I'm thinking you running with the choke on might have richened the mixture enough to get some unburnt fuel in your exhaust. Which then ignited unexpectedly. How's your carb setup in general?
"Stay the Trail," "Tread Lightly," and "Leave No Trace" ethics
Rising Sun Bio
2F "Brahma" + Lockright, tach, Warn 8274, FJ60 Power Steering,
soon to lose the Sanden OBA
to go back to factory emissions
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Up next: Something that makes a funny whistling noise...