twin cam problems?

Discussion in 'FXR Models' started by joehartwig1967, Apr 15, 2010.

  1. joehartwig1967

    joehartwig1967 Member

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    I put a twin cam in my 1990 fxrs. used an 04 sportster wiring harness, o4 flt screamin eagle ignition module , custom chrome #605050 coil. The motor is a 2000 screamin eagle with 45 hrs mikuni. Bike will fire run for a second and die, Will not fire again until I quit cranking the starter, then will do the same. Tssm has been bypassed. Seems to be firing on rear cylinder even though front cylinder has spark.
     
  2. maine-e-axe

    maine-e-axe Junior Member

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    I would say a circuit breaker somewhere isn't big enough.
     
  3. joehartwig1967

    joehartwig1967 Member

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    there are no circuit breakers, just 15 amp fuses.
     
  4. Hoople

    Hoople Account Removed

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    Joe, I don't understand what the above statement means..

    If you were to remove both plugs, hook up both coil leads to the plugs, ground the body of both plugs to engine and crank engine.. do you see repeated firing on each plug? And even for the fraction of a second after you release the cranking button and the engine is spinning down to 0 rpm, do you see a couple of firings? How is the ignition module triggered. Is it self contained with its own trigger circuit (photo, hall effect, reluctance etc)?
     
  5. joehartwig1967

    joehartwig1967 Member

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    I have both cylinders firing now had a short in the plug wire. but still have the problem of it running for a second then dies wont fire again until i release the starter button and push it again. it starts immediatly barely a full rotation of the crank. the module is self contained
     
  6. hogrotten

    hogrotten Junior Member

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    So it's only running when you first crank it off basicaly right? If this is the case I've had this happen on old chevys before. Check to see if you have power to the ignition module only when the key is on and not cranking the bike. Sounds like the power is flowing through the selenoid wiring when cranking but now steady power to the coil and or the ignition module. Get a wiring schematic and make shure you got power to the module when the key is on. Good luck.:s
     
  7. joehartwig1967

    joehartwig1967 Member

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    Yep already been there and done that . I have the service manuals for the fx, sportster and the fl.
     
  8. Jack Klarich

    Jack Klarich Expert Member

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    Change the ignition system, something wrong in there, probably the module
     
  9. joehartwig1967

    joehartwig1967 Member

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    the module is new, but that doesn't mean anything. I can have the dealer test it.
     
  10. stev36mc

    stev36mc Member

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    I dont get it. What year is your Twin Cam motor? What ignition system are you using? I have a Twin Cam motor in my FXR and as you know ignition is triggered from the crankshaft sensor. I am using a Thunderheart Stand Alone single fire ignition. Works fine.