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Thread: 09 Buell Blast running issue

  1. #1
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    09 Buell Blast running issue

    Hello fellow Buell enthusiasts. I was wondering if anyone could shed some light on my blast issues. Recently I had the Harley dealership pick up my bike and do a full diagnostic on it, as the bike was having issues starting and running. They claimed the battery was the issue, a fact that I had contested. Nevertheless, they put in a new battery and brought the bike back. The bike started right up, but as soon as I gave it some throttle, it would begin to choke and stall. I could technically leave it in idle without issue, but as soon as I apply more throttle to start moving, it chokes out and dies. Furthermore, right before it chokes and dies, it sounds like its backfiring through the carb. The stealership isn't too happy to be servicing the bike again and so I am pretty much on my own. One thing I did do, was take the carb apart and saw the fuel bowl gasket needed to be replaced, as it had warped and was not sitting properly in place. While this is an issue, it still doesn't explain what is happening. Any ideas would be quite welcome, thank you for reading this.

    David

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    Sounds like a clogged main jet. Watch this and you will see how to inspect that and various other parts. Also check for intake leaks. If this is a bit over your head, I’d recommend just taking it to regular independent motorcycle mechanic (not necessarily a Harley shop). It’s a carbed single... not too much to go wrong with it.

    https://youtu.be/_YbDLFoXtLI

  3. #3
    Senior Member Cooter's Avatar
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    I totally agree with 34:19.
    If it's popping through the carb when you give it gas off idle, it's going lean.

    When you give it gas off idle it is transferring from the idle circuit (that's fine because it idles) to the main circuit (jet and needle) and going lean because gas can't get through it... the jet is clogged and a common problem.

    IIRC a 170 is stock but you can go up to a 175 if you added a muffler or did intake mods. The jet size is the decimal equivalent of the drill size, so If you have a 170 drill you can clean it or open it up to 173-175 yourself. It's $6 new from HD and the same as an old Sportster.

    Take off the float bowl again and the big brass thing in-between the floats, in the middle, is the main jet. A 5/16" driver and the whole assembly will pull out. The jet itself is a flat head on the end of that assembly. Clean all the little holes. Re-assemble. Boom.

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    Also, check to make sure the slide is opening when you open the throttle.

    If it’s not, do this check...

    https://youtu.be/lfQz4cxezAk


    And be sure to put the jet holder back in the correct way if you get that deep into the carb.
    Last edited by 34nineteen; 11-17-2019 at 07:40 AM.

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    34nineteen and Cooter, thank you guys so much for the advice. I will be taking the carb apart again today and checking the idle and main jet for blockage along with ordering the carb bowl gasket since it needs replacing. If I may ask a question, when people mention an issue with "das boot," are they referring to the rubber fittings that connect the carb to the block? I feel like if it isn't an issue with the clogged jets, then it's an air intake issue or perhaps a control ignition module that is going bad. I know the module was an issue on the 2001 model, but I could have sworn the control ignition module is not lighting up the way it should, perhaps it is failing. Anyway, I will battle one thing at a time, starting with cleaning the jets. Also, I appreciate the two videos, I watched them both, and have learned an interesting little trick to check if the slide is functioning properly (properly pressurized) thank you!

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    Make sure your needle jet is in the correct orientation. One end is concave, the other is flat. Flat end down, concave end should extend into the air stream. If it's upside down, it won't pull fuel up no matter what size jet you have in it.

    Also, check the rubber diaphragm on top of the slide. If it has a tear or bad seal anywhere, it will not lift, which can cause your symptom.
    Last edited by jetlee; 11-18-2019 at 04:13 PM.

  7. #7
    Senior Member lunaticfringe's Avatar
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    Quote Originally Posted by Cooter View Post
    I totally agree with 34:19.
    If it's popping through the carb when you give it gas off idle, it's going lean.

    When you give it gas off idle it is transferring from the idle circuit (that's fine because it idles) to the main circuit (jet and needle) and going lean because gas can't get through it... the jet is clogged and a common problem.

    IIRC a 170 is stock but you can go up to a 175 if you added a muffler or did intake mods. The jet size is the decimal equivalent of the drill size, so If you have a 170 drill you can clean it or open it up to 173-175 yourself. It's $6 new from HD and the same as an old Sportster.

    Take off the float bowl again and the big brass thing in-between the floats, in the middle, is the main jet. A 5/16" driver and the whole assembly will pull out. The jet itself is a flat head on the end of that assembly. Clean all the little holes. Re-assemble. Boom.
    When you give it gas off idle it is transferring from the idle circuit (that's fine because it idles) to the main circuit (jet and needle) and going lean because gas can't get through it

    i know you mean well but that is incorrect. whether it's a CV style or VM style carb....the progression of fuel metering steps is from idle circuitry----to intermediate circuitry----to main jet/needle circuitry. the intermediate circuitry is controlled by the pilot jet. simply do what Lee mentioned and plan on, at the very least, purchasing a replacement pilot jet. i stock them if and when you obtain the correct size/number needed. a few bucks each.

  8. #8
    Member Endopotential's Avatar
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    I learned a lot about tinkering on carb'd bikes with my old Suzuki GS500.

    Not sure how much of this applies to the Blast, but figure some basic principles should still work.
    https://joshkarnes.blogspot.com/2017...or-issues.html

    One good take away - resist the temptation to spray carb cleaner on rubber parts like gaskets, washers and the diaphragm - the solvent can eat away at them.

  9. #9
    Senior Member Cooter's Avatar
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    Quote Originally Posted by lunaticfringe View Post
    [COLOR="#800000"]
    i know you mean well but that is incorrect.
    Read his symptoms before you post snarky pointless babble. Are you mad you can't sell him a Blast fuel pump? LOL.
    If the pilot in the transition circuit was clogged it would stumble but still rev up once the diaphragm lifted the needle out of the main jet. Since it stumbles and dies, The main jet is probably clogged. Heck these carbs don't even have an accelerator pump.

    OP: To get running: Clean the main jet. The big one. The one in the middle of the floats. Yes, you should remove the other jet while you're in there, in fact, you should re-build the whole carb and replace all the jets (if you're up for that).

    Jetlee is correct about the needle jet, but you'd know if the carb was totally apart right before it wouldn't run correctly... and would have hopefully mentioned that. JL is also correct about the diaphragm (that controls the needle, that goes in the main jet you need to clean). If the slide doesn't move when you gas it, replace the diaphragm. It comes in the re-build kit I mentioned above.

    "Das-boot" is indeed referring to the rubber boot between the carb and the cylinder head. Usually not a problem with a stock air cleaner assembly, is yours stock? Easy to check by spraying carb cleaner at it while idling (high vacuum) and listening for an idle change.

    Good luck and report back what you find!

  10. #10
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    Quote Originally Posted by Endopotential View Post
    I learned a lot about tinkering on carb'd bikes with my old Suzuki GS500.

    Not sure how much of this applies to the Blast, but figure some basic principles should still work.
    https://joshkarnes.blogspot.com/2017...or-issues.html

    One good take away - resist the temptation to spray carb cleaner on rubber parts like gaskets, washers and the diaphragm - the solvent can eat away at them.
    Informative article!



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