Misc: Everything Else Air Fuel Gauge 02 Sensor Lambda Sensor

Magnetoman

Well Known and Active Forum User
VOC Member
if the sensor maxes out at 5V, then why does the AFR go over 20?
You're mixing units. The voltage signal from the sensor isn't itself relevant because it's translated by the LM-1 into the AFR number it displays. In principle a sensor that provided an output that went from 0 to 357 Volts, or -27.2 to +45.3 Volts, could be mapped into numbers that ranged from, say, 9 to 20.

I made a bit of progress on my jetting this morning. I found that turning the pilot mixture screw all the way in had no effect on the rpm. The last time I had that problem, coincidentally on a different Gold Star but with a Monobloc, I found the float level was very low. So, although I checked it long ago, it's time to check the float level again. Well, not quite time. We're having a birthday brunch for my older daughter in 45 min. so it will have to wait until later.

With the pilot screw all the way in I made another 8-mile run. Halfway through the run, when the engine was fully up to temperature, I stopped and watched the AFR as I adjusted the pilot screw. It got richer as I backed it out a half turn, and got leaner as I turned it back in, so all the way in was leaner than yesterday (but still not correct). Anyway, with the somewhat leaner pilot mixture the bike behaved better than yesterday. The mixture was still too rich but it never dropped below 10 where igniting it seems to be problematic.

The DocZ rollers are earning their keep. Bikes like rich mixtures to start and my Amal 1036 doesn't have a choke. But, that's no problem with rollers. One problem I am having, though, is I'm way too used to the up-for-down shift pattern of my other Gold Stars. This one has rear sets, but not a reverse cam plate, so it has a Triumph-like up-for-up shift pattern.
 

Cyborg

Well Known and Active Forum User
VOC Member
Been hiding out in the Channel Islands , so preoccupied with other things for a couple of days... Saw my first giant sea cucumber today.... interesting method of eating those critters have. Helps put dinner at the in-laws into perspective.

Anyway....It was the info that came with the A/F gauge that had me wondering. The voltage maxes out at 5v and the gauge maxes out at 20, so assumed the graph would max out at 20 as well.

How is your jetting session coming along? Btw, I looked up DocZ... I’m envious.

Back to Oldhaven’s question about the gauge displaying lambda. The fellow at the factory got back to me. It turns out that the answer is yes. Apparently underneath the sticker (photo post 41) there are two switches, and you just have to flip switch 2. He did say that the switches are very tiny and easily broken, so he recommended just leaving it as is. They do sell them preset to lambda. Not sure if the switches are any different than normal, or it was just a polite way of telling me that he thinks we’re all lumberjacks here in B.C. and too hamfisted to flip a switch without mangling it...... or he would prefer I bought another gauge. I do have to say, he has been quick to reply and seems genuinely happy to answer questions, so that’s refreshing.
 

Magnetoman

Well Known and Active Forum User
VOC Member
Been hiding out in the Channel Islands ,
Guernsey and Jersey? Santa Catalina and San Clemente? Newfoundland and Prince Edward?

How is your jetting session coming along? Btw, I looked up DocZ... I’m envious.
The DocZ is a leg saver, if not life saver. There's nothing like it, especially when sorting out jetting.

On the subject of jetting, a few test runs had it behaving like the Monobloc on my Catalina (nb. not Santa Catalina) had, where I found the level in the float bowl very low. So I measured the level and found it very low. Unfortunately, my Concentric box only contains three floats, all of the original 50-year old plastic kind. All are slightly distorted. Although I know how to move the seat to adjust the level that way, instead I decided to order an adjustable 'stay-up' float that's due on Wednesday. Meanwhile, I used the break to get back to the flow bench to characterize the pilot circuit.
 

Cyborg

Well Known and Active Forum User
VOC Member
At the moment.... in the Salish Sea “Channel Islands” would be misleading I suppose. They are actually referred to as the gulf islands, but are in the Straight of Georgia that is called the Salish Sea by BC’s indigenous folk. What do I know.. I’m a former flatlander and it looks more like a channel to me.
 
Last edited:

JustPlainBill0

Forum User
Non-VOC Member
I'm not sure this will be of any value to this discussion, but I replaced my Rapide's Amal carbs with Taiwan versions of Keihin PWK 30mm carbs and have been using an AEM AFR meter to adjust the carbs - at least idle and up to quarter throttle. (My Rapide is not roadworthy now and further tuning will have to wait until it is.)

What might be helpful in a general (practical?) sense, is a video I made of the tools, set up, equipment and procedure I'm using in this endeavor:


I'm using two cameras in the video, one to record my activities and one to record the AFR meter and tachometer. The second camera serves as my data logger; and should be especially helpful when I do get the Rapide on the road.

There is very little technical information in the video, but the last two minutes consists of a demonstration of synchronizing the carbs and adjusting the pilot circuit - with the AFR meter video inset into the main picture to allow viewers to watch the AFR reading changing as the adjustments are made.

Bill
 

Cyborg

Well Known and Active Forum User
VOC Member
Welcome to the forum and welcome to this thread.

As mentioned previously in this thread, my instructions also say to mount the bung at least 18" from the port, but it goes on to say "if you expect EGT over 800 C". I'm still thinking that less than 18 is ok if Ducati can do it. Farther from the tail pipe would be good in my case because I'm using a relatively short reverse cone setup.

Can't say I'm in the mood to buy another (EGT) gauge after my recent fiasco with "Smiths" or should I say "the Smiths"..as in plural.
 

JustPlainBill0

Forum User
Non-VOC Member
Thanks for the welcome Cyborg. This has been a very informative and entertaining thread, but after having watched a video today titled "Do You Want A Lean OR Rich AFR? | Fueling VS Power! [FREE LESSON]" by a New Zealand outfit called High Performance Academy, I'm afraid the thread might fall into the category of over thinking the problem. The presenter (Andre) starts off making the point that while a 14.7 AFR (stochiometric) might be ideal for power and fuel economy, a richer fuel mixture provides more fuel to mix with the air, helps burn all the oxygen and therefore, obtain all the power possible from the engine. Furthermore, it aids cylinder cooling and ultimately prolongs engine life. His next point, and what the remaining 13 minutes of the video demonstrates using a dynomometer, is that fairly significant changes in AFR (or Lambda) do not make correspondingly significant changes in power from the engine. I do not use Lambda, but I do understand that when one varies the AFR by about 10% (from Lambda 0.87 to 0.97) and the torque curve is basically unchanged (with otherwise identical conditions), there might be more value in getting our AFR values to the "good enough for government work" stage, than obsessing over the process. Though Andre's conclusion that running a richer fuel mix to get the same power is better for the reasons listed above, is a good one too.

I have been using the AFR recommendations I found on this Harley site: http://www.nightrider.com/biketech/Pro_tuning.htm to tune my Rapide.

Operating Mode
Cold Start
Idle
Part Throttle Cruise
Wide Open Throttle
Performance Engine
12.5 -11.5
During engine warm up
13.5 - 12.8
14.0 - 13.0
12.8 - 12.5
Values as rich as 11.5 can be used to reduce detonation
Pollution Controlled Vehicles
12.5
14.6
14.6
13.8 - 12.5


Oh yeah, a link to the HP Academy video:


Bill
 

Cyborg

Well Known and Active Forum User
VOC Member
I haven't viewed the video yet, just taking a break from putting the roof on the apprentices playhouse. I haven't used an AF gauge before, but don't think my expectations are unrealistic. Just expecting it to tell me whats going on and final settings will be based on drivability not the gauge... and maybe a peek at the plug because the fuel we get here is still relatively normal. To me its just another tool and don't see myself chasing a specific number. Actually for street riding, I look at a dyno the same way. It can tell the operator some extremely useful information, but how the bike behaves on a dyno may or may not tell you how it is going to operate in the real world and may still require some tweaking. Later this month I'm scheduled to do some farting around with A/F sensors and data acquisition/logging, so that may alter my expectations slightly. They have a dyno there, but unfortunately it's not really motorcycle friendly.


EDIT: watched the video and didn't see anything that would cause me to change my point of view or see any surprises unless I'm missing something. Slightly different ball game with programable ECUs, modern combustion chambers and fuel injection. As for over thinking the problem, I suppose that depends on your perspective and you certainly wouldn't be alone in that camp. There is no doubt one can jet a carburetor without any fancy gismos, but no regrets so far as I'm having fun learning.
 
Last edited:

Magnetoman

Well Known and Active Forum User
VOC Member
Slightly different ball game with programable ECUs, modern combustion chambers and fuel injection.
I'm afraid the thread might fall into the category of over thinking the problem.
It might count as overthinking the problem if our bikes had fuel injection and programmable ECUs where we could input our desired AFR and let the ECU take care of giving that to us to within 0.1 at all rpm. Unfortunately, we have Amal carburetors where we have to manually adjust the pilot mixture screw, slide cutaway, needle jet, needle notch, and main jet to give AFRs approximating what we want across all throttle settings. So, no, this thread isn't overthinking the problem.
 

Cyborg

Well Known and Active Forum User
VOC Member
Correction..... you have an Amal.... I have a Mikuni Flat Slide

We need an emoji with a smug look on his face and an aura of superiority.

(I have a feeling that will come back to haunt me)
 
Top