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Misc: Everything Else Air Fuel Gauge 02 Sensor Lambda Sensor


Magnetoman

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Coincidentally, I'm working on the jetting for my 'Competition'-model Gold Star. Making a long story short, its GP is now in a box and I replaced it with a 1036 Concentric. Most of the 1000-Series Concentrics, including this one, came configured for 2-strokes, not all of whose features are documented.

Anyway, yesterday morning I did a short loop in the neighborhood and the initial jetting seemed great (at least up to ~40 mph) so I decided it was ready for the air/fuel sensor and data logger. I proceeded slowly with the installation, trying to make sure nothing could fall off, or get caught in the spokes, so this took about 90 min. The photograph shows the final result.

Everything is held in place by nylon straps or zip ties, but I also used blue tape to keep a few things from wiggling. Starting from the back of the bike there's a sealed 12 V battery to power the Innovate LM-1. Next is the inductive clamp around the spark plug lead for determining rpm. Located at the final bend in the downpipe is the wideband sensor. Clamped to the handlebars is the throttle position sensor based on a potentiometer and AA battery. And on top of the headlamp, along with all the extra wire, is the LM-1 and an accessory called the LMA-2 that accepts the input from the inductive clamp along with four additional 0-5 Volt channels. I'm only using one of the channels, for the throttle position sensor.

I hadn't used the LM-1 for quite a while and didn't realize its memory was full. Although I realized much later that the brief message that was displayed upon power-up was for that reason, I was busy getting the bike off the DocZ starter rollers at that point so didn't pay attention to it. I hit 'Record' and, again, didn't notice the absence of an 'R' that flashes every few seconds to confirm recording is actually taking place. If it's actually taking place...

What might be relevant to you is that, although I didn't try to memorize the A/F readings displayed during my ~10-mile ride (because, ahem, the LM-1 was recording everything for me for later viewing...), I did watch them as I rode. The problem of "real time monitoring" this way is the readings are constantly changing, and a digital display is far from ideal under these circumstances. On a perfectly flat road where I could hold the throttle at, say, a constant 1/4 this would be much less of a problem, but on curving roads with hills there's information overload.

Absent data logging, the ideal would be an analog display with variable time constant. Under fairly constant conditions (e.g. flat road at 1/4 throttle) a time constant of 1 sec. would save the rider from trying to mentally average values flickering at 4 Hz throughout the range of say, 13.8 to 14.2, with occasional jumps outside that range. But, when trying to discern transient response (e.g. checking the slide cutaway), a faster response would be needed.

I'm not sure yet whether I'll have a chance for the next run today, or if it will have to wait tomorrow. Meanwhile, I've purged the LM-1's memory of all prior thoughts so it's ready to record.
26805
 

Cyborg

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Good that you posted that. Today is my tax day and any excuse to postpone it is welcome.

Being able to see a 0.3% change in throttle position certainly give you a clear picture.

I have thought about the digital display. Had a discussion a while back about "not" using a digital scale for measuring spring rates and an analog scale is better for the same reason.

I don't think my expectations are too high or unrealistic. I really only hope to get the A/F meter to tell me that I have the correct idle jet and correct main jet. As far as needle/slide etc, I hope that it will give me some sort if indication of whats going on and I may have to combine that with data from the seat of my pants.
The carburetor I ended up choosing is a Mikuni flat slide and it would appear that slide, jet needle and needle jet selections are very limited. I may have to get into linishing the needle and playing with the cutaway or just simply tossing it and going back to the original plan of an older style round slide Mikuni or something that has more options.
 

Robert Watson

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Hi Cyborg.

I have 34mm Flatslides on the Woolly Rapide and Dan has them on his short rod Shadow. Maybe talk to us when you get to jetting, we can put you in the ballpark. (Three sets of pistons got me inside the perimeter fence!)
 

Cyborg

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Thanks,... now I feel totally inadequate now because I chose a 28mm. Actually the plan, mentioned somewhere in that Mongrel thread, was to get the thing running and see if all the madness made sense. If it turned out to be something I want to ride regularly, then I would spend the money for 600cc bits. At this point the intake port is 28, so figured anything much larger was redundant. You'll be happy to know that I was able to bend the tube for my manifold. Used 1.25 stainless with a .065 wall so it makes for a nice smooth transition between carb and port. Filled the tube with cerrobend (in spite of your sensible advice) and stuffed it into the press. I don't have any dies, so just used some sand bags and a 1/2 layer of rubber some alloy bits to spread the force of the ram. Didn't take ay photos, although they would have helped explain things to the coroner had things gone badly.
 

Magnetoman

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I have thought about the digital display.
Going a bit off topic, prompted by an older colleague not realizing his cell phone told him the time, I asked my class how many of them wore watches. I don't remember the number now, but it was only two our three out of the dozen students. I'm sure some of them thought it was an idiotic question given that they never were without their phones, and their phones also told them the correct time.

I wear a watch (because I'm an old guy...) even though I always have my phone with me. I passed through the age of having watches with digital displays when I was young enough that I don't think I could be dismissed as too set in my ways (but, then again, ...) , but I soon went back to analog watches. For the same reason a digital car speedometer is an abomination. A digital fuel gauge could tell me at a given moment the tank is down to 0.24873 capacity, but I don't need that particular information at that resolution so it would be more useful to me to be able to glance at an analog gauge and see the needle is just below the 1/4 mark. Plus, I want that analog gauge to have a time constant of at least 5 sec. because I want it to compute the average fuel level for me rather than telling me all the highs and lows as the fuel sloshes around and forcing me to mentally average it myself.

My LM-1 has two analog outputs (one pre-programmed to output 1-2V for AFR in the range 10-20). I'm tempted to add a small analog panel meter
 

Cyborg

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Perhaps difficult to answer as you are being asked this without knowing background information like my state of mind or IQ, but would it help me if I used an analog meter to read lambda? I could do that while still using the digital gauge. Might help figuring out jet needle position, cutaway etc?

You be happy to know that I avoided those wacky instruments. I'm using the newer Smith's (Digital) chronometric gauges... at least I have the speedo, and think I have a tach on the way after a year of trying to chase it down... speaking of abominations. The distributor has an odd way of doing business.
 

Magnetoman

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would it help me if I used an analog meter to read lambda?
I'm pretty sure it would, but I should be able to answer your question with certainty within a week. A few minutes after my previous post I couldn't stop myself from ordering a meter to connect to my LM-1's analog output.

As the Photoshopped meter shows, even with random excursions outside the range in red it would be a lot easier to mentally average a fluctuating needle to decide the average is ~1 div. to the left of the dark division (i.e. 120 V) than it would be to deal with a digital display updated 4x/second with most values between 110 and 130, but some outside that range.
26810
 

timetraveller

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I'm a bit confuse here chaps. In my car (Toyota Land Cruiser Invincible) I have both an analogue and digital speed display. I use both but more often find myself looking at the digital rather than the analogue. However, neither changes very quickly and I suppose that some sort of smoothing/averaging is taking place on both. It seems to me, without having used these A/F gauges that it is not whether they are analogue or digital which might be problematic but the rapidity of response. Is there a smoothing algorithm built into these wherein the time constant can be altered? To control a fuel injection system a rapid response might be needed but for tuning the various stages of a carburettor my guess is that a one second smoothing might be adequate. Over to you guys.
 

Cyborg

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Welcome to my state of confusion. I would hazard a guess that your changes in speed are more linear than your lambda output voltage, plus the way it receives or displays the signal probably gas some laziness built in, (so all the flashing numbers don't cause seizures). My A/F gauge also reads to 2 decimal points... (paid extra for the second one!). I've since figured out they have a stepper motor series and perhaps that would have been a better choice . This video gives an indication of response time, and actually doesn't look to bad as far as the jumpy digital display thing goes. I have no idea if that light swinging around the perimeter of the gauge serves any useful purpose or it is just supposed to give some sort of value added effect.


 
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Magnetoman

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I have both an analogue and digital speed display. I use both but more often find myself looking at the digital rather than the analogue.
That's an interesting point. I suppose in most cases when you look at a watch you just want a rough idea of the time. However, in most case when you look at the speedometer it's because you want a binary answer. For example, you've just passed a speed limit sign that says 55 and you see a police car. At that point you only care if the number on your speedometer is greater or less than 55. That's something you can process "instantly" without having to compute averages of a string of numbers. Or, even if you don't see a police car, you want to know if you're going "significantly" faster than 55 (obviously, you always will be going too fast, you just don't want to be too far out of line with the limit).

The A/F meter is different in that you would like as much information from it at all times as possible, and it changes much more rapidly than the speedometer does even if you plant your foot on the accelerator or brake. Under circumstances like this, analog is better. Or, at least, I think so.
A/F gauges ... Is there a smoothing algorithm built into these wherein the time constant can be altered?
My LM-1 acquires data at 12 Hz and the settings for the analog output are 'instant', 1/12", 1/6" and 1/3". The 'instant' setting implies that the intrinsic response time of the Bosch sensor and/or LM-1 unit itself is faster than 1/12" but the specifications aren't listed. The digital display refreshes every 1/4" without a way I can see of slowing that down.

There's a limit on how rapid the information can change before it's useless when watched real time. Maybe a time constant of 1" or so would be good. But, imagine burbling along at 25 mph, barely off the idle circuit of the carburetor, then accelerating to 35 to pass someone, and back to 25. To do this a rider grabs a reasonable amount of throttle, so the slide cutaway comes into play for at least part of this, so to know whether the mixture was correct during this "transient" requires data with a resolution more like 1/10". Again, absent data logging, I think analog would be better here. It would be quite helpful just to see if the needle swung toward rich or lean under these circumstances even if things happened too fast to get an actual reading. Yes, a digital display would "swing" one way or the other as well, but it's just harder to assimilate that information. At least, in my experience.
 

Cyborg

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So just maybe the LED's around the perimeter of my gauge might come in handy after all. In any event, I can add the analog meter and have a choice of 3 and see which works best as far as visual perception goes.... assuming thats the correct term.
 
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Cyborg

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So when in doubt, read the instructions.... I went back and had another look at them and the LEDs make more sense now. It would have become more obvious once the gauge was powered up... but anyway.. there are a total of 20 LEDs. 6 are red indicating an AFR between 20.00 to 17.93 15 are yellow indicating 17.92 to 12.98 and 9 green indicating 12.97-10.
 

Magnetoman

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So what kind of AFR range (?) are you looking for??
If exactly the right amount of fuel and air had been mixed in the carburetor (i.e. a stoichiometric mix) and combustion was complete there would be no free oxygen left. With the canonical "gasoline" of yore an AFR of 14.7:1 was stochiometric. However, with pure ethanol it is 9:1, and for in-between mixes the AFR is in-between (e.g. 13.8:1 for 15% ethanol). This would seem to be a problem for using our wideband gauges. But, it's not.

A sensor detects the amount of free oxygen that comes out of the combustion chamber, not the AFR. of whatever goes in. If there is no free oxygen left after combustion that condition is λ=1.00 irrespective of the fuel used. If there is excess oxygen (i.e. the mixture fed to the engine was lean) λ will be greater than 1.0 and if there is unburned fuel (rich) λ will be less than 1.0. Most engines provide maximum power for λ in the range of approximately 0.82-0.88.

For the convenience of people who don't like Greek letters most/many/all of these wideband sensors will multiply λ by 14.7 and display the resulting "AFR" instead of, or along with, λ. For gasoline with fairly low ethanol content the desired range would be ~12-13:1. However, the calculated "AFR" is never anything other than an approximation.

So, to answer Robert's question, you shouldn't be looking for any AFR range at all. You should be looking for a λ range, because λ measures the actual product of the combustion irrespective of the composition of the fuel.
 
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Robert Watson

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With the innovate "sniffer" I asked the Chevy LS hot rod guys next door to me, who of course tune by computer with specific LS programs. They have one guy who is an absolute whiz (and well over the age of 50!) and he reckoned that if we got too close to 12.7 on an air cooled (and fuel cooled) motor we would be asking for trouble for street use. On the first bike we did, a Comet, we were well in the 20's all over to start. We started on the pilot, then the cutaway and finally on the main and got the numbers in the 14-17 range. Gas mileage improved from somewhere very dismal to up over 50 mpg so thought we should leave it there.
Before all this techie stuff I would get a nice tick over idle and then start looking to get mileage in the 50 - 55 range on a nice 65-70 mph 100 mile potter on the local highway.
 

Cyborg

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So what kind of AFR range (?) are you looking for??
Good question, but while I was writing this, Magnetoman replied and saved me.
I was figuring with stoich being 14.7 I would want to be on the fat and happy side of that, with an old school hemi (air cooled) combustion chamber.
 

Cyborg

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That video in post 11 deals with different fuels and says to just forget what is in the tank and still use 14.7
 

bmetcalf

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Gas mileage improved from somewhere very dismal to up over 50 mpg so thought we should leave it there.
Before all this techie stuff I would get a nice tick over idle and then start looking to get mileage in the 50 - 55 range on a nice 65-70 mph 100 mile potter on the local highway.
I assume you mean miles per Imperial gallon, not those undersized US ones?
 

Magnetoman

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start looking to get mileage in the 50 - 55 range on a nice 65-70 mph 100 mile potter on the local highway.
For what it's worth, with the pre-Monobloc carburetor on my 1928 Ariel whose only tuning consisted of polishing the needle on the float so fuel wouldn't leak out of holes on the bottom of the carburetor body, the best mileage I got on the Cannonball was 79.2 miles per U.S. gallon (99 miles per Brexit gallon). Second best was 75.2, and worst were 51.4 and 49.4 mpg, the latter riding into stiff headwinds. I had geared the bike high and kept to a pretty steady 50 mph average.

I started out using the highest octane fuel I could find just to be safe, but in Iowa I was confronted with a pump that had a selection of about a half-dozen ethanol mixes, none with an octane rating listed, plus "normal" 87 octane. I used the 87 and then stuck with it for the rest of the Cannonball because it seemed to be fine.

That video in post 11 deals with different fuels and says to just forget what is in the tank and still use 14.7
That advice is completely wrong for the reasons I gave in my previous post.
 

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