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What to do with O2 sensor on WR250R?

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Hi Guys just after some info on what to do with the oxygen sensor that I have removed when installing the Q4 fmf slip on. I have the Australian model WR250R, which does have an O2 sensor on the stock pipe but no where to put it on the fmf pipe. What are the consequences of running the bike without it? Cheers

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Hi Guys just after some info on what to do with the oxygen sensor that I have removed when installing the Q4 fmf slip on. I have the Australian model WR250R, which does have an O2 sensor on the stock pipe but no where to put it on the fmf pipe. What are the consequences of running the bike without it? Cheers

The only consequence that I can think of is.... you will have to install a programmer asap

I am from Singapore, and we have the Euro spec WR too...

Just tug that plug under the seat and leave the O2 sensor attached to the stock pipe... no error code will be thrown

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It really depends on what the O2 sensors purpose is, if it actually monitors a/f ratio and the computer adjusts on the fly (closed loop) then removing it will cause limp in mode (constant open loop), which most likely is a base set of parameters. If that is not the purpose of the sensor I dont know why it is there. On a car no/faulty O2 sensor throws a check engine light and terrible fuel economy along with a plugged catalytic converter.

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That's what I thought so I wasn't the brave one to take this step first...

I was the fifth actually :)

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I had the problem/question a couple of weeks ago when I went to put on my Q4. I disconnected the O2 sensor and didn't get any faults on display, and have noticed a nice performance increase with the Q4. So at this stage I am running without the O2 Sensor.

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Does anyone have a link to a pdf of the Euro model service manual? Or can someone post the pages in the manual where it is mentioned? There is no mention of the O2 sensor in the US manual except for showing it in the wiring diagram. I am surprised it does not throw a code when disconnected and was wondering how Yamaha is using it in the system.

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As suggested I am in the process of having a threaded fitting welded to the muffler to allow the O2 Sensor to be fitted. I would suggest that it would make sense to have it fitted as the after market Australian Yamaha Pipe has a fitting for the O2 sensor. I will post with images/results after the modification.

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I got my FMF Q4 & Powerbomb last night. I also have the 02 sensor on a euro bike. For now I have disconnected the O2 sensor and WOW it flys. Power wheelies in second without the use of the clutch. Couldn't do that before.

I am however, going to get a bung welded in with a plug, so I can test with and without the O2 sensor. I will post my results to this thread when I get it done.

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Only completed a small ride so far and seems to perform quite well, very hard to quantify and specific difference. I will do a long ride this weekend to access what effect the o2 has on the fuel economy.

I am very happy with the performance increase with the addition of the new pipe, just like having a new bike....

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Just found this thread. Barrett's make a very nice pipe for the WRR which comes with a bung for the O2 sensor. Just received mine and am putting it on next week so will post any comparisons.

 

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