REF: General-MSR 03


Basic Troubleshooting

Troubleshooting can be very difficult sometimes to the person that has to physically do it.
You're there. You hear it or see it and sometimes the hardest thing to do is to tell it to someone else.
Another hard thing to do is to detach yourself from what you (think or believe so strongly in) to strictly what you can prove.
It all boils down to your specific belief system.
You filled it full of oil last week so it couldn't have been too low, so you didn't check that.

I.E., previously unknown to you, your friend on the back burnt their leg or foot on the exhaust on a long trip.
Then they went berserk and not realizing that they kicked the oil line damaging or kinking it on a long trip.

When you believe that anything could have happened to it, you stand a better chance of diagnosing the problem.
Below are some easy fixes and some very difficult ones as well as cheap and expensive ones.
Keep in mind an unhealthy bike doesn't care if you can't afford it or know anything about it. 1)

All engine noises aren't good noises but it is a Harley and it's gonna be loud and it's gonna shake.
The front forks may appear to want to leave each other and your hands may feel a little numb after riding.
It's OK, it's suppose to do that.

See also Hunting Down Sportster Noises for help in diagnosing noises.

Engine oil is like blood in the veins. Running a bike too low or without will ultimately lead to engine seizure.

  • High Oil Consumption
    • Worn/damaged piston rings 2)
    • Worn valve guides 3)
    • Improper chain oiler adjustment (if equipped) 4)
  • Excessive oil leaks
    • Clogged up air cleaner breather hose 5)
    • Damaged gasket mating surfaces 6)
    • Gaskets loose from non-torque/ loss of torque 7)
  • Excessive oil at crankcase breather
    • Damaged/ restricted oil lines/ fittings 8)
    • Leaking gearcase cover gasket 9)
    • Oil isn't returning to the oil tank 10)
      This is simply oil from the tank draining slowly back down into the crankcase while the bike is parked for any length of time.
      When you start the engine, the excess oil in the crankcase is fired out the breather, onto the floor, (or into your air-filter on post-79 models).
      The oil should stop puking after the engine runs a few minutes and pumps the excess oil back up into the tank.
      If the puking starts after you top your oil tank, this is probably the problem.
      If you fill the oil tank to the Full mark while some oil has wet-sumped down into the engine, you have too much oil in the system.
      The oil from the sump will be pumped back up to the tank, dribble down the vent tube to the timing cover, from where it is fired out the engine breather.
      This puking will continue after initial start up until all the excess oil has been fired out, which can take a while.
      The cure is to drain a quart or so out of the oil tank, run the engine for five minutes til the puking stops, then top up the oil tank to the full mark.
      DO NOT be tempted to drain oil out of the sump by taking out the threaded drain plug under the front of the engine (if equipped).
      These are notorious for stripping the threads and are very difficult to repair properly.
      In most cases the plug is factory installed and is not intended to ever be removed.
      If your engine breather continues to puke oil or blow smoke after the above two things have been eliminated,
      Your problem is most likely wear in the cylinders and heads.
      Worn rings and even valve guides, can allow blowby of combustion gasses into the crankcase area, which then comes out the breather.
      Usually this will be accompanied by smoke or oil coming out the exhaust pipes too.
      A compression test will give some indication of top-end condition.
      Anything below 120psi is suspect, according to the factory manual.
      These bikes will still run ok at even 100psi, but they will be down on power and consume oil, and blow fog out the breather pipe. 11)
  • Oil isn't returning to the oil tank
    • Damaged/ restricted oil lines/ fittings 12)
    • Oil pump not working properly 13)
    • Engine too low of oil
    • Oil pump Scavenger gear woodruff key sheared off/ broken 14)
    • Stopped up oil filter
    • Faulty check ball at filter housing
    • Faulty oil pressure regulator
  • Engine Overheating from excessive load
    • Engine oil level too high.
      Adding too much oil to the oil tank/ engine causes undue pressure in the crankcase which degrades engine performance and increases heat 15)
    • Oil viscosity too high.
      Using heavier than recommended oil can damage the oil pump, oiling system and cause engine to drag and overheat 16)
  • Engine Overheating from poor lubrication
    • Engine oil level too low which increases friction
    • Wrong oil viscosity/ degraded oil viscosity
  • Change in Engine Vibration due to degraded oil
    • Vibration analysis can pick up subtle vibration changes.
      You also may be able to identify lubricant starvation before the extreme heat from friction is discovered. 17)
  • Engine running poorly on acceleration
    • Oil viscosity too high.
      Using heavier than recommended oil can cause engine drag
  • Engine running poorly with continuous high revs
    • Wet sumping occurs when the crankcase fills up with oil.
      The crank has to turn in an oil bath when it's really designed to run in open air.
      The crank running thru the oil heats it up and adds lots of bubbles.
      It also really cuts down on the available power.
      The scavenge pump picks up the oil and sends it to the oil tank.
      The hotter the oil, and the more air bubbles in the oil, the harder it is for the scavenge pump to move the oil.
      So, the oil collects in the crankcase even more. 18)

Engine Overheating

Engine Noises

The tables below have 2 separate but equally important columns; Possible causes and Possible affects. It is just as is important to know what happened as it is to know why it happened. I.E., a broken piston ring can be fixed but if the cause was low oil pressure and that was not addressed, it'll happen again or worse.

Noises coming from the top end Possible Causes Possible Affects Possible Remedies
Valve Noise Lack of Lubrication at high RPMWorn or seized lifter(s) Check oiling system, Inspect/Replace damaged parts
* * Broken or weak Valve Springs Check oiling system, Inspect/Replace damaged parts
* * Worn Cam Lobe(s) / Rocker Arm(s) Check oiling system, Inspect/Replace damaged parts
* Bent pushrod(s)
* Mal-adjusted pushrod(s)
* Valve sticking in valve guide
* Damaged rocker arm/ binding rocker arm shaft
* Worn cam gears/lobes/bushings/bearings
Knocking or Pinging During Accelleration Carbon buildup in combustion chamber Use a fuel additive to dissolve carbon particles/ Remove heads and de-carbonize chamber, pistons, valve components
* Too low octane/ Poor quality gas leading to detonation Pistons rattle against cylinder walls Drain old gas, replace with recommended grade of gas
* Wrong spark plug- Uncontrolled detonation indicates the spark plug heat range is too hot Excessive heat buildup in the cylinders can lead to catastrophic failure of engine parts Install the proper heat rated spark plug and recheck
* Air/Fuel mixture not set properly Heat buildup leading to detonation Tune the air/ fuel mixture setting for proper operation
Pulsing On/Off/On/Off Squeal Head gasket leak Poor engine compression Replace head gasket(s)
Piston Slap/ Rattling Sound Cylinder to piston clearance out of service limit Remove pistons, clean pistons and cylinder bores. Measure ea. piston and it's corresponding cylinder bore. Subtract the piston dia. from the bore dia. and this is the 'piston clearance'. Check that clearance against the specs in the FSM. Replace piston/ Bore out cylinders as required
* Over-revving, trying to start a badly flooded engine, ingesting a foreign object into the combustion chamberBent connecting rod, cracked piston Inspect/ Replace parts as needed
* Worn/ lack of lubrication of piston rings Piston rings worn, broken or sticking Inspect/ Replace parts as needed
* Piston wrist pin/ connecting rod/ top bushing worn, out of round, warped or seized Seizure of piston movement, piston not positioned properly, scratched or worn cylinder or rod
* Improper lubrication Piston/ring seizure or damage Inspect/ Replace parts as needed
Piston Slap/ Tapping Sound Improper piston to valve clearance due to mis-matched installation, weak valve spring(s), dropped/ bent valve Cracked piston, head, bent/broken valves Check piston/ valve clearance/ Replace parts as needed/ Consider thicker head gaskets if needed
Noises coming from the bottom end Possible Causes Possible affects Possible Remedies
Knocking or Tapping during deceleration Excessive rod bearing clearance Catastrophic breakdown Inspect/ Replace parts as needed
Constant Knocking and Vibration Worn out main bearings Catastrophic breakdown Inspect/ Replace parts as needed
From Primary Cover Side Engine hub nut coming loose Pull primary cover, check hub nut for proper torque

Engine Diagnostics


Transmission noises are usually not what you want to hear but there is a natural symphony that happens sometimes when changing gears. The harder the push is on gear shifter, the harder the shift forks smack the gears around and the noise is more audible than if shifting easier with a quick smooth motion which sometimes sounds like a light hollow clinking as in two plastic parts shaken in a sandwich bag.

Noises coming from the transmission Possible Causes Possible Remedies Possible Side Affects
Ka-Chunk while shifting Shifter pawl mal-adjusted \Bent shifter shaft \Bent, worn shift pawl Adjust pawl, inspect/ replace any defective parts Metal shavings in primary oil from pawl contact on clutch gear
Screech- Clickety Clutch is about to explodeCheck/ replace clutch 19)
Loose or damaged clutch pressure plate and/or bolts, gear teeth
Loose or damaged primary chain/ chain adjuster, gear teeth Pieces of nylon in oil/ passeges
Loose rivets/ broken friction plates in clutch pack
Clutch or flywheel nut loose
Loose or damaged shifter components
Transmission Condition Possible Cause Possible Remedies
Clutch Slipping Clutch cable may have stretched or may not be adjusted properly Re-adjust clutch cable and retry, replace if frayed/ kinked
* Friction plates/ metal plates worn/ warped Overhaul clutch assembly. Look into possible clutch upgrade
* Improper clutch pack heightCount/ measure friction and steel plates against factory/ after market known numbers/ dimemsions. Replace as needed. Best to replace all while your in there
* Clutch Diaphragm Spring broken or weakened from use or from heat Replace with a new one. Look into possible clutch upgrade
* Clutch pushrod bent Inspect/ replace if needed
* Wrong transmission oil usedDrain, wipe clean and install HD tranny oil or aftermarket oil (rated JASO MA,MA1 or MA2)
* Glazed build-up on friction/steel platesCan sometimes be cleaned but most often have to be replaced. The use of a thermally stable oil along with proper operating techniques/ adjustment will minimize the potential for glazing to occur 20)
Frequent clutch failureImproper rider operationDon't ride the clutch or downshift with too many RPMs
Clutch center or housing unevenly worn causing improper engagement of the plates Inspect/ replace if needed

Chassis Noises

Vibration Tech

A Sportster is gonna rumble and vibrate due to the engine configuration. New or distinct vibration can be a sign of problems however.

Vibration at certain times Possible Causes Possible Remedies Possible side affects
While letting go of the clutch Clutch discs slipping Replace clutch discsmetal in primary case/ oil
Rivets coming loose on clutch steel insert replace clutch discsCheck for disc/ metal fragments in primary case
* * *

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