Thanks Dan, I just bought two HF 2.5 hp engines from dirt cheap and one needs a plug. I paid $42 for the first one and $32 for the second one. I just couldn't walk away from that one. Looks like i have some bike building to do.
Still looking Elmo, but found these, Scooter Spark Plug E6TC The scary part is these are said to be for 2 smokes? Does it matter? The plug off my HF is a E6TC
Found it. NGK would be BKUR6ET and champion would be; KY7YKJCR. HF manual says gap is 0.027” to 0.031