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Cause of spark plug failure - XL 1200 C Sportster Custom Harley Davidson Motorcycles

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Hi Chriscrowley, and the usual suspects are:
1. Plugs in bad condition or partially fouled.
2. Spark plug cables in bad condition or leaking.
3. Spark plug gap to close or to wide.
4. Faulty ignition coil, module and or sensor.
5. Battery nearly discarged.
6. Damaged wire or loose connections at battery terminals,
ignition coil, or plug between ignition sensor and module.
7. Intermittent short circuit due to damaged wire insulation.
8. If your bike has a CKP sensor you must leave both plugs in
head and check for spark with a 3rd plug. Good luck.

Posted on Jun 07, 2015


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What would cause a coil to burn out on a Mazda Tribute 05 v6

Ignition coils fail due to bad spark plugs or plug wires. Another potential cause is heat and vibration, which can damage the ignition coil's windings and insulation. If an engine is experiencing repeated coil failures, the underlying cause may be resistance from worn spark plugs or excessive spark plug gap. And in rare cases, the failure may be due to a lean fuel condition caused by leaky valves.

With coil on plug (COP) type coils, the rubber insulation dries up (over time and heat from the engine) and cracks and will arc across the engine's metal- shorting out. (Electricity seeks the path of least resistance)

By design, coils take low voltage energy from the battery (12-Volts dc) and transform that energy into a very high voltage charge (in the range of 30,000 to 35,000 volts) to energize the spark plugs which in turn ignites the fuel.

If a spark plug or plug wire is open or has excessive resistance, the ignition coil's output voltage can shoot higher (above the max threshold of 35,000 volts) and burns through the coil's internal insulation, causing a short.

When a coil failure occurs, the coil's voltage output drops, and the engine may not start or may misfire badly when under load.

Extreme caution should be exercised when handling coil packs that are energized- a lethal dose of voltage can arc across the air into the body. So don't touch them when the engine is running!

As stated earlier, if you need to replace the COP, replace the spark plug too, make sure the spark plug is properly gapped.

You can read more about coils here:

Ignition Coil High Voltage Display

Feb 05, 2017 | 2005 Mazda Tribute

2 Answers

99 Dodge Durango 5.9l V8 turning over but not starting. Strong smell of gas from air intake. Plugs sound like sparking. Fluids good and clean air filter. Any ideas?

Cam Sensor Failure Causing no Start or Stalling : Dodge ... > Problems > Dodge > Durango
Dodge Durango Cam Sensor Failure Causing no Start or Stalling. ... On the 4.7L V8engine, the Camshaft position sensor failure can cause the engine to crank but not start or it can ... On the 5.9L V8 engine, rerouting the ignition coil wire and spark plug wires can help solv. ... 1999 Dodge Durango ... Drove good till put gas.

Aug 05, 2015 | Dodge Cars & Trucks

1 Answer

How to change spark plugs

  1. Remove the ignition control modules.
  2. Clean the spark plug recess area with low pressure air.
CAUTION: Wear safety glasses when using compressed air, as flying dirt particles may cause eye injury.

NOTE: Clean the spark plug recess area before removing the spark plug. Failure to do so could result in engine damage because of dirt or foreign material entering the cylinder head, or by the contamination of the cylinder head threads. The contaminated threads may prevent the proper seating of the new plug. Use a thread chaser to clean the threads of any contamination.
  1. Remove the spark plugs from the cylinder heads.
NOTE: Allow the engine to cool before removing the spark plugs. Attempting to remove the spark plugs from a hot engine may cause the plug threads to seize, causing damage to cylinder head threads.
  1. Inspect the spark plugs. Refer to Spark Plug Inspection.
  1. Measure the spark plug gap on the spark plugs to be installed. Compare the measurement to the gap specifications.
  • Use only the spark plugs specified for use in the vehicle. Do not install spark plugs that are either hotter or colder than those specified for the vehicle. Installing spark plugs of another type can severely damage the engine.
  • Check the gap of all new and reconditioned spark plugs before installation. The pre-set gaps may have changed during handling. Use a round feeler gage to ensure an accurate check. Installing the spark plugs with the wrong gap can cause poor engine performance and may even damage the engine.
  1. Install the spark plugs to the cylinder heads.
  • Be sure that the spark plug threads smoothly into the cylinder head and the spark plug is fully seated. Use a thread chaser, if necessary, to clean threads in the cylinder head. Cross-threading or failing to fully seat the spark plug can cause overheating of the plug, exhaust blow-by, or thread damage.
  • Refer to Component Fastener Tightening Notice in Service Precautions.
Tighten the spark plugs to 20 N.m (15 lb ft) .
  1. Install the ignition control modules.

Jul 14, 2014 | 2006 Cadillac SRX

1 Answer

Bike breaks up at 2500-3500 rpms

Is it good above this rpm range or not.

Check for trouble codes.
2001 TOURING Diagnostic Trouble Codes (DTC) and Fault Conditions
12 MAP sensor
16 Battery voltage
24 Front ignition coil
25 Rear ignition coil
35 Tachometer
41 Crank sensor
44 Bank angle sensor (within TSM/TSSM)
detects possible theft attempt
52 RAM failure
53 ROM failure
54 EPROM failure
55 Ignition module failure

Battery condition and connections may cause misfires. Inspect for corrosion at battery terminals, main circuit breakers, ignition fuse terminals (GY and R/BK), right handlebar connector [22] and coil connector.

Fuel system problems may cause misfires.

Spark Plugs OFTEN cause misfires, even plugs that look good. If carbon tracking is evident, replace them.

Spark Plug Wires may cause misfires - Front/rear 20 in. 5,000-11,666 ohms. Wires must be clean and tight. Excessive wire resistance or faulty connections can cause coil damage. If carbon tracking is evident, replace the ignition coil and inspect the spark plug wires. Spark plug wire connectors can corrode and should always be coated with dielectric grease to prevent this. If there is any corrosion replace the corroded parts.

Coils may break down and cause misfires but not usually at a given rpm range only. Coil testing can be performed by substituting a known good coil for one causing the no spark condition. The coil
does not require full installation to be functional. Verify a possibly
faulty coil by performing a resistance test. Test the primary coil resistance on your coil. Disconnect all the wires going to the small terminals (primary) on your coil. Using a good ohmmeter on Rx1 setting, test the resistance between the two small terminals. You should read somewhere between 2 and 3 ohms. If you read more, the coil is bad. Before you do this test short out both leads of the ohmmeter and if the reading is not zero you will need to write down or otherwise remember the number and subtract it from the reading you get from the primary circuit test or you will have an incorrect resistance reading for the primary wires because you will also be reading the ohmmeter internal resistance and/or the wire and lead resistance added to the primary wiring resistance.

You can also test the coil by leaving the "hot" wire on the coil and replacing the other side (ground side) with a short piece of wire. Turn the ignition on and temporarily ground the short piece of wire you put on the "out" (ground) side. When you take the wire away from the ground, (which will collapse the primary current into the secondary) you should see a spark at the plugs if it is a wasted spark system or at one of the plugs if it is not a wasted spark system. If you have current to both sides of the primary of a two part coil both plugs should get a spark whether wasted spark system or not as you are energizing both sides of the primary and collapsing both into both secondaries at the same time when you remove the ground wire from the cylinder head ground.

Take the plugs out of the cylinder heads and lay them back on it so that they have a good ground. Then watch the spark plugs closely when you turn the ignition switch off. You should see a single spark on each plug. This tell you that the coil is getting fire and that it is good and your problem lies elsewhere. You get a spark on both plugs because it is a wasted spark system that fires both plugs simultaneously, one on power stroke and the other on exhaust stroke. This will not work on 2006 and later EFI as there will be no spark with both plugs removed.

Manifold leak Spray water around induction module seals with
engine idling. If RPM changes, change seals.

Improper fuel system pressure may contribute to one of the following conditions: 1.Cranks, but won't run. 2. Cuts out (may feel like ignition problem). 3. Hesitation, loss of power or poor fuel economy. Fuel pressure must be a steady running pressure of 55 to 62 psi (380 to 425 kPa).

Plugged, dirty air cleaner may cause rich misfire.
Plugged/dirty fuel filter may cause lean misfire.

Jun 03, 2012 | 2001 Harley Davidson FLHRCI Road King...

1 Answer

Change spark plug for 2002 kia rio

The spark plugs go straight down through the center of the cam/valve cover. You must remove the plastic cover going down the center to get to the wires and plugs.

With that said, I do not recommend that you attempt to replace your plugs unless you have a source of compressed air. The removal procedure includes "cracking the plugs loose and turning approximately 3/4 turn. Then place a blow-gun with a long tube down inside the spark plug tube and blow out any debris that is in the tube before revoving the plugs the rest of the way. Failure to follow this procedure can cause debris to enter the combustion chamber when the plugs are removed and can cause serious engine damage.

May 28, 2012 | 2002 Kia Rio

1 Answer

Cause of spark plug failure.

Usually it is because of fouling from either oil or too much fuel allowed to enter into the chamber. But bad spark plug wires (weak spark) could cause them to fail quickly.

Sep 02, 2011 | 1984 Mercedes-Benz 190

1 Answer

How to change spark plugs on 2001 chevy lumina

First, I would highly recommend that you also purchase a set of igniton cables and replace these also because you are most likely to have damaged spark plug boots when you remove the boots from the plugs. Trust happens about 95% of the time, and you will be way ahead of the frustration if you are prepaired.

Pull the spark plug boots off of the spark plugs.


Allow the engine to cool before removing the spark plugs. Attempting to remove the spark plugs from a hot engine may cause the plug threads to seize, causing damage to cylinder head threads.

Clean the spark plug recess area before removing the spark plug. (spray brake cleaner and compressed air works well) Failure to do so could result in severe engine damage because of dirt or foreign material entering the cylinder head, or by the contamination of the cylinder head threads. The contaminated threads may prevent the proper seating of the new plug. Use a thread chaser to clean the threads of any contamination.

Screw the spark plugs out of the cylinder head.
Check the air gap at the electrode end of the spark plug.

The specification for the plug gap on your vehicle is 1.524mm (0.060 in)

Place a SMALL amount of nickle-based antiseize compound on the spark plug thread, being very careful not to get any on the porcelain portin of the plug. If you do get antiseize on the porcelain part of the plug, it is imperative that you clean it off thouroughly using brake cleaner and a clean rag, otherwise it could cause cylinder misfires.

Screw the spark plug into the cylinder head and torque to specifications.
The spark plug torque specification for your vehicle is 15 Nm (11 ft. lbs.)

NOTE: Failure to properly torque the plugs can cause severe engine damage. Overtightening the plug can damage the threads in the cylinder head and/or make spark plug removal in the future impossible. This will cause you to have to remove the cylinder head for repair the next time the vehicle needs service on the spark plugs.
Undertightening can cause the plug to leak compression and damage the threads in the cylinder head. This can result in the plug blowing completely out of the head causing severe cylinder head damage.

When replacing the ignition cables, make sure they are routed EXACTLY as they were originally routed from the factory. Make sure that all protective wire loom and fasteners are transfered to the new wires and secured properly. Failure to do so can cause damage to the cables, engine misfires and can cause the spark plug wires to "spike" sensitive sensor circuits that are nearby and cause damage to the sensors or your computer modules. Improperly routed ignition cables have also been known to cause interference in radio and stereo systems.

HINT: The rear plugs on your engine are much easier to get to if you remove the two engine struts that go between the engine and the upper radiator support. You can then use a ratchet strap to pull the engine forward to get more room to work on the rear plugs.

Aug 12, 2011 | 2001 Chevrolet Lumina

1 Answer

I am trying to get a 1989 ford escort gl with a 4cyclinder 1.9 engine to start. The battery is good, theres gas, spark at the solenoid, not sure if theres spark at the plug. the rotor is new, no spring or...

a spark shows that ignition system is probably okay,but fouled spark plugs or out-of-time ignition could cause the failure to start. and another cause is no fuel or fuel system is not delivering a combustible air-fuel mixture. more possible causes are improper operation of valves, and loss of compression.

Jan 19, 2011 | 1989 Ford Escort

2 Answers

Code for cylinder #4 keep's on showing up changed that spark plug but still the same code ...

code for what? what is the code? what engine? have you checked the wire? fuel injector? compression?

Dec 21, 2010 | 1999 Chevrolet Tahoe

1 Answer

Car wont start but will crank dont know what it is

There are several things that can cause this to happen.
1) crank sensor has failed, it will result in no spark at the plug and no injector pulse.
2) Fuel pump circuit has failed, this could be caused by a blown fuel pump fuse, bad relay, vehicle security system failure or a failed fuel pump.
3) Ignition module failure, causing a no spark at the spark plug only.

Is or has the service engine light been on lately while driving?
If so, the vehicle would be scaned for trouble codes and will give a clue as to what the problem might be.

Oct 23, 2009 | 1992 Acura Integra Hatchback

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