Drop in afr on every pull.

Yamarace998

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Location
Mo i Rana
Country
Norway
Snowmobile
Yamaha nypex mcx 400
I started to notice in logs that the afr drops to arround 10 in afr on every pull at arround 7000rpm. Turbo dynamics tuned. Anybody else see this? Is it normal?

IMG_3880.png
 
What year is your sled ?
 
Looking at the log you are at 60% throttle there and whacking it quick. It needs fuel to accelerate the engine. It leans back out once it’s thru that phase. Totally normal. If it didn’t richen up it wouldn’t rip up thru there and would be too lean and you’d have a lean pop.
 
Ok:) i can also sometimes see a black stripe in the snow, 2-3 meters long there the sled start to gain rpm.
 

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Here's one of mine. Drops to 10 at 7000ish rpm.
Screenshot_20240312_164114_Gap Flasher.jpg
 


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