Hello,98 Road King here.
I am wondering if any of you have welded a o2 sensor bung to your stock 2 into 2 header pipe so you could use o2 sensors? I am trying to get away cheap because I've not worked in a year and I do have the autotune kit that goes along with my power commander 5 i'd like to utilize to get better performance than I do now with my mmi. If so, how far from exhaust flange did you go, and did it work for you as planned? I am not switching to carb. Thanks in advance. .

 

I've welded plenty of bungs onto car systems. Look at where the MoCo put the bungs on the later bikes, up near the port, sort of, and put it about there. On the Sportster, I put it down by the lower frame bend. It works fine. More of a convenience thing really, but closer is generally better, as you will get more heat at that point, which brings an unheated sensor up to operation sooner. Too far aft and you have the issue of oxygen sneaking in from the back. You really only need it in one header. If one cylinder is tuned, the other will be OK and you probably don't have the ability to tune individually anyway.

If you look closely in this pic, you can see the sensor down by the right foot area in front of the brake pedal where the pipe makes the bend back:

 

Thanks for responding. I am trying to utilize my autotune attachment for my power commander 5, and just can't afford pipes right now. Mt only question at this point is where I could install the os port on the back cylinder on the stock 2 into 2 crossover pipe. How do you know if it should be angled or straight?

 

I would put it in straight and not put it in the crossover pipe, but in the part between the exhaust port and the crossover.

 

I just put one on on Old D&D exhaust system for my 98 Fatboy. it's about 4 1/2 to 5" down the pipe.. the attached picture showing position and everything works very good..

 

I would add it to the front header as the MMI head temp sensor reads this temp to adjust fuel. Please post up after you have done this install of how it works, what you did and what you like. I have been thinking of upgrading to a newer tuner myself.

 

The dynotune autuner has 2 o2 sensors, so why would I just put it on the front and not the rear? I believe the power commander 5 will add/decrease fuel to each cylinder as needed, and that's it's purpose. I will post pics when I do this.

 

When I get back to work I am getting the D&D fatcat.

 

With MMI or EFI you will need the 2 o2 sensors. One front and rear. I only have one cause I'm carbureted and with a carbureted motor the front will run richer than the rear so you tune from the front cylinder.. Can't go wrong with a Fat Cat... Mine has a louvered baffle with no fiberglass.. it's pretty loud.. my buddy's put me to the rear of the pack..

 

I was under the impression you were only needing/ wanting one. No worries. If you need 2 get her done. I'm running a 2-1 set up that I plugged the O2 bungs. If you need measurements I'll be glad to post them up.