The Honda CBX Engine

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• The Honda CBX Engine
• By MAE 388 Design Team 5
• A.Kerner, T.Doehner, J.Doyle, N.Karas
• Model Year 1979

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Key Advantages

• Double-overhead cams power 24 valves which feed
  the motor through constant velocity carburetors
• Only two inches wider than the four cylinder
  Honda CB750 it replaced, boasting a 5-speed
  gearbox and svelte clutch
• Produces 105 HP (76.6 kW) at 9,000 rpm. For a 500
  lb bike, the power generation is rather
  remarkable
• If todays sports cars possess a 101
  weight-to-HP ratio, then the Honda CBX has a 51
  weight-to-HP ratio for 27 year-old technology,
  this is quite impressive
• First motorcycle engine to boast six cylinder
  inline configuration, which allows for the bike
  frames size to be smaller as opposed to having a
  V-6 cylinder configuration
• 6-cylinder configuration allows for a higher top
  end speed, horsepower and smoothness than
  previous inline configurations

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Key Disadvantages

• Too many moving parts
• Extremely expensive to maintain and is rather
  heavy
• Carburetors were very hard to maintain properly

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Key Features

• There are two individual gears located in the
  engines top center which govern the air
  intake/exhaust ports

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Piston Firing Order

• The firing sequence for the pistons is
  1,5,3,6,2,4 which leads to maximum power
  generation per stroke

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Valve Train

• The Honda CBX valve train is very unique in that
  it guides valves that can be opened/closed
  dynamically, thus maximizing power output and
  fuel consumption based on operating conditions

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Overall Engine Setup
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Disassembly of Engine Setup
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Future Improvements Considerations

• Overall weight reduction, which would directly
  lead to a more optimal weight-to-HP ratio
• Provide more engine torque by reducing the
  carburettor size
• Electronic ignition

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References

• www.honda.com
• www.bikez.com
• www.cbxworld.com
• www.chuckhawks.com