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I have just taken ownership of 175hpE'tech and find that at 1900-2100rpm (which incidentally is right on my trolling speed) the motor exhibits a very low level noise like a cough. Much like the noise you get from a typical 2 stroke if you lean out its mixture too much. This is fairly slight and seems not to result in any perceptible vibration. Coincidentally a friend has a 115 that is showing similar traits. Mechanic says that it is when the engine is transfering from stratified mode to homogenous mode. Your advice please. Also I note that optimax with smart guage enables electronic control of rev range. Does Evinrude have something similar? PS the motor has had latest software change incorporated.
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Hello engine noise is normal at that rpm and can try different prop like 4 blade  to help. 

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