This is the steering head nut that fastens the front forks in to the frame.
Regular maintenance calls for the steering head bearings to be lubricated and this item should be replaced at the same time if corroded or damaged.
Correct for 78-85 model ATC70 but also can be used on 73-74.
Suits ATC70 78-85, ATC90 74-78, ATC110 79-85, ATC125M 84-87, ATC185/S 80-83, ATC200 81-83, ATC200E/ES 82-84, ATC200M/S 84-86
Also suits Z50A 68-78, Z50R 79-98, CL70 69-73, CT70 all, CT70H 70-73, SL70 71-73, XL70 74-76, XL75 77-79, XR75 73-78, XR80 79-84, XL80S 80-85,
