04-14-2020, 05:08 AM
I think Honda phased out JIS screws 20 years ago or more, although there may be some electrical sub-assemblies that have them, and on carbs. I remember back in the points and condensor days, JIS screws holding them on had a different thread pitch, so lots of points plates got stripped as a result.
Countersunk screw heads like the 4mm ones on master cylinder caps are hard to loosen because they have a lot of surface contact area (and friction) under the head, and are prone to corrosion. A cross (+) is used in that application so that the 4mm threads aren't easily snapped off, as if it would be with a hex bolt or hex socket head. When removing master cylinder covers, I usually just grab the hand impact driver and give it a light tap to break it free, never fails.
Countersunk screw heads like the 4mm ones on master cylinder caps are hard to loosen because they have a lot of surface contact area (and friction) under the head, and are prone to corrosion. A cross (+) is used in that application so that the 4mm threads aren't easily snapped off, as if it would be with a hex bolt or hex socket head. When removing master cylinder covers, I usually just grab the hand impact driver and give it a light tap to break it free, never fails.