Shovel Trouble

Discussion in 'Electrical' started by Ponytail Pat, Jun 27, 2009.

  1. Ponytail Pat

    Ponytail Pat Member

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    What kind of damage would a poorly ground condenser do to the electrical components and/or charging system? I have a recently re-build 1977 Shovelhead (kick start only), new battery, new coil/coil wires, voltage regulator rectifier, new points and condenser, and replaced the Keihin carburetor with a Bendix. It ran for 65 miles before it started cutting out and backfiring through the pipes upon excelleration. When I got it home, the condenser bracket was rattling loose. Now it will not start. I have re-timed it, checked the advanced flyweights, and installed a new condenser. Could my loose condenser have damaged my electrical or charging system?
     
  2. glider

    glider Veteran Member

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    Unlikely but not impossible that the condenser caused other problems. Usually a bad ground on the condenser as in loose will cause the points to burn up from arcing and poor running will result until it doesn't run any more.
     
  3. rj_harley

    rj_harley Member

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    Have you looked at your intake manifold? When a shovelhead backfires an intake manifold can come a little bit loose from the cylinders and the engine will take in false air. Result: The engine will not start anymore.
    What also can be the problem is that the regulator died.
    I've worked in a local harley shop for two years and we had a lot of older harley that had a broken regulator due to bad grounding of the electrical system.
     
  4. NEWHD74FAN

    NEWHD74FAN Experienced Member Retired Moderators

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    Condenser ground loose would only cause more pitting of the contact points and it assists in making the points opening and closing more "abrupt" which makes the ignition waveform sharp, magnetic field/coil performance better.

    Did you set the initial point gap around 0.016-0.19, then timing using the proper timing mark and reference point?

    What type of charging system is being used, if super old DC generator type with mechanical regulator that needs polarization perhaps?

    I would check the specific service manual, but here is a little background info...

    http://www.hdtalking.com/harley_davidson_engine_related_issues/3412-harley_ignitions.html
     
    Last edited: Jun 30, 2009
  5. Stoney61

    Stoney61 Member

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    Have you checked for spark? I would start there.... it sounds like it could be a defective coil.
     
  6. Ponytail Pat

    Ponytail Pat Member

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    New points, new condenser, new spark plugs, it started and ran for 4 miles before starting to sputter and backfire. Checked the intake manifold beforehand and it was tight.

    There is spark in my front sparkplug, my points are not excentric, but I have no fire in my front cylinder. Rear cylinder runs fine. Wassup?
     
    Last edited by a moderator: Jul 11, 2009
  7. glider

    glider Veteran Member

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    Have you checked the plug wires?
     
  8. Ponytail Pat

    Ponytail Pat Member

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    I have pulled the front sparkplug out and grounded it to the motor. I then manually opened the points and got good spark. I put the plug back in the cylinder and it won't fire, but the rear cylinder does. The plug wires are new and if I get spark outside the cylinder, why won't it spark inside?
     
  9. glider

    glider Veteran Member

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    Quite possible it is sparking in the cylinder and you have an intake leak or valve problem and that's why it isn't firing on that cylinder. Take a compression test and then check the intake connections. Also try switching the plugs and see if the problem migrates to the other cylinder.
     
  10. Ponytail Pat

    Ponytail Pat Member

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    What is the average psi on a compression test for a stock 74 cubic inch shovelhead? And what is the tolerable variance between the cylinders? My dry reading was front cylinder 90 psi and rear cyclinder was 110. My wet reading was 110 on the front and 130 on the rear.