How's it going, I just bought a 2021Klx dual sport and I put a slip on exhaust on there that has the O2 sensor attached but still when I go downhill and shifting to a lower gear it sometimes pops or backfires. I was wondering if this will affect the engine or will the O2 sensor adjust to it. Or do I need to get a bigger snorkel? Not looking for performance, I got the slip on just for the sound. But will taking off the snorkel or getting a wider one affect the engine at all ( to lean/rich) or will the o2 sensor balance it out? My goal is to get rid of the backfire sound when downshifting and not scaring the Neighborhood thinking it's a drive by shooting every time I ride through. Thanks

 

I havent done the exhaust mod to my klx yet but Ive read that the 02 should adjust

 

When you're running partial throttle, the stock O2 sensor operates in a closed loop feedback mode to adjust your air/fuel mixture automatically. It may run lean under full throttle open loop conditions because the air/fuel ratio is preset for the stock muffler and air box.
I have no problems with running a highly modified exhaust system with the stock O2 sensor and a large KLX snorkel...



...because I use my bike for regular transportation and run partial throttle all the time.