Where should the O2 sensor locate?

I thought perhaps it's better to start a new thread instead of hijacking someone's...

Anyway, I am thinking of welding the EXUP valve back to the aftermarket exhaust system (Delta Barrel 4 in my case)

In the Euro speced bikes, there's an O2 sensor sitting IN FRONT of the EXUP valve...

But when I dynoed my bike, I realized that the dyno machine is picking A/F ratio slight further back, towards the end (The Delta has a small cat in the mid-pipe, so the probe could not go in further)

So the question is, if I weld back the EXUP valve and go for a dyno, where is the IDEAL location to pick up the A/F ratio?

Is it BEFORE the valve or AFTER the valve?

Let the experienced share the experience... thanks

I would probably put it before the valve, but I don't think it would really matter. I believe the big thing with the O2 sensor is that it is getting warm enough from the exhaust to give an accurate reading. My understanding is that they are not accurate at all until they are quite hot. On that note, I wonder if making an adapter to the AIS flange would work for those that don't already have an O2 sensor, but want to have a DIY A/F meter.

On the NA version of the WR there is a boss on the exhaust which I believe would be tapped for the O2 sensor on the European models. It's kind of late and dark here at the moment so I'm not going to check it's precise location with respect to the EXUP valve just at the moment. If no one else posts the answer I will do so tomorrow.

Interesting that in your country you have the 'European' model. It seems like there are three models. CAlifornia, the rest of North AMerica, and the Rest Of the World. (CA, NAM, ROW)

There



Because I am thinking about the alternatives...

When I put back the EXUP valve, I would have 2 ways of doing it

1. just cut out the valve unit and sandwiched it to the aftermarket mid-pipe


2. cut the stock pipe right after the valve, and weld it to the aftermarket mid-pipe


With approach 1, I will have 2 welding points... and I can only obtain the A/F ratio at a point that is AFTER the EXUP valve...

With approach 2, there will be only 1 welding point, and I get to keep the O2 sensor mounting... and since I have the O2 sensor mounting, I might as well put back the O2 sensor and ditch the PCIII (make sense? )... However, I have not came across any information on the stock A/F, and perhaps PCIII is still better...

Man I am confused

The only place I saw an O2 sensor was right after the EXUP, and that was modded on an R6.

isnt the o2 sensor up front on the header on the euro bikes?
so do you have any hard evidence that having a flapper valve blocking your exhaust is helpful? i cant see that helping efficiency?

Well, variable back-pressure does seem like a good idea if it works.


I looked on the bike today and the boss that I figured would have been where the O2 sensor would go is actually directly across from the valve head. So, it's probably something to do with the valve. I guess my theory was likely wrong.

There's a kup and scoot race this weekend, so I won't be tracking this week

Hence, I might go ahead and chop my stock pipe and perform the cut-n-paste

I will update the outcome, but maybe without the dyno first