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Discussion Starter · #1 ·
Hello,
Im changing exhaust in my r125 (21’) but it dont have any space to plug in lambda. I cant find any emulator that fits neither measurements/dimensions so i could weld in the thread to lambda. Only i could fine are emulators and measurements of 05-13 or 15-18. Someone could help?
Greetings
 

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2008 YZF-R125 (180cc)
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maybe add a picture of the lambda probe you have?

Does your exhaust have any hole at all for a lambda (even if it's the wrong size)?

Normal o2 sensor bungs have a thread whcih is M18 x 1.5, so I wonder if you could weld on a threaded bung for a normal o2 sensor (e.g. O2 Oxygen Sensor Boss M18 x 1.5 Stainless Steel Weld On Bung Plug Nut Cap Kit | eBay ) and then find/make an adapter to fit yours?

I had to add a sensor to my exhaust (gen1) for my autotune and found the metal of my exhaust very thin so it was quite difficult to weld, even with TIG.
 

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Discussion Starter · #3 ·
maybe add a picture of the lambda probe you have?

Does your exhaust have any hole at all for a lambda (even if it's the wrong size)?

Normal o2 sensor bungs have a thread whcih is M18 x 1.5, so I wonder if you could weld on a threaded bung for a normal o2 sensor (e.g. O2 Oxygen Sensor Boss M18 x 1.5 Stainless Steel Weld On Bung Plug Nut Cap Kit | eBay ) and then find/make an adapter to fit yours?

I had to add a sensor to my exhaust (gen1) for my autotune and found the metal of my exhaust very thin so it was quite difficult to weld, even with TIG.
here are the pics. And i just CANT unscrew it
Tire Wheel Automotive tire Tread Synthetic rubber

Automotive fuel system Automotive tire Motor vehicle Automotive exterior Gas

Automotive tire Motor vehicle Automotive design Rim Bumper

Tire Wheel Automotive tire Tread Synthetic rubber
 

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oh right, that looks like a normal sized o2 sensor from the pics. I guess it would be a 22mm spanner if so (I think). Or is it smaller?

They do get seized pretty badly. I rounded off a set of the hex faces on my wideband getting it off this last time, not great. You can break the end (cable etc) off the o2 sensor and get a socket on there if it's a narrowband since they're cheaper to replace but if it's a working wideband they're £~100 to buy so would really rather reuse if possible. I resorted to heating the pipe around it, lots of wd40 and a long bar over the end of my spanner but then it came loose thankfully.

If you're getting a new exhaust could you just get a new sensor too so you don't need to unscrew it?
 

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Discussion Starter · #5 ·
oh right, that looks like a normal sized o2 sensor from the pics. I guess it would be a 22mm spanner if so (I think). Or is it smaller?

They do get seized pretty badly. I rounded off a set of the hex faces on my wideband getting it off this last time, not great. You can break the end (cable etc) off the o2 sensor and get a socket on there if it's a narrowband since they're cheaper to replace but if it's a working wideband they're £~100 to buy so would really rather reuse if possible. I resorted to heating the pipe around it, lots of wd40 and a long bar over the end of my spanner but then it came loose thankfully.

If you're getting a new exhaust could you just get a new sensor too so you don't need to unscrew it?
Good idea but idk which lambda will fit my electrical connector
 

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When I changed the exhaust on my 2021 model ( 2021 EU5 model ) this was not a problem at all. The Shark system had a thread for the lambda sensor and an adapter to reduce it to the smaller probe thread was included. The only thing I did was to shorten this adapter a little bit, so that it don´t stick that deep in the exhaust hose.
Also unthighting the lamda sensor was easy and I needed no enrome force to do it.

If you remove the lambda sensor I´m very sure that you will get in trouble.
The emulators that you usually can find are designed to work for monitor lambda sensors after the catalyst in cars. They shall avoid that in case the catalyst is removed the MIL in the dash will be lit. But in your case this is the lambda sensor that is upstream the catalyst and it controls closed loop the mixture.
 
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Good idea but idk which lambda will fit my electrical connector
I meant get one from yamaha if they're not too expensive... they will know which one fits. You may end up wrecking the existing one trying to get it out anyway so might be better to leave it in place.
 

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Discussion Starter · #8 ·
so What size is that??
 

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hmm right that def looks to be the smaller type. I just searched quickly to see what a replacement sensor costs and found this page:

..where they mention sensors in two sizes - M18 and M12... which looks to confirm your measurements.


So If I understand the situation correctly, you have a '21 bike with a M12 O2 sensor and you new exhaust doesn't have an O2 sensor hole at all, but the weld-in bungs are M18 only, not the smaller M12 size. Correct?

In which case I think you could (TIG) weld in a regular M18 sized o2 sensor bung on your new exhaust, and then use an adapter like this to fit your M12 sensor:

https://www.ebay.co.uk/itm/293933242332

From the pics it looks like you got the sensor out in the end (congrats, hopefully without damage) so I guess at least you can just transfer it rather than needing to buy another, since they look to be $100+ (based off the magnum tuning page)..
 

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It´s exactly the same adaptor that came with my exhaust. I only did schorten it a little bit. The only thing you might need in addition is a M18 copper washer.

Automotive tire Synthetic rubber Tire Wood Tints and shades
 
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Hello,
Im changing exhaust in my r125 (21’) but it dont have any space to plug in lambda. I cant find any emulator that fits neither measurements/dimensions so i could weld in the thread to lambda. Only i could fine are emulators and measurements of 05-13 or 15-18. Someone could help?
Greetings
I have just bought a Black widow exhaust for mine(2019), it has a hole on the right hand side. Cheak that the exhaust you bought is compatible.
 
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