The air cut-off valve smooths the transition off the throttle by briefly enriching the mixture, heading off the lean pop and backfire on deceleration. When its diaphragm fails you get popping through the exhaust on the over-run. A fresh valve restores a clean, quiet off-throttle transition. Fits the carburetors that use one, so confirm before ordering.

Replaces OEM #16048-425-671

• Cures deceleration popping and backfire
• Restores a clean off-throttle transition
• Confirm your carbs use this valve

Fits

• 1978 Honda CB400A
• 1979 Honda CM400A
• 1979 Honda CM400T