2014 Harley-Davidson Sportster Engine Misfire

  • Information herein pertains to 2014 Harley-Davidson Sportster motorcycles that start but run irregularly or misses on XL 883 SuperLow, XL 883R Roadster, XL 1200X Forty-Eight, XL 883N Iron, XR 1200 X, XL 1200V Seventy-Two, XL 1200CP Custom, XL 1200C Custom, XL 1200CA Custom Limited A and XL 1200CB Custom Limited B models.
  • Additional information available in the download factory service manual.

Harley Sportster engine misfire refers to a condition when the internal-combustion engine undergo failure of the fuel to ignite correctly or at all. When the Sportster’s engine misfires or misses,  it means the gasoline inside one or more cylinders begin to burn at the wrong moment or never ignite. Engine misfire can make the motorcycle engine run irregular, cause slow acceleration, rough idle and excessive vibration. The 2014 Harley-Davidson Sportster motorcycle general troubleshooting guide list possible causes and actions needed to fix a Sportster that starts but runs irregularly or misses.

Starts But Runs Irregularly or Misses

  1. Spark plugs are a device for delivering electric current so as to ignite fuel in each cylinder of a gasoline-powered internal combustion engine. Spark plugs that are in bad condition will fail to ignite the air-fuel mixture. Check spark plugs for improper gap, insulator damage or if they are partially fouled.
  2. Spark plug wires or ignition cables are wires that transfer spark from the coil to the plugs. Common signs of failing spark plugs are engine misfires. Spark plug wires that are damaged or in bad condition, shorting or leaking will fail to to ignite the fuel correctly, which can cause the Sportster to run unevenly. Replace wires if necessary.
  3. Inspect ignition system/charging system for a damaged wire or a loose wire connection at the ECM connector, ignition coil or wire connection at battery terminal.
  4. An ignition system malfunction will cause an engine to run erratically and misfire. Check for possible sensor failure.
  5. Faulty ignition coil. An ignition coil supplies high voltage to the spark plugs. A bad ignition coil, ECM, or sensor (TMAP, ET, HO2S or CKP) will result in engine misfire, loss of power and rough idle. A bad ignition coil will often trigger a check engine light to illuminate. Replace ignition coil if needed.
  6. If the fuel tank filler cap vent is clogged or a fuel line is pinched closed, it will restrict fuel flow. This will offset air-fuel mixture and cause the engine to hesitate upon acceleration. Inspect the fuel tank filler cap vent for blockage or crushed fuel line.
  7. Battery almost discharged. Low battery voltage can use to fuel pump to operate slowly triggering the fuel pressure to drop and cause a lean fuel condition.
  8. Intermittent short circuit due to a frayed wire insulation. Check for damaged wire insulation and fix if necessary.
  9. Contaminated fuel such as dirt or water in the fuel system will cause a Harley Sportster to run irregular or generate misses.
  10. Air leaks at the air cleaner or intake manifold can cause “lean misfire” as a result of air/fuel mixture being too lean. In other words, there is not enough gasoline in the mixture to burn.
  11. Partially clogged fuel injectors. A fuel injector’s responsibility to to spark liquid fuel intermittently into the cylinder of an internal-combustion engine. Partial obstructed fuel injectors will send vibrations through the motorcycle as though it is sputtering.
  12. Damaged exhaust or intake valve(s). A bent or broken intake or exhaust valve will cause a Harley-Davidson engine to have a misfire. It can also trigger a popping sound in the intake. Replace bent or broken valves if needed.
  13. Worn or damaged valve springs. If a valve cannot close before the next combustion cycle, the cylinder will lose compression and result in a misfire, which is termed valve float.
  14. Incorrect valve timing. Adjust valve clearances based on factory recommendations in the factory service manual.

This troubleshooting guide is a meant to help you trace and correct faults within the 2014 Harley Sportster mechanical and electronic system and provide a course of action needed to diagnose the problem and resolve it. Always refer to the factory service manual before attempting to work on your motorcycle. Improper service, repair or maintenance can result in serious injury or even death. 

Darren Gilbert

Hi I'm Darren, motorcycle technician, race and maintenance mechanic with 30+ years of experience working on choppers and street bikes. If my article does not answer your question, just submit a question in the comment box below and I will answer it ASAP.

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