Coughing thru the carborator

Discussion in 'Softail Models' started by PJLittle, Jan 4, 2009.

  1. PJLittle

    PJLittle Member

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    I have a 2006 Heritage Softail, I have Vance and Hines drag pipes, I had bigger jets put in the carborator and a thunder max box put on it. Now it coughs. I have taken it to all the Harley Davidson Dealerships in my area, they say that they fixed it, but it still coughs. I have taken it to a couple of no name shops and they say that it is supposed to do that... I took it to the representative of Thundermax and he said he fixed it but it isn't fixed. I have never had this problem until I put the Thunder Max in and I only get a 140 miles per tank.

    Do you have any suggestions?

    Thanks!
     
  2. glider

    glider Veteran Member

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    My own feeling is that the T Max is still relatively new and still needs some attention to detail before it's perfected.

    As far as the cough, it's not normal and also not a good thing. It can damage intake seals and other parts if it continues. Set up properly a cv carb will rarely if ever cough back.

    Mostly all coughing is the result of improper jetting or a problem with the accelerator pump/circuit or the linkage or nozzle for it.

    Some recommendations for jetting on your bike would be a 45/46 low jet and about a 180/185 high speed jet and the needle in the carb raised up with 2 - #4 washers under the head to bring on the fuel curve a bit sooner. Done correctly the CV carb gives good MPG and performance but you have to find out what jetting was installed and what else was done by the dealers before you can continue further. Drop the float bowl and have a look.

    You may also have an intake leak causing it to lean out.

    Read these posts.

    *Twin Cam CV Carb Rejet Suggestions - Harley Davidson Community

    Finding An Intake Leak - Harley Davidson Community
     
  3. STEVE07

    STEVE07 Well-Known Member Staff Member Super Moderators

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    I'm probably wrong ,but I go back to a V8 if the carb. is coughing your valve timing is out
     
  4. PJLittle

    PJLittle Member

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    Thanks, it was a recall on my jets and carborator and Harley Davidson replaced them and I think my problem is the T Max because I didn't have the cough until I had the T Max installed. All summer I tried to get it fixed but it is still coughing...

    Do you suggest I take the T Max out?

    Thanks
     
  5. glider

    glider Veteran Member

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    Your choice there but I would call them first, I think they had a similar problem and if I recall they had an upgrade to it available to fix the problem.

    Chances are you could have the stock size jets if they replaced your carb.
     
  6. krikket

    krikket Active Member

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    You're partially correct. Mostly, if the ignition timing is too far advanced it will backfire through the carb. If the valve timing is off, it may backfire through the carb but you'll have a large list of other symptoms as well.
     
  7. scootertrash

    scootertrash Account Removed

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    Take the thunder junk off, have your harley shop remap it to the VH pipes and ride on!
     
  8. glider

    glider Veteran Member

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    You're right, that got right by me too.!

    Let's see what this poster replies first before we make him go poof .:D

    Sure they do!:bigsmiley20:

    And a "recall" on the jets???

    Dave?
     
  9. STEVE07

    STEVE07 Well-Known Member Staff Member Super Moderators

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    Last edited: Jan 6, 2009
  10. STEVE07

    STEVE07 Well-Known Member Staff Member Super Moderators

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    Fair enough. I'll behave myself:worthy