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  1. #1

    Default carby bakefire

    Hi I have a S&S super e carby on my81 fx I have tuned it in as per the guide but it pops and backfires at around 50 mph when backed of or under load .
    Has this something to do with the carby or has it to do with timming . It also find it doesnt respond very well.

  2. #2
    Join Date
    Mar 2008
    Location
    New Jersey
    Posts
    71

    Default

    I am not a big fan of S&S carbs. More info needed. Is this a recent addition? If so did it run ok before? Is it a stock engine? Is it backfiring through the carb or out the exhaust? It sounds as though it is backfiring through the carb which usually indicates a lean condition and it may need a jet change. But before that is tried, a bubble test should be done on the manifold and connections to determine if there is leakage there. If no leakage at the plumbing connections, at 50 MPH it should be operating on the low speed circuit and may need fattening up.

  3. #3
    Join Date
    Jun 2001
    Location
    Central Illinois, USA
    Posts
    4,081

    Default

    As Lyle said!

    http://virtualindian.org/11techleaktest.html

    O-ring assemblies should be tested while assembled to prevent over-tightening.

    Please remember the clamps do not secure the carburetor upon the machine;
    The carb support does.

    .....Cotten
    AMCA #776
    Dumpster Diver's Motto: Seek,... and Ye Shall Find!

  4. #4

    Default

    Hydraulic or solid lifters? color of spark plugs? stroked/ cam change? new condition or was running OK before? drag pipes? High speed backfire through "carby" would indicates larger main jet needed, tuning per guide addresses needs for larger jets.

  5. #5

    Default

    This is a stoke ariginal engine .when I bought it it came with the S&S on it I have done a leak test on Manifold it was all okay both plugs are not oily or lean looking nice colour to them and it only backfires though the carby when under load or when just twisting the throttle .

  6. #6

    Default

    Check accelerator pump? Timing?

  7. #7
    Join Date
    Nov 2018
    Posts
    130

    Default

    I have always found the S&S Super E to be a good carby. If it is tuned as per the instructions, good o rings(or bands) and support fitted, they run well.

    One thing I have come across many times is the electronic module breaking down. I have replaced every one I have come across. They typically show some potting material leaking out of the enclosure. This will give you some strange effects.
    If you are still using the original springs in the advance and retard, they loose some tension after time. The spring anchors also seem to bend inwards sometimes.

    Even if the timing is in good condition, I like to change it out for a later electronic system. Can be set up as single fire if preffered with a new coil, and is very tunable. My personal favorite is the Crane HI4, before S&S brought them from Crane.

  8. #8

    Default

    Ok I forgot, points and condensers went away in mid year 1978. That being said I have had the same electronic ignition in a 1992 FLHS with the same Shorty E that gave me fits with its missing/popping/dead throttle until I changed the coil. I tried all the usual fixes that have been mentioned, none cured the matter, until the coil was replaced.

  9. #9
    Join Date
    Jun 2019
    Posts
    8

    Default

    Quote Originally Posted by aumick10 View Post
    I have always found the S&S Super E to be a good carby. If it is tuned as per the instructions, good o rings(or bands) and support fitted, they run well.

    One thing I have come across many times is the electronic module breaking down. I have replaced every one I have come across. They typically show some potting material leaking out of the enclosure. This will give you some strange effects.
    If you are still using the original springs in the advance and retard, they loose some tension after time. The spring anchors also seem to bend inwards sometimes.

    Even if the timing is in good condition, I like to change it out for a later electronic system. Can be set up as single fire if preffered with a new coil, and is very tunable. My personal favorite is the Crane HI4, before S&S brought them from Crane.
    Have to disagree with crane hI4. And i have one in one of my bikes...not a great one and they failed a lot.Altima / dyna and a few others have so many better ones out now. The super E works just fine....but i rebuild a few beginning of year if guys dont treat the gas.....makes a mess and fart and backfire lean when not rite

  10. #10
    Join Date
    Nov 2018
    Posts
    130

    Default

    My experience is the opposite. I have three HI4's in my evo bikes and no problems so far, although I don't do high miles anymore.
    The dyna's we used to run in our drag bikes alawys shook themselves to failure. Don't have much experience with Dyna's in road bikes.

    I have recently had to clean out my E from sitting around with gas in it, although this will happen to any carby today. I have changed all my bikes over to Ethanol free gas, as they sit around too much.

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