Lifan Greyhound Model 66015 engine part info needed

#1
Moving my engine I managed to brake off the oil fill plug for my Lifan Greyhound 6.5 HP engine model 66015. The H.F Predator oil cap/stick does not fit. I ordered a pack of five from China that are supposed to fit, and they too do not fit. The threads/pitch are wrong and bind at the first thread.
Anyone know what size oil fill plug this engine takes? I have nothing metric that large to verify what size it may be.
 
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