I ordered the Yamaha accessory Akrapovic on my Tenere originally. I ran them for 18 months on a totally stock bike without any problem. The bike will not run lean with a standard airbox and filter.

The Akrapovic system offered by Yamaha isn't really much more free-flowing than the stock system. It has twin catalysts and quiet/restrictive dB killers. It is designed to run on a perfectly standard bike without fuelling changes.

Changes to the air intake are much more significant than exhaust/silencer mods when it comes to fuelling.

BTW, changing the CO setting will only affect the A/F ration at tiny throttle openings <2% and really won't make any significant difference to how the bikes feels/runs.

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