There's a thread in here somewhere where someone pointed out how to ID all the casting markings and differences between 85 and 86 ATC250R and 86-89 TRX250R cylinders and heads. I'll post of I can find it but here's a free bump for someone else to chime in
The 88/89 had a really small dome, 87 was a little larger and the 85/86 had the largest one.
The HA2 is trike only that’s why I’m at a loss was It maybe a race head sold through Honda ?
No, the 85 and 86 ATC250R AND the 86, 87 TRX250R ALL had "HA2" in the middle of the part number.
The 88 and 89 TRX250R, on the other hand, had "HB9" in the middle of the cylinder head part number.
I looked it up on the Honda OEM parts fiche to be sure.