05 1200C Chokes and Dies When Hot

Discussion in 'Sportster Models' started by ms99, Jul 17, 2010.

  1. ms99

    ms99 Member

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    Bike has SE airbox, SE-II slipon mufflers, and Thunderjet kit in the carb. I bought it new and did the all the work with a long time Harley riding friend supervising.

    This spring before the first ride I changed the oil, tranny fluid, plugs and replaced the battery. Plugs were a bit gunked up so I leaned the mixture down a little.

    It has been running great for several years, but last summer it started acting up on me. At speed (on the autobahn :D ) it runs fine. Riding around it is fine. But at low speed ~ 30-mph or when I try to ride away from a stop or accelerate from slowing down, the bike chokes real bad and sometimes dies:(. It will idle OK, but pulling away it chokes and stutters real bad. This only happens when the bike is warmed up and running around 130 degrees or hotter on the HG oil temp dipstick - gauge.

    It is still acting up after the spring clean up.

    I've read just about everything I can in the self-help section and other Sporty postings; and found a couple things I plan on checking - leaking around intake manifold, vaccum lines, etc. Another friend has loaned me an Edlebrock carb to try. But I haven't started that project yet.

    But I am curious if anyone has run into anything that sounds similar or has any other recommendations to look at?


    Thanks in advance.


    Mike
     
  2. Iceman24

    Iceman24 Well-Known Member

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    I was thinking something's gunked up in the carb - have you cleaned it lately? Might be a good time to try the loaner carb & see if it does the trick??? I'm sure there are more seasoned mech's ready to advise, but sometimes all it takes is a small bit of debris to wreak havoc in your fuel system. Good luck!
     
  3. glider

    glider Veteran Member

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    You mention"Thunderjet kit in the carb"??

    The thunder jst is the unit that supplies additional fuel from the float bowl to the intake tract of the carb.

    Could you be referring to a dyno jet kit with the different jets and metering rod and NOT the thunder jet?

    It sounds as if it isn't jetted correctly and the low speed jet is too big. What size did you use in the jet selection?


    This is a thunder jet kit.

    [​IMG]
     
  4. ms99

    ms99 Member

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    Sorry Glider - you are correct it was the Dyno Jet kit in the carb.

    This is my first HD and I am not much of mechanic. I'll do most basic simple stuff -oil, fluid, plugs, etc. Most other problems get away from me quick.

    I used the 175 main jet and set the mixture per the DJ instructions.

    I have not cleaned the carb since I put the jet kit in.

    Is the 'Fortron' something you just dump into a tank of gas and run it thru?

    Or would it do to use some sort of spray carb cleaner?

    Thanks for the quick responses.
     
  5. ms99

    ms99 Member

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    Jayson - How does one check the CPS?
     
  6. glider

    glider Veteran Member

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    Mike

    You aren't the first poster to post like you have using the DJ kit and having problems. I have seen this happen before and the outcome was to put the carb back to stock and just rejet it with the proper size jets from HD.

    *Twin Cam CV Carb Rejet Suggestions - Harley Davidson Community

    The markings on the DJ kits don't coincide with the HD numbers on the jets and usually the DJ kit will knock the heck out of gas mileage because they run too rich. Your problem seems to be of a different nature being it happens after a run and upon acceleration, it chokes up. This may be a number of things causing it not just improper jetting. What size jets did you use in the low and high speed jetting and did you use the DJ needled in your carb?
     
  7. ms99

    ms99 Member

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    The main jet I used was the one DJ recommended with my change of mufflers and airbox. And yes I did put the DJ needle and drilled out the slide lift hole per their instructions (www_dynojet_com/pdf/8135.pdf - post count won't let me post links yet.)

    The friend who loaned me the Edlebrock carb now has a Mikuni carb on his bike (04 XL1200C) and I was thinking of getting their Sportster/Buell HSR42 if the carb turns out to be the problem. Opinions?

    However, Glider it sounds like you recommend sticking with the stock carb rejetted?
     
  8. glider

    glider Veteran Member

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    However, Glider it sounds like you recommend sticking with the stock carb rejetted?


    ABSOLUTELY!!!

    And I don't advocate the DJ kits or even the drilling of the slide either. It can cause some drivability issues in cooler weather when the throttle is opened suddenly. It raises the slide too fast and leans out the mixture. A lighter slide spring sometimes helps on some bikes but the drilling isn't a good idea.

    What size jet did the DJ kit suggest in the low jet and main jet positions?
     
  9. ms99

    ms99 Member

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    Per the instructions I used main DJ 175 jet along with their needle. I don't recall seeing any other jet with the kit.

    I also used the DJ emulsion tube.

    Is it possible to order just the slide for the carburetor?
     
  10. glider

    glider Veteran Member

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    Should be a low speed jet too. (42.45.46)?

    Like mentioned above the DJ jets don't correspond to the HD jets as far as sizing.

    This is where the problem is.