need help 04 883 backfiring

Discussion in 'Sportster Models' started by barnone, Mar 16, 2014.

  1. barnone

    barnone Member

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    my 04 883 is backfiring idols fine go to give it gas stalls and backfires. thinking it could be crank position sensor anyone know a we to test one?

    anyone know a way to test a crank position sensor
     
    Last edited by a moderator: Mar 16, 2014
  2. fin_676

    fin_676 Experienced Member Staff Member Moderator Contributor

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    It could be an indication of a very lean mixture so perhaps a look at the carb may be a good starting point especially if this problem is after a winter lay up
    So a wee bit more info may be required ie last time it ran ok, any recent work done on the bike etc etc

    Brian
     
  3. Jack Klarich

    Jack Klarich Expert Member

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    Check intake for leaks and have a look at the plugs and wires first Harley Davidson Forums Have a look here
     
  4. barnone

    barnone Member

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    ran fine for about ten miles. got on highway died. trailer home. put new plugs in took off tank emptied gas new gas cfoam took carb off cleaned slow flow jet clogged put back together still no start. took off petcock ran straight gas line started right up, shut down got new petcock started right up but only at idle, rev up backfires and dies. screamin eagle air flow stage one kit with pipes wires and plugs. thanks brothers
     
  5. stray dog

    stray dog Junior Member

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    I would be checking the float, needle & seat.
    Sounds like a carb cleaning and rebuild kit is in order.

    The seafoam sitting in there may help some after a day.

    Hopefully Brian will check back in here to confirm (good carburator guy).
     
  6. barnone

    barnone Member

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    thanks stray dog, im thinking carb to but my guy took it apart and cleaned, but maybe we missed something
     
  7. fin_676

    fin_676 Experienced Member Staff Member Moderator Contributor

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    I think a good and proper rebuild of the carb is in order as it does sound like you are experiencing very lean ie plenty of air and not enough fuel could be a blockage some place
    first thing to check is the operation of the accelerator pump = take off the air filter snap open the throttle and you should see a squirt of fuel shoot down the throat of the carb
    However as carb is now 10 years old may be time for a rebuild and good clean up
    Also you need to check the vacuum pipes from the back of the carb to the voes and the petcock
    If you have changed the petcock for a non vacuum one if you did not seal the pipe then the voes will not advance the timing a self tapping screw in the loose end of the vacuum pipe will block it

    Brian
     
  8. barnone

    barnone Member

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    thanks Brian the bike is ten years old, but only 6600 miles, but I think you are right its still carb related its going in the shop later this week hopefully they can figure it out, keep you posted thanks and I put the petcock back on with vacuum
     
  9. fin_676

    fin_676 Experienced Member Staff Member Moderator Contributor

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    Modern fuels have stuff added that is not good for plastic and rubber parts inside carbs so even though the mileage is low the ethanol may have damaged some seals and parts
    Another thought is that of carb icing which does occur here in the UK at this time of year as the air flowing through the carb chills as it is compressed in the throat of the carb fuel vaporisation causes further chilling the metal that the jets are made of is a very good conductor of temperature and get very cold the moisture in the air will freeze on the jets and usually blocks the slow jet which results in a weak mixture and backfiring
    Although I have never had the problem on my 883 sportster but on the big twins it was a regular occurrence till I replaced the carbs

    Brian
     
  10. DFHarley19

    DFHarley19 Active Member

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    I am not sure but... Is it fuel filter?