Why the cylinder head seal design?

I remember doing a 16K service myself a while ago and noticed that the seals for the cylinder cover aren't just a rectangle rubber seal. They also have half-circles as illustrated below:



Would anyone know the particular reason for having half-circles in the seals? Why not just take out the half-circles and have just a seal going around the cylinder head?

One theory is that the half-circles are there to keep the seal from moving around. Another theory is that it provides room for expansion so that when the engine gets hot the metals expand and having the half-circle there allows the seals to bleed into the half-circle area instead of bursting.

Those are all theories though and would be great if I had something more solid like a fellow Honda engineer chiming in this board.

 

The cutouts in the head on some bikes are an aid in cam removal. Dunno for sure about the VFR, but I would lean in that direction.

 

well a square is much harder to cast but I ordered mine with rectangles and it allows a slick50 fitting in case you run low,,,,,

 

i think they're necessary during engine build machining to line-bore the cam journals.......?

 

Interesting, I didn't know that was the purpose for other bikes.

Gotcha, thanks for your engineering perspective! Oh, and Georgia ain't exactly all sunshine right now. This morning I before I left for work I toggled the temperature gauge and saw 39 degrees. Yep, it's cold and thin sheets of ice on cars outside reinforces that fact

I haven't done any recreational riding for the past 3-4 weeks and I'm starting to go batty. I've got some video games to kill time but there's nothing like hitting the redline and getting the knee out!

 

My thoughts exactly.