A complany called INOVATE make an after market AFR meter.
We use them to check AFR on cars when bolting on big turbos and upping boost or installing new computers to make sure they are safe to drive to the dyno to be tuned on the rollers


These work the same a std dyno AFR. A sensor that is screwed in a 1" pipe that is clamped into the end of the exh pipe.
Plugged into a lap top you get real time graphs. Can play back and save ect

We usually clamp it in, run the cable into the car, and head to the highway and tune on the run

But on a 2-stoke, yeah, can get a bit gummed up with oil.

http://www.rocketindustries.com.au/search.php?brand=Innovate&menu=Tools+%26amp%3B+Shop+Equip.

This is the AUST supplier for them.
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