i have a 1980 atc 110...i think my engine is not the stock 1980...i think now i have a 82 83 engine..how i can make the difference.i say that because i want to change the spark plug ...i found a ngk br7hs...i think is not the right one..1980 need a d8ha and 1982 1983 dr8sh.my tread size is 14 mm .thanks.