I had in mind to make the mating surface on top case smoother, free from scratches. I found that the surface need some grinding to be completely flat so I can trust an RCS base gasket to seal. No grinding, sure oil leak.
-No grinding and flat surface, no RCS gasket. This gasket does not like sealer, the viton rubber need to be mounted dry.
It has worked well all years with std fiber base gasket. Now next level with steel gaskets that need no additional tightening torque or re-torque afterwards.
I hope 20ft lbs will be enough. I usually apply 28Nm, (20.65 ft lbs)
Cyl block is new with virgin surfaces. It has fat sleeves that need extra space that opened some additional ports
A real milling machine could have done it more beautiful, but one case stud did not want to move. So the manual way...
Below first and last photo after 1-2 rounds with grit 240, maybe 1 round of 400 too. I found that more rounds with 240 was needed. Middle photo almost Ok. 1 round more with grit 240 + finishing 400 to ensure smooth surface. I need to tape the surface to avoid scratches when cleaning the case from all burrs and dirt, outside as well as inside.
The lower surface is cyl 3 front side, the area between tha cam chain tunnel and oil return 3-4
Edit: last photo show the initial bad surface. I compressed the other photo too much
Each round i= 2 sanding papers glued (spray glue, removed with acetone when papers are teared off) and taped on plywood clamped on a small table. so far 10 papers of grit 240 + 2 400.
I used same method for the head and 836 cyl when the restore started 2012. That time kitchen table... It works
