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i have 2 completly newbie questions i bet you guys can help me with. It's about the air suction valve and air switching valve from the service manual (section 3). I'm not sure about the function of these and tried to google but still have some questions.
1. Air suction valve, from what i understand it is used to put extra air in the exhaust during normal operation so i guess this is the famous pairvalve i've been reading about everywhere but can't find in the servicemanual:) ?
2. Air switching valve, i got 2 hits on this one, either it's used to put extra air in the exhaust when the engine is cold or it helps control idle rpm and bypasses the throttels when closing them rapidly. Anyone knows the purpose of this valve?
 

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The secondary air injection system on the H2 is very similar to what many bikes have had for many years. Suzuki calls it PAIR, Kawasaki used to call it a "clean air system". The official EPA approved terminology is "secondary air injection".

Air is drawn from the intake air (after the air filter) to an ECU-controlled solenoid valve that they call the "air switching valve". The ECU controls the solenoid and that solenoid opens or closes the secondary air flow path, that's all there is to this valve, it isn't complicated.

Air that the switching valve has let through then goes into the "air suction valve", which is a separate one-way reed valve for each exhaust runner in the cylinder head. This makes use of the pressure and vacuum fluctuations in the exhaust runner. When there is a vacuum fluctuation, the reed valve opens and allows air to pass; when there is a pressure fluctuation the reed valve shuts and blocks the passage so exhaust doesn't flow backwards through the system.

The purpose of this is so that when the engine is running somewhat rich for whatever reason, it lets extra air into the exhaust runner which encourages the excess hydrocarbons and carbon monoxide to burn, and subsequently allows the 3-way catalyst to use the oxygen from that air to oxidize the HC and CO to (hopefully) carbon dioxide and water.

In the old days (before catalytic converters) that air switching valve was purely vacuum operated. It would shut during high vacuum conditions to prevent excessive backfiring but it was normally open. Nowadays it's controlled by the ECU so that it can optimize operation of the catalytic converter.

This system has nothing to do with regulating idling speed. This is a drive-by-wire engine; the ECU regulates the idling speed by operating the main throttle. It has no need of additional components in order to do this.

I know people like blocking-off or disabling anything that has to do with emission controls ... but in view of the complexity of the electronic controls on this engine, I think it is better left alone. There is no performance advantage to be gained by blocking off secondary air. It has no effect on how much power the engine makes. It's a tiny bit of weight and it's a few extra hoses - big deal.
 

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As GoFaster said it is to feed extra oxygen to the Cat to encourage emission control. You need to block it off though if you want to use WB O2 sensor to tune the engine. The extra oxygen will cause the sensor to miss read the AFR as lean.
 
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