pulse secondary air injection system

[bvg123]

does any one know what the pulse secondary air injection system is and how it functions.

[ct1500]

Yup

[WingAdmin]

does any one know what the pulse secondary air injection system is and how it functions.

When you close the throttle, the mixture gets rich, which means unburned fuel (hydrocarbons) get blown out the exhaust. Totally normal, doesn't hurt the engine, but it is horrible for emissions. The fuel doesn't burn because of the rich mixture - there isn't enough oxygen to burn all the fuel in the mixture.

So when the bike's engine ECU detects high intake vacuum from the throttle being closed, it opens one or both PAIR solenoids. The exhaust pulses draw fresh air (oxygen) through the solenoid valves into the exhaust, where it hits the unburned fuel and causes it to finish burning. That way by the time the gases exit the tailpipes, there is no unburned fuel remaining.

The bike will operate exactly the same without the PAIR system, but it will put out a lot more exhaust emissions when decelerating.

[bvg123]

so if this had been a fuel injection engine this would not be necessary. kinda like a 02 sensor

[Rambozo]

so if this had been a fuel injection engine this would not be necessary. kinda like a 02 sensor

True. A carburetor is basically a kludge of compromises.

[bvg123]

thanks for all the info.