oxygen sensor placement ,1994 Harley
 

Question for the ever giving and knowing brain trust here-
Where is the best place for this oxygen (AFR) sensor ?
I have part A ok , - front cylinder.
Next-
They say maybe 15 inches away from header flange . Or perhaps 6 " depending on engine temps....
What works best ?
Reading the instructions is for the generic engine. They want a few deg of tilt so nose dwn and tail up.
Got that.
But the wording of how far away for this engine, that engine, and of course no mention of a old V twin .LOL
To me me it looks like about 8" dwn from the header flange at the 1st bend would be it.
Will that be too hot?
I thought i would ask B4 punching holes and welding in bungs.
Thanx!

Also
should the bung be angled ?

Due to air flow, rear cylinder runs warmer. Would it make sense to get UR data from that pipe?

I would weld a bung into each pipe and split the diff between the 6 and 15" distance from the port at any spot which would tuck the sensor in to avoid either catching cloths on it or damaging it .
Leave one bung plugged and move the sensor back and forth after tuning to see if any significant difference shows up in cyl 1 vs cyl 2

I assume that you have only 1 sensor. What style exhaust are you running? Duel independent pipes or 2-into-1 setup?

Asphaultgambler - 2 into one (thunder headers )
Johnsjmc - I like that idea of a bung in each pipe, and swapping back and fourth.
LakeCleElum - From what i have read the front is more important then the rear as it always runs leaner.
If that is satisfied , the rear is what it is unless i convert to some kind of fuel injection .(not going to)
The more I think about it all - Once dialed in perhaps just remove the sensor and gauge.
Keep it for a tool.
This is a wide band sensor and will supposedly last awhile even with leaded fuel.
The directions are all over the place as for placement location.
Next
Should it have a angel built into the bung so the nose sort of faces the tail pipe ?

If using a 2 into 1 the placement for a single would be just after the collector. However tuning will only produce an average mixture between the 2 cyls. I would still do 2 bungs and use the sensor for tuning then after satisfied with the results you can remove it and put it in your toolbox as a tuning tool.
I don,t know if there is any way to compensate for a lean vs rich cyl when only using a single barrel carb. so tuning will be still a compromise.

well...I am still in a quandary of the placement or distance from header flange...Thats my biggest question with it all..

I would put the 1 sensor just after the 2-1 merge into the collector. Although, as I stated before, unless you have fuel injection - not a fan of these as long -term use. You would be surprised how that chunk of metal hanging inside the exhaust tube has a negative effect on flow. You should weld the bung just on top on the tube, not through to the inside lower to be out of sight. Then once you have the mixture set - remove it and plug it.

OK
On my way to do something here....
Thnx