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The Keihin CV carburetor

NOTICE: The terms slow, idle, and pilot are used more or less interchangeably in Honda manuals and Keihin carburetor documentation.

Side view
- Air intake from the airbox.
- Choke valve seat.
- Pilot screw seat.
- Duct for the high intake vacuum that acts on the air cut-off valve diaphragm.
- Air cut-off valve: air in (normally open).
- Air cut-off valve: air out.
Float chamber
- Main jet
- Slow jet
- Starter jet (choke/enrichment jet)
- Float valve
- Breath hole
Vacuum chamber
- Air intake for the air cut-off valve: normally open. It closes on deceleration (high rpm + throttle closed).
- Air intake for the slow jet.
- Air intake for the choke.
- Small vent that connects the chambers above and below the diaphragm: it acts as a vacuum/pressure control and damping system.
Airbox view
- Air intake for the pilot/idle and the air cut-off valve circuit.
Engine view, bottom
- Primary pilot outlet port. This is the main idle fuel outlet, controlled by slow jet and pilot screw.
- Pilot progression ports. They provide staged extra fuel during throttle opening.
Engine view, top
- Vacuum conduct that operates the air cut-off valve.
Slide, diaphragm, needle
- Slide lift holes: vacuum bleed holes that control how quickly pressure changes reach the above diaphragm chamber.
Float bowl
- Drain screw.
- Drain conduct.

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