Bung Relocation

[ncrider]

I have a set of V&H Big Shot Staggered pipes (my favorites) that need the O2 bungs re-worked.  They may or may not need to be relocated but they do need to be seated deeper.  There is not enough thread to allow shaving it for deeper seating so I'm sure they will need to be replaced.  Who can I get to do this?  Do any of the shop guys on here do that?

[Ohio HD]

You can do it easy enough. Buy the bungs, then drill a hole, have a local weld shop take care of it.

http://harleytechtalk.com/htt/index.php/topic,55047.msg582328.html#msg582328

http://harleytechtalk.com/htt/index.php/topic,55047.msg582329.html#msg582329

http://harleytechtalk.com/htt/index.php/topic,55047.msg582439.html#msg582439

[HogBag]

12 or 18 mill bungs  

[joe_lyons]

The bungs themselves need to be milled for proper depth.  Pretty much measure the thread length on the o2 sensor and the bung should be about that long with a small step to go into the pipe.  Shoot for the outside of the bends for best signal, not always the prettiest but good signal.  Need to be within 5 or so inches of the exhaust port for keeping temp up.

[ncrider]

12 or 18 mill bungs  

18 mm bungs.

[ncrider]

The bungs themselves need to be milled for proper depth.  Pretty much measure the thread length on the o2 sensor and the bung should be about that long with a small step to go into the pipe.  Shoot for the outside of the bends for best signal, not always the prettiest but good signal.  Need to be within 5 or so inches of the exhaust port for keeping temp up.

There are only about two turns of threads in the original bungs so they will have to be replaced.

[joe_lyons]

Yes I was talking about replacement bungs.

[HogBag]

My Bassani road rage had the bung in the wrong position on the rear header but in a OK position on the front header. The sensors depth was way out with only the tip in the exhaust flow. My first mod was cutting them down to get the sensor in the flow but that failed. My next bung mod was cutting them off and going with the bosch angled spec in the same location but this failed to get a good signal at low revs. My next bung mod with to cut them off again and go straight into the pipe with the whole sensor being in the exhaust flow with the 18mm thread screwing in level inside the pipe. Success this time around as my tune seems to be holding well after a few months riding. If mk3 failed I was going to blank them off with bolts and mount them on the outer curve but I wanted to try and keep them out of sight as I didn't like the idea of the sensor and wire hanging out the side of the bike.
Good luck

[07heri]

My Bassani road rage had the bung in the wrong position on the rear header but in a OK position on the front header. The sensors depth was way out with only the tip in the exhaust flow. My first mod was cutting them down to get the sensor in the flow but that failed. My next bung mod was cutting them off and going with the bosch angled spec in the same location but this failed to get a good signal at low revs. My next bung mod with to cut them off again and go straight into the pipe with the whole sensor being in the exhaust flow with the 18mm thread screwing in level inside the pipe. Success this time around as my tune seems to be holding well after a few months riding. If mk3 failed I was going to blank them off with bolts and mount them on the outer curve but I wanted to try and keep them out of sight as I didn't like the idea of the sensor and wire hanging out the side of the bike.
Good luck

Short of heating up the pipe and flaring the top in, the way you described is really the only way.  I shaved mine down as far as I could and it didn't make any difference in low RPM tuning.  I don't think having 3 or 4 threads length of bung sticking inside the pipe is going to make a difference.  But it will get the sensor all the way in.  I have my head pipes off right now and there's really no other way, if keeping in line with the Bosch specs is a priority.  The biggest issue, on an OEM headpipe, is getting it in deep enough and still being able to get a wrench on it to tighten it up. 

I'm starting to think it would be easier to weld bungs on the curve, tune it, plug them and put the sensors back in the original bungs, and run it open loop 2500 and below.  Up to this point I've pretty much guessed down low by feel and sound.  But it would definitely be nice to get it to sample more accurately down low. 

[mkd]

when i had my supertuner installed and the bike dynoed they had a kit that they drilled holes and installed  bungs without any welding in the stock exhaust headers under where the heat shields are installed.  drilled the holes and somehow installed the threaded bungs and that's were they put the sensors for the dyno tune. when they were done tuning they just installed plugs in the holes. i thought pretty slick!

[redmtrckl]

I believe the main reason OEM sensor locations don't work or quit working for low speed tuning is because the mufflers have been changed and there is not enough back pressure in the head pipe. Same with after market exhaust systems. Some of the MFGs have addressed this problem and some haven't. I don't think the wide band self heated sensors have as much of a problem. Due diligence on location and depth is required.

[wolf_59]

I use 18x1.5mm half nuts they work pretty good and only about .030 thicker than the threaded portion of the sensor so no threads exposed to the exhaust to get carbon in them. I just turn them round in the lathe for looks and elongate the holes in the pipe so they set flush on the sides and inset on the ends gives good protrusion in the exhaust stream

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