Using an O2 Sensor to tune carbs?

I've been looking up O2 sensors and I want to try and use them as a tool to tune the carbs. I am NOT looking to permanently install the sensor but rather the way that I'd do it is that I'd remove the exhaust EXCEPT the headers. I would then take the actual sensor and insert it at the bottom of each of the exposed headers (where it connects to the collector), turn on the bike, and start adjusting. I would only use it for idle purposes NOT for going up and down the rpm power band although I'll most likely experiment.

My first question is, would removing the collector and the mufflers have an effect on the actual air/fuel ratio?

I know that there are for bung holes at the bottom of the header for when Yamaha use to be able to hook up their fancy machines but those holes are not big enough to fit an actual sensor and I don't really want to start drilling additional holes into my exhaust.

This is the product I'm planning on purchasing: https://www.ebay.com/itm/52mm-LED-D...798054?hash=item2644e7c866:g:5okAAOSwLSBfT0Ob

In theory it seems to work and I'm kind of excited but I don't know enough about the science of exhaust and air/fuel ratios and stuff like that. I'm also worried removing the muffler and collector would have an effect on the readings but again, I only want to adjust the carbs at IDLE so maybe removing the muffler and collector would not factor in as much.
Please don't suggest Colortunes. I know all about them thank you very much. Please just stay on this topic.

Looking forward to your thoughts and suggestions.

 

There are sniffer ports in the stock headers.
The use of a probe shoved up the headers comes with the problem of restricting backflow into the header so you don't get a false reading.

You should be able to make a sniffer-type probe from a few fittings and the appropriate size of copper tubing. The trick will be calibrating it to allow for the O2 sensor not being directly in the gas flow. You'll also need to use a heated O2 sensor.

 

http://www.scirocco.org/tech/misc/afgauge/af.html
if you reduce that to a simple test tool all you need is a heated wideband O2 and a volt meter and 12 volts

 

So that link you sent is WAAAAY more complicated then I can understand. I'm just looking for a plug in play simple tool.
How would I make the simple test tool and please, explain it like I'm a 10 year old.

 

So there in lies the question, how do you make a sniffer-type probe?

Also, I don't quite understand your first statement. How would I be restricting backflow exactly? I would not be covering up the headers with the sensor. There would still be an opening for the exhaust to escape. Are you saying just putting that little sensor in there could change things.

 

If it helps, here is a diagram of how I would use it. Please excuse my horrible illustration skills.

 

that's about it but the engine needs to be at running temp and the wires that are going up the header get hot too
mine gave wild swings, all over the place. but i was happy with how it was so i just put it in a box on the shelf
it was a shitz and giggles project

 

I'm confused. Did it work or not?

 

1. A sniffer probe has the sensor in a compartment that is held in the hand, and a length of metal tubing goes into the test port to get the sample.
This is the modern version of what Yamaha was using at the time (but wayyyy smaller). The handpiece illustrates the type of probe that is used with the XJ test ports.
bacharach-fyrite-intech-co-o2-gas-detector-248511.html

2. What you don't want is for the exhaust to exit entirely freely when testing at the exit of the pipes. The exhaust will be dilluted by the bit of air that is sucked back into the header after the exhaust stroke and cause a false reading. That's why onboard O2 sensors are placed well before the muffler.

 

When inserting that probe does it make an air tight seal?? It seems like that would be important but I could be wrong. Unfortunately, that thing is a little out of my price range. I paid less for one of my first bikes.

Being relatively new to bikes I also forgot about the whole 4 stroke thing and realized air would come right back up the header and mess up the readings.

 

The probe only needs a mostly-tight seal. Back in the olden days of car emissions tesing they used similar probes, and a rag to partially block off the exhaust pipe.

 

Good to know. Thanks

 

I might try a little experiment and find some "sacrificial" headers to make an O2 sensor out of them. The idea is to drill a hole into each header right at the first bend coming out of the engine. I would then install the O2 sensor into each header one at a time and be able to ride the bike and see what's happening as I ride it, tuning as I go along. The question is, would the location of the hole I would drill out be too close to the engine. Does that matter?

 

did you get a O2 sensor yet? there's all kinds but the ones i've seen are just too big to do that. the oem pipes are double wall, that won't make it easier.
you could get a digital tach and tune for max rpm and be done

 

I bought a digital cheap Chinese one off of ebay. I don't want to invest too much into this project. If it works, great. Why would the size of the sensor matter? Why does the double wall matter?

 

when i think O2 sensor, it's the size of one that goes in your chevy. i hope yours is way smaller than that. a oem pipe is double wall, so the real pipe is smaller than what you see, a chevy one would come out the other side of the pipe and block half of the pipe. the oem pipes have a bung in them for a yamaha tester but good luck finding one of those.
when it's all hooked up remember that the 14.7 they talk about isn't what you want to run at, needs to be richer or the engine just won't feel right
a link to the tester you have?

 

I see. Well, it was only $40. Here's the one I got: https://www.ebay.com/itm/52mm-LED-Digital-Racing-Air-Fuel-Ratio-Gauge-With-Narrowband-O2-Oxygen-Sensor/164364589569?ssPageName=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649

For arguments sake, let's just say it does work. What reading should I have? Is placing it right at the top bend a good spot to drill the hole. Would placing just inside the tailpipe work?

 

i hope it does work out.

no idea but it should be richer than what they call perfect.
the top bend? i would think there might still be fire there, that might not matter but on cars it's farther back....?
maybe put the wires in a pipe (1/2 inch copper water pie) with the sensor attached to the end and push it in the muffler as far as it goes, then read it and pull it out and see how hot it got and go from there.
i seem to remember the heater in mine drew some current so keep a eye on battery voltage
i'm going to put some effort in finding mine.
maybe you want a analog meter that won't bounce as much....?

 

So this thread is a bit of a repeat - did @dkavanagh or @mlew get anywhere after this thread:

https://www.xjbikes.com/forums/threads/exhaust-gas-analyzer-for-tuning-mixture.125471/

 

I've been slacking. I'm waiting on parts for the carbs (have them fully apart this time) and will then need to move the O2 sensor idea along to see how it works.

 

I have not got around to it yet. I have all the parts but don't need it yet so its been a project on the back burner. I'll be working on my Venture this winter , hopefully I'll assemble and try it.

 

I'm probably not understanding correctly, but, do any of the gauges shown have probes that will
fit the tapped test holes Yamaha has provided at the bottom of each header ?

 

Not that I know if. I planned to have a fitting screw into the hole in the downpipe and use a weak fan to draw the exhaust gasses down that tube and across the O2 sensor. I'd probably need to try different fan speeds to see what gives the best readings.

 

is there a picture or book on the old yamaha O2 tuner someplace?
i can't see how a sensor could go through a 5mm hole, now it could let exhaust out to go some sort of chamber with a O2 sensor in that
or
a temperature probe would fit in the hole and let you tune EGT the same for all cylinders but nobody knows what that temp should be

 

This link has a photo of the original unit, and maybe the probes laying on top but the resolution makes it hard to see what they are - it appears to measure CO and HC

https://www.xjbikes.com/forums/threads/exhaust-gas-analyzer-for-tuning-mixture.125471/

The chamber idea makes sense to me and dkavanah talked about the adapters in the above thread. He mentions using a fan but I don't see why you would need one as you could just rely on exhaust pressure as long as the sensor is upstream far enough to not give a false reading - a storage chamber could make it a bit easier to place the sensor or just adequate length of tubing on the downstream side.

The other issue is what type of sensor - O2 (narrowband) or A/F (wideband). The wideband would seem like the best choice given that the narrowband tends to indicate either rich or lean because of the steep curve, whereas the wideband sensor can give a direct readout over a larger range, which seems more appropriate to tune an air cooled engine to slightly rich.

The narrow band is by far the simplest, but I am not sure how you ensure the correct temp on either one or say what happens if they are too hot. I bring that up as normally the O2 sensor (750 degrees nominal) or A/F sensor (1200 degrees nominal) are often equipped with internal heaters that are PWM driven based on engine parameters. My limited knowledge I am guessing a direct 12V to the heater would likely be OK, especially if tuning at idle.

 

The probes for the Yamaha unit are the same type as shown in the handheld unit I linked earlier. The sensor is onboard the handle of the probe.
IIRC the Yamaha unit was made by SUN.
They did only measure CO and HC, as that was all that was required at the time. The newer handleld units also measure O2 and NOx (I believe that is correct anyway).

 

Good stuff here - I've used a narrowband lambda on and off (pardon the pun) for years, yes it does switch over right where you want it to have a "slope", but it tells you if your stumble is a rich or weak one. Heater wise just put a 12V supply on it. The wideband is a different kettle of fish altogether, it uses an oxygen "pump" cell to offset the reading, so allowing itself to use oxygen as the read medium - very clever 20 yrs ago, and expensive at the time. Now they are relatively cheap. They do "go off" if they overheat, and I read somewhere (here?) recently that pressure can affect them.
If you common all your headers together, make sure you have enough downstream pipework to prevent negative pulses drawing ambient air in and slewing your readings.

 

I have a wideband sensor on the GS and it's been a major step forward in finally settling the jetting for that bike.
Then again, I'm only tuning one carb...

 

Would anybody know how to hook this darn thing up? The instructions are generic and are just not helpful. I'm completely confused.

 

Looks like this would work as colors match for universal O2 sensor. They really should have included this diagram.



You can verify heater as white to white should be about 4 to 8 ohms

The instructions you posted have the Air/Fuel Ratio Gauge setup fairly clearly, just use the O2 black wire to gauge green for signal.

 

My 1980 (UK) XJ650 has what I believe are OEM header pipes from an American Seca model which have the 6mm dia. bosses welded on for exhaust gas analysis. A friend got a 6mm dia. bolt, drilled a hole in it and welded a compression fitting to it. I length of coiled copper tube was then attached to the fitting. This set up was used in conjunction with the exhaust gas analyser on a dyno machine to check the O2 content at idle. The bike was only idling on three cylinders, #3 cyclinder wasn't getting hot. At idle, the pilot air screws were adjusted to set the carbs. up properly.

This video shows the carbs. being balanced after setting up the air/fuel ratios,

 

Thanks for bringing another step closer. Could you actually tell me how to hook it up? It's still a little unclear for me. For example, according to your diagram it says the two white wires go to "heater", what does that mean? What heater do I hook it up to? Do I even have to connect those? This is still all very confusing.

 

Red and yellow from the gauge to 12V+.
Sensor gray and black from gauge to ground/negative.
Sensor black to green from gauge.

The white wires from the sensor also need 12V+ and ground for the heater. The heater is used to bring the sensor up to operating temperature quickly and ensure it stays hot enough for an accurate reading.

 

THANK YOU!!!!! OMG! So I can put the two white wires on the + side of the battery?

 

Sorry, one white to positive and one white to negative.

 

Just hooked it up and everything turns on! I'll throw the sensor into the tail pipe and see what happens but ultimately I want to find some "sacrificial headers so I can drill holes for the sensor to fit into.

 

Unlikely it will work in the tailpipe, the pulses from the exhaust will draw air back in. You should really drill the collector and live with not knowing which is rich/lean.

 

would this work?
https://www.ebay.com/itm/Gunson-GAS...390219&hash=item3666f2d436:g:uTgAAOSwyNdc6WU7

 

or this
https://www.ebay.com/itm/LPQ-2-Auto...965877?hash=item421ab5d5b5:g:p60AAOSw5-1e6CGp

 

Yes.

And yes.

 

try it on your car

 

Reading the description of that one, it talks about an air pump to draw exhaust gases into the sensor for measurement. That was my plans, so... outstanding, it should work!

 

I'm thinking an aquarium air pump would do the trick. (going to find one that runs on 12 volts)

Ordered: https://www.ebay.com/itm/12V-DC-R38...e=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649

Now, to design and 3d print a chamber that the O2 sensor screws into and has an inlet for the sampling hose and output to the air pump to draw gasses over the sensor. Heat from the sensor is my biggest concern. Maybe plastic will be the prototype of something that can be machined.

 

That's no fun

 

Any chance to see how the dia.bosses are welded on?

 

this is all dependent on a 6mm stud(5mm minor diameter) with a 4mm hole through it. so now the stud has a .5mm wall, it's not very strong.
how much exhaust is going to go through a 4mm hole? enough i hope

 

minnow bucket for fishing uses 12 volt air pumps