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10.1 - Engine Lacks power

  1. Examine the Drive Train – Raise the wheel off the ground and spin by hand.

Does the wheel spin freely?

NO      -  Brake dragging, improperly mounted brake pads

  • Worn or damaged wheel bearings
  • Bent Axle

     YES     -  Go to STEP 2


  1. Check the Tire Pressure – use a tire pressure gauge to check the tire pressure of each tire.

Is the tire pressure correct?

NO      -  Punctured tire and/or inner tube

  • Faulty tire valve

     YES     -  Go to STEP 3


  1. Clutch Inspection – Accelerate rapidly through first and second gears.

Does the engine RPM/speed decrease properly when you shift from first gear to second gear?

NO      -  Slipping clutch, adjustment needed

  • Worn out clutch discs and/or plates
  • Weak clutch springs
  • Contaminating additive in the engine oil

     YES     -  Go to STEP 4


  1. Engine Performance Inspection – Accelerate lightly.

Does the engine speed increase?

NO      -  Clogged air filter

  • Restricted or clogged fuel line and/or fuel filter
  • Clogged muffler/spark arrester
  • Choke valve is closed
  • Clogged fuel tank breather hose

     YES     -  Go to STEP 5


  1. Spark Plug Inspection – Remove the spark plug and inspect

Is the spark plug in good working condition?

NO      -  Spark plug is not serviced frequently enough

  • Incorrect spark plug heat range
  • Incorrect spark plug gap

     YES     -  Go to STEP 6

  1. Engine Oil Inspection – Check the oil level and the condition of the oil.

Is the engine oil level correct and in clean condition?

NO      -  Oil level too high

  • Oil level too low
  • Contaminated oil

     YES     -  Go to STEP 7


  1. Cylinder Compression Inspection – Check the cylinder compression

Is the engine compression normal?

NO      -  Valve stuck open/seized or improper calve timing (see your local AJ1 dealer)

  • Worn cylinder wall and/or piston rings (see your local AJ1 dealer)
  • Leaking or damaged head gasket (see your local AJ1 dealer)

     YES     -  Go to STEP 8


  1. Carburetor Inspection – Disassemble the carburetor and check for clogs

Was the carburetor clogged and/or dirty?

NO      -  Go to STEP 9

     YES     -  Carburetor is not serviced frequently enough

  • Contaminated fuel


  1. Over Heating Inspection – Check the engine for overheating.

Is the engine overheating?

NO      -  Go to STEP 10

     YES     -  Excessive carbon buildup in the combustion chamber

  • Use of poor quality oil
  • Clutch slipping
  • Lean fuel mixture or improper octane rating of fuel


  1. Engine Condition Inspection – Accelerate rapidly through all gears and ride at high speed

Does the engine knock?

NO      -  Go to STEP 11

     YES     -  Worn piston and cylinder (See your local AJ1 dealer)

  • Wrong type of fuel (octane rating)
  • Lean fuel mixture
  • Excessive carbon buildup on the combustion chamber


  1. Ignition Timing Inspection – Only attempt these procedures if you are qualified and have the proper tools needed. Otherwise, see your local AJ1 dealer or a motorcycle repair shop to have the ignition timing and engine lubrication system inspected.

Is the ignition timing normal? (Timing is non-adjustable)

NO      -  Faulty CDI ignition box

  • Faulty ignition pulse generator

     YES     -  Go to STEP 12

  1. Lubrication Inspection – Remove the valve adjustment covers on the cylinder head and inspect the system for lubrication.

Is the valve train being lubricated properly?

NO      -  Clogged oil passage (see your local AJ1 dealer)

  • Dirty and/or contaminated engine oil

     YES     -  See your local AJ1 dealer to have your motorcycle serviced.

Previous article 10.2 - Trouble Shooting - Poor Performance at Idle and Low Speed
Next article 9.5 - Chain Adjustment & Replacement