The CB1100 Community Forum

At the risk of sounding stupid, is there a difference between the O2 sensor and the PAIR valve?

All my packaging is labeled for off road use only
However, after a little more scrutiny, I did find the O2 sensor bung.

(02-25-2015, 10:12 AM)EmptySea_imp Wrote: [ -> ]At the risk of sounding stupid, is there a difference between the O2 sensor and the PAIR valve?

Nope it is not, .... if you search for it, you will actually find a lot of info about it here in this forum... but here is the short version:
The PAIR Valve is required ( mostly by california law ) to keep emission legal, it is a mechanism/valve adding fresh air to the exhausted air. It's mounted on the cylinder head.
O2 sensor is actually installed in the exhaust header just before the catalytic converter. ECU uses the reading of this sensor to create a air/fuel mixture perfectly suited for optimum function of the catalytic converter which is far away from the optimum fuel/air ratio for best performance.
That's why when you buy a PCV you get a bypass plug for the 02 sensor, otherwise the PCV and the ECU would constantly "fight" over the air/fuel ratio reading ...

Thanks! Very informative. I don't have a PCV. I'm running the stock ECU with my Yosh exhaust. The PAIR valve is blocked to prevent some of the popping and, at least so far, everything seems to be running smoothly. I wasn't looking for performance increases, though.

(02-25-2015, 11:16 PM)EmptySea_imp Wrote: [ -> ]Thanks! Very informative. I don't have a PCV. I'm running the stock ECU with my Yosh exhaust. The PAIR valve is blocked to prevent some of the popping and, at least so far, everything seems to be running smoothly. I wasn't looking for performance increases, though.

You already have a bit of a performance gain due to lost weight and no resistance for the exhausted air due to the missing catalytic converter. So the engine is going to be a bit more rev happy.

Optional:
The PCV will make your engine run cooler, since your air/fuel mix will be more rich, but as you said, if you are not looking for more HP and torque .... you will be just fine.

I personally will make a setup, where i can change the fuel map via a switch. One map will be for my commute and extremely fuel saving ( gas tank is really small ) and the other one to have some fun on weekend rides.

The Yoshimura full system is being installed either today or tomorrow. Will be riding Sunday so a report shall follow

The stock pipes are off the DLX. Boy are those suckers stout. The system is a pair of 2 into 1's, left and right, no crossover.
There is an O2 sensor for each side. The right side sensor goes into the Yosh collector, the left side gets unplugged from the harness and the sensor eliminator (not included) plugs in its place. The eliminator was supposed to be here yesterday with a few day window. I'm hoping it at least gets here Saturday at the latest so we can ride Sunday.
Lee, who is my buddy, ace lifelong Honda mechanic is also putting the drag bars on, with a 1" riser for now. I really want them up at least 2 inches from stock eventually. Also getting the bar end mirrors on too. The Chic seat's not due to arrive till the end of March

Looking forward to pictures Motogeezer.

I'm a complete exhaust ignoramus. I can see that having an O2 sensor waving around in the breeze might misinform the ECU, but can you tell me what would happen if you just unplugged it?

Nothing bad, unless there was a true malfunction! The computer would show a code for it and go into open loop, as evidenced by the celebrity bike builder thread who just put a sticker over the check engine light.

So, if you want to go for a ride on Sunday, you could get a sticker to tide you over?