What is the purpose of the 02 sensor?  I understand that it has something to do with emissions compliance, but how does it work?  Is it part of the EFI system?  And if its removed, does it make inspection impossible for those States that check emissions?

It causes my bike to lurch below 4000 RPM.   

Actually, from what I understand, it is designed to send a signal to the ECU telling it to lean out the mixture if it detects unburned fuel in the exhaust gasses.

it makes your life miserable and costly. 

But at least it keeps the pressure-plate zombies at bay. 

So will its absence adversely affect emissions tests? 

It could.

Worst case, I say go get the emissions test done with the O2 sensor in, then when you're home just unplug it and plug the hole in your header.

Also, having just noticed your screen name:

http://cosbybebop.ytmnd.com/

ive wasted days on YTMND..captain jean-picard of the uss enterprise...... that ones pretty funny.

Theres noticebly more power on most of our bikes with the O2 in. But the bike idles better without it. you can try removing it, just make sure you take it out, otherwise you can risk damaging the sensor.

Quote from: Obsessed? on December 07, 2008, 02:36:40 PM
It could.

Worst case, I say go get the emissions test done with the O2 sensor in, then when you're home just unplug it and plug the hole in your header.

Also, having just noticed your screen name:

http://cosbybebop.ytmnd.com/

OMG that was funny!  "When I was a boy we'd play stickballllllllll"

Most of you folk have been driving cars with 0₂ sensors for the last two to three decades.  This is a closed loop system that constantly tunes adjusts fuel ratio as you drive.  The following is a brief and simplified explanation: 

Engineers knew, for many years, the best compromise between fuel economy, emissions and performance is 14.7:1.  This also happens to be the fuel ratio where catalytic converters work most efficiently.  14.7:1 is known as stoichiometric ratio, or Lambda.  The question was how to maintain this ratio.  The secret to this is the 0₂ sensor.  For simplicity sake I will stick to the units used on Ducatis, which are the same as the units used in most vehicles, the Zirconia sensor.  This sensor acts like a small battery, the difference between the ambient oxygen and the oxygen content in the exhaust causes a small voltage to be generated.  A lack of oxygen in the exhaust means rich and visa verse.  This signal is picked up by the ECU, and if parameters are met, the engine is in closed loop and mixture is constantly readjusted to maintain stoichiometric ratio.  Typically, cold start, warm up and wide open throttle are open loop.

Again, this is the short, generic, simple version.

long version - http://www.bikeboy.org/open_closed_loop_efi.html

Got a Cowboy Beebop t- shirt, now I gotta find a Cosby one!

Where the hell do they test scooter emissions? You gotta be kidding me.

Quote from: J.P. on December 08, 2008, 07:14:42 AM
Got a Cowboy Beebop t- shirt, now I gotta find a Cosby one!

Where the hell do they test scooter emissions? You gotta be kidding me.

I don't know, but I have a feeling that it will become common in the near future and I want to make sure I'm not doing anything to my bike that could make it fail.