:dunno:On my 75 2F I have 2 striped threads both on the head and bolts for the exhaust and intake. They are the 2 outside ( 1 at the rear and 1 at the front of the motor) bolts. These 2 are different sizes than the otherbolts and studs. Anyone know what size they are? I need to retap or heli coil them. I am trying to figure out what size. 10 or 11 mm and what pitch 1.25 or 1.5 or what? Their is not enough thread on the head to get an accurate reading and the previous owner used the wrong bolts so they are know help. Why can't these darn bolts be consistent.... ???