Wr250f decell backfire

A.G130
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A.G130
I have a 2020 wr250f with a full GYTRns-4 system and has heaps of decell backfire under decell if I run standard map or any of the other popular maps. I currently am running a very Rich mapping to stop this but feels like I have really dulled the power . Has anyone else experienced this problem with an aftermarket exhaust.
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Paw Paw 271
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Paw Paw 271 2/26/2021 1:40pm
2/26/2021 1:40pm Edited Date/Time 2/26/2021 1:41pm
Did you replace the exhaust gasket at the head on the pipe when it was installed? They are to be used only once. If not is will leak and cause a very lean condition in the pipe and will cause the popping you are hearing.

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kb228
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kb228 2/26/2021 4:04pm
2/26/2021 4:04pm
In addition to pawpaw.. having a rich map will let too much in and it will ignite in the exhaust
A.G130
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A.G130 2/26/2021 8:20pm
2/26/2021 8:20pm
Running 98 Ron pump fuel in it. I had the bike shop install exhaust when I bought it new so unsure of bthe exhaust gasket might buy a new one next week and try it also

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PMR 3
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PMR 3 2/27/2021 1:04am
2/27/2021 1:04am
Hopefully you figure it out between the gas, gasket and/or map. A friends bike would pop on decell if there was any leak in the head pipe, mid pipe or muffler. Maybe check it out, the air boot & box also?
blaze 57
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blaze 57 2/27/2021 11:14am
2/27/2021 11:14am Edited Date/Time 2/27/2021 11:18am
I had that same issue on my WR 450 and mapping would not solve it. I had to take it into the Yamaha dealer and they used their diagnostic tool to change the CO setting.

My issue was popping going downhill and once they changed the CO setting it made the popping stop and also made it easier to start. Their Yamaha tool they used changes the setting from 0-2000 rpm and mapping only effect from 2000 or 3000 rpm and on I think.

So in the end they made it richer from 0 to 2000 rpm. All the 2012 wr 450's had this same issue from the factory and got worse once you placed to FMF pipe on it or leaned it out.
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A.G130
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A.G130 3/4/2021 3:44am
3/4/2021 3:44am
Yep it was the co sensor I talked to the local Yamaha dealer and they said it's a factory fault in some of the the 2020 wr250f they went 10% richer from the 0-2000rpm range and it's completely fixed. No backfire today even when I was running the Keefer map, even starts way better then it used to.
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