickly. Perhaps Nostradamus wrote a quatrain on CX stators.?
    Last edited by CXPHREAK; 12-13-2016 at 05:32 AM.
    Rebuilding Handlebar Switches

    Rider 81 500C, Thingy Born a 78Z. Ozdeluxe born an 80 shadow.

    GET A MULTIMETER RTFM I am a CX500. If you maintain me I will run forever.

    http://cx500forum.com/mediawiki/index.php?title=Main_Page

    The WIKI link for all the good tech stuff. including free FSM's with addendums

  8. #17
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    Quote Originally Posted by CXPHREAK View Post
    I block the drilling to the ACV and fit and seat the mix screw and spray aerosol carb cleaner into the idle jet tower using an old passage plug on the spray tube to maintain pressure. Then you can check flow into the venturi visually.
    I'm going to give this a try. It just seems like the best area to address to me - since the improvements that we have had were all based on getting the small passages, idle jet area even cleaner than we thought we already had them.

    Last questions for today... How do you block the ACV? Just with your hand? Or is there a special trick (I don't have Larry's book unfortunately)? Also, I have not tried CLR yet. Perhaps a bit in the idle jet tower for good measure???

    I'll report back.

  9. #18
    Super Moderator CXPHREAK's Avatar
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    When you spray you will see which hole in the ACV area needs blocking. I have a rubber cone of unknown origin.
    Rebuilding Handlebar Switches

    Rider 81 500C, Thingy Born a 78Z. Ozdeluxe born an 80 shadow.

    GET A MULTIMETER RTFM I am a CX500. If you maintain me I will run forever.

    http://cx500forum.com/mediawiki/index.php?title=Main_Page

    The WIKI link for all the good tech stuff. including free FSM's with addendums

  10. #19
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    I have run the drill through that passage - so I think I know the one. Thanks for the rubber plug tip.

  11. #20
    Administrator ChopperCharles's Avatar
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    If you're running pods, you're never going to know for sure if you have a correct baseline. The first thing to do is reinstall that airbox and filter, at least temporarily. Get the bike running correctly with that setup, then play with modifications. These CV carbs don't love pod filters, but it is possible to get the bike to run decently on them. But you have to know where you're starting at first. That said, if you really want to run naked carbies, I suggest Murray's kits. They're pricey, but they're a one-stop, runs-like-a-top fix.

    Charles.
    Visit my Blog: Modified Motorcycles By ChopperCharles at http://choppercharles.com

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