Yamaha FZ1-N Service Manual

Contents

AIR INDUCTION SYSTEM7-14EAS27060CHECKING THE AIR INDUCTION SYSTEMAir injectionThe air induction system burns unburnedexhaust gases by injecting fresh air (second-ary air) into the exhaust port, reducing theemission of hydrocarbons. When there is neg-ative pressure at the exhaust port, the reedvalve opens, allowing secondary air to flow intothe exhaust port. The required temperature forburning the unburned exhaust gases isapproximately 600 to 700°C.Air cut-off valveThe air cut-off valve is controlled by the signalsfrom the ECU in accordance with the combus-tion conditions. Ordinarily, the air cut-off valveopens to allow the air to flow during idle andcloses to cut-off the flow when the vehicle isbeing driven. However, if the coolant tempera-ture is below the specified value, the air cut-offvalve remains open and allows the air to flowinto the exhaust pipe until the temperaturebecomes higher than the specified value.1. Check:• HosesLoose connections → Connect properly.Cracks/damage → Replace.• PipesCracks/damage → Replace.2. Check:• Reed valve “1”• Reed valve stopper• Reed valve seatCracks/damage → Replace the reed valve.3. Measure:• Reed valve bending limit “a”A. From the air cleanerB. To the cylinder head