Exhaust smokes excessively

1. White smoke
   

• Piston oil ring worn.
  

  
  

• Cylinder worn.
  

  
  

• Valve oil seal damaged.
  

  
  

• Valve guide worn.
  

  
  

• Engine oil level too high.
  

  
  

1. Black smoke
   

• Air cleaner clogged.
  

  
  

• Main jet too large.
  

  
  

• Main jet fallen off.
  

  
  

• Start plunger stuck open.
  

  
  

• Fuel level in carburettor float bowl too high.
  

  
  

   

1. Brown smoke
   

• Main jet too small.
  

  
  

• Fuel level in carburettor float bowl too low.
  

  
  

• Air cleaner duct loose.
  

  
  

• Air cleaner poorly sealed or missing.