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Old 06-02-2019
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Oldscool Oldscool is offline
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Been thinking about what you wrote Nutty. You're explanation is based on both maps having the same base settings (air/fuel ratio and ign timing) except one is closed loop, which fine tunes to meet emission laws, the other isn't / doesn't. Correct?

However we don't know whether the 2 maps have the same base settings. The open loop map could have a more performance bias setting, seeing as it's to suit non genuine pipes that are not street legal (competition use only) Therefore it is quite possible my initial impressions are correct. Am I on the right track here?
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Old 06-02-2019
Nutty Nutty is offline
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When you screw the throttle on hard, the open and closed loop systems work almost exactly the same. The mixture under those conditions goes to a setting which produces maximum power. On a trailing or constant throttle the open loop system goes to its programmed setting, usually a tad rich, whereas the closed loop system takes in motor temp, spark advance, road speed, gear position and torque vector to lean off the mixture in order to save fuel and lower emissions.

On Harleys they often use an open loop at low rpm to overfuel the motor and further assist the air-cooling. A lot of modded HDs reek of unburnt fuel at traffic lights, this is why.

All rego'd bikes will have closed loop tamper-proof systems soon, they won't get through Euro 6 without it. Harley recently stopped selling their supertuner because it makes even a stock motor non-compliant.

In performance applications the closed and open loops work exactly the same so there's no point fitting O2 sensors to race bikes.
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