Lambda sensor on KZ, Super Shifter, Does it work?

Anyone with experience using a Lambda sensor on a KZ or Super Shifter? Does it really help tuning the carburetor? Does the sensor crack the exhaust pipe, I’ve read some comments where they talk about that, cracking the exhaust pipe? Is it reliable a Lambda sensor on a KZ?
I currently have an EGT sensor and it’s Ok but not so precise, so I wonder if a Lambda sensor would be better, more precise, easier to read in order to fine-tune the carburetor.
Anyone has any experience with the Supa-Tuna from Australia?
Thanks in advance.

I don’t know much about the specifics of using a lambda sensor on a KZ, but I have tuned with lambda sensors on other engines and can give you the following advice:

  1. A four-wire or five-wire “wideband” sensor as used on most passenger cars these days can tell you more accurately how rich or lean you are, while a one-or-two-wire sensor will only tell you “rich” or “lean” and then you have to work out from your other data when that transition is happening

  2. Lead fouls and destroys oxygen sensors, and the better the sensor the more sensitive it is. Use pump gasoline, and stay with it afterwards.

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Thanks Charles, I did read about using pump gasoline being better, but some people have mentioned that a Lambda sensor won’t work on a two-stroke engine due to timing ignition and a few other things, I hope someone else offers more information, if it does work on a KZ then it should be much precise and better for adjusting the carburetor than an EGT.

In a strict sense the sensor will “work”, you’ll get accurate readings… in the case of leaded fuel only for a certain time.

My understanding is that the challenge is getting useful\actionable data from it. Due to how the exhaust pulses and cylinder fill varies, it’s difficult to get good insights. It seems to work better as a way to read the AFR once the engine is tuned, vs using AFR to tune it.

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tell me where you get this idea that the EGT is not accurate enough! In my experience, it’s a godsend! The EGT gives fast and accurate readings, across the whole RPM range. I don’t know exactly, but I think the response time is within maybe 2 seconds. I’ve never used a lambda device,so I can’t speak to its usefulness, but I find it hard to believe it could be better than the EGT.

perhaps you could explain to me what you believe to be the shortcomings of tthe EGT?

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Hi, I don’t think there’s anything wrong with an EGT, I use it all the time and it works very well, although no one has ever told me what’s the maximum EGT that you can have without blowing the engine?
Here in Europe, when it comes to KZ engines they tell you to keep it below 680 degrees Celsius, although I driven with an EGT of 685 degrees Celsius and had no problems, so I don’t know if you know what’s the border line EGT that you can have on a KZ engine (TM R1)?
However, I do hear some people talking about lambda sensors being more precise, in order words, a lambda sensor should read between 0.85-0.90 for an engine to run perfectly, whether that is true I don’t know… so I wonder if anyone has ever used a Lambda sensor on a KZ or any two-stroke engine.

What’s great about the EGT is, the reading will go up to the point you get detonation, and then it will drop. At the end of the straight, look for the highest EGT you can. Coming out of the corner, look for the highest EGT can get. It will be lower on the low end. Detonation is caused by excessive heat and/or pressure. On the low end, near peak torque, the pressure is at its highest. You need to keep the heat down to prevent detonation. 200° F, plus or minus a little, lower on the low end, is not unusual. In any case, whenever you see a low temp, enrich the mixture first, if it goes down further, then you can then lean it down.

I’ve been a big advocate of the EGT since I built my dyno in 1985. I count it as the best tuning device ever!! Unfortunately, many In an in and in and in and in a little and in and I know what I read what the answer you soon wantingpeople, like yourself, are not fully aware of how to use it.

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Is there a maximum EGT number that you can give me for a two-stroke engine, approximately?
You’re not telling me to push and wait for detonation to occur and then I’ll know that’s the limit? That would be too risky…

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I’ve been karting for 55 years, I have a very good reputation, you think I would risk that by giving you bad information??
Long story; my driver, who I told the same thing I told you, was leading the pack of sit up Sprint’s Sears point Raceway. Watching the EGT, he observed it to be reading 1050°. As he told me after the race “I thought to myself, I can run hotter than that!” He leaned it down. As we were observing from the pits, he suddenly lost the lead and fell back, quite a ways. Imagine our disappointment. As the pack came around on the next lap, he was back in the lead. After the race to explain; “it was reading 1050° and I was thinking, I can run that EGT higher than that, so I leaned it down, just a little” “well, the EGT dropped to 950° and I started slowing down”. It happened just exactly like I told him it would! By the way, this was with a KT100 with a pipe.

EGT readings will vary with the weather. On cold days, your engine can get rid of more heat, so you can run leaner, higher EGT. On hot days just the opposite. Air density makes a difference! You do have an air density gauge right? I guess you just have to believe me!!

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I believe you, I’ve seen a number of your posts and I know you’re a knowledgeable guy with tons of experience.
I’ve read about an air density gouge but I’ve never used it (you know how it is when you have a team working for you, you focus on the driving and the races and not so much on everything else) but I’m gonna get one of those, so thanks for the tip… now what reading should I expect during the cold days vs the hot days, how do you rely on the information that you get from the air density gouge? I guess if you get an X reading you go leaner, and if you get a Y reading you go reach, so the question is, what’s the X and Y number that you look for from the air density gouge?
Thanks in advance :pray:
Ps by the way, 1050 degrees would be about 550 Celsius, that would be considered a very low EGT on the engines that I’m familiar with (Iame X30, Rotax Max, KZ) normally we aim for 650 Celsius, about 1200 Fahrenheit)
I just remembered, there is an App for the phone that you can download and it works by getting the information from the internet, the App tells you the temperature, air density, altitude… and then it calculates the main jet that you should use if you have a Dellorto carburetor , I don’t know if there is an App similar to that one for carburetors like the Tillotson?

I’ve seen 1200 in the dyno room, race gas, KT100, but that’s the highest. Most are between 11 to 1150. The KT100 in my story was racing with regular gas on a cool day, no sunshine. Compression pressure, ambient temperatures and pressures, fuel, compression ratios, cooling (air or water), they all make a difference.

On that day when you’re running your best, observe the air density, your jettings and anything else you feel that is important and use that as your base criteria.

Another driver that I trained in the use of the EGT. Were sitting in the pits in his engine builder came by requesting to look at the spark plug. He had a look of amazement on his face after seeing the spark plug. “That’s way too lean” he said. Me and my friend just look at the and laughed. It was a regional race in Southern California. Lots of big-time competition. My friend had fast time and won first place Winning all his heats.


Al I think he’s just clarifying vs accusing you of anything.

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