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Old 05-07-2013, 08:47 AM   #7
Head2Wind's Avatar
Joined: Mar 2006
Location: NorthWet Washington
Oddometer: 2,582
The SAS is a passive (no forced pumping) system as far as the injection of air into the exhaust system, so it requires a pressure depression in the exhaust port to allow air to flow past the reed/check valve and into the port. When valve is activated and air is flowing into the port, this will make the exhaust appear more "lean" to the O2 sensors and the ECU "should" react with more fuel, which with these engines tends to mellow them out on the twitchness meter. These engines also tend to respond well to pulling back the timing a little at small/low TPS openings, which indirectly effects the AFRs that the O2 sensor sees (goes richer when less advance).......

You can read the many threads about tuning and using the TuneECU app, eliminating the 2nd throttle plates or modifying their action in the ECM. There are many opinions on how this affects the ridability of the bike and whether its good/bad. Generally people will maintain the secondary plates to soften the hit.
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