Topic: CB750 experts, what are these holes in the crankcase for?

[markb]

I posted this same question on my restoration thread but came up empty.  I’m trying to figure out what the holes in this picture of the forward part of the clutch area are for.  The horizontal hole goes through to the inside of the case.


Here’s a shot from the bottom and you can see that the vertical hole comes all the way through to the bottom and passes through the horizontal hole.  This is on my early sandcast.


Wierder yet, in this pic of my later sandcast, the vertical hold does not go all the way through.  I'm stumped.  Anyone have an explanation?

[Magpie]

Hi Mark! This is a repair in the clutch area of engine #260 as well so it may have been an early casting/machining problem. Cliff.

[754]

I am not certain where you mean, is pic taken thru the sump?

 You do know that the cases changed after # 219 do you not?

 I took a look thru my parts book but was looking in the wrong area I think?

[markb]

Here's a wider angle to help you get your bearings.  It's in the front area of the clutch housing.  It's on both E100 and E5491 but the vertical hole doesn't go through on E5491.  I believe its on diecast engines too.  The only changes I know of at 219 are the size of the front oil gallery plug and one of the bolts at the rear of the case was changed from an 8mm to a 10mm.

[754]

 I just looked at some parts,last night from number 10,XXX.
 Those front upper engine mount bolts, man do the heads ever look different than  the later ones..
 You had mentioned something about bolts the other day, not sure which you meant..

[markb]

I just looked at some parts,last night from number 10,XXX.
 Those front upper engine mount bolts, man do the heads ever look different than  the later ones..
 

Do you mean the big 8's?

  You had mentioned something about bolts the other day, not sure which you meant..

Not sure what I mentioned.

[markb]

I'm still puzzled about the hole in the case at the front part of the clutch area.  Anyone have any ideas?