Topic: Sandcast Airbox: what are these parts?

[34barab]

There's a schematic of a CB750 Sandcast Airbox on the Yamiya website that shows unidentified parts.  Can anyone tell me what they are in the attached drawing?

[Bankerdanny]

It looks like an oil separator. Does a hose from the valve cover run to the bottom of the box?

[34barab]

Bankerdanny,  oil separator makes sense, but my 69 doesn't have one.  Just looking at their schematics, none of the others hint at it.  Don't know if early 750's had this feature.  Just trying to figure out the purpose.

[Bankerdanny]

It definitely isn't something that my '76 F has, but it does strongly resemble the setup from the 550 where a hose runs from the valve cover vent to the bottom of the air box.

There are several guys out there with Sandcast and early K0 bikes. I am really surprised one hasn't already weighed in.

[kmb69]

I have no idea - never noticed that before on their website.
That schematic must be from a K1 or later since it appears to have ribbed cases.
I have most versions of the CB750 Parts Manuals published in the USA and none of them have that schematic.

[Bankerdanny]

Looking at the CMSNL diagram for the K0 box it doesn't show those parts. I wonder if they were Japan only? I would not worry about it, even if you are doing a concours resto of a Sandcast. Even Yamiya doesn't say what they are and if you look at the painted early K0 cases they sell there is no provision for the breather filters that are in the side illustration.

[kmb69]

Here's the schematic from the CB750 Honda Parts List published 04 1969.
Pretty sure this is the first version ever published.
Considerably different from the one on Yamiya's website.

[34barab]

Yamiya's F-16 schematic is supposed to be for Sandcasts.  But their website also covers the CB400F.  Could it be for that?

[754]

I suspect they were country specific.. like maybe France or Germany.
 on the parts list it clear they did not go to those countries till serial no 5xxxx.
 If you can see the partsbook, it usually indicates when a part went in use , or went out..

[kmb69]

Yamiya's F-16 schematic is supposed to be for Sandcasts.  But their website also covers the CB400F.  Could it be for that?

Yamiya's schematic is for a later model 750. Not sure what model or what country.
Definitely not a CB400F. I could not find a match to Yamiya's schematic on CMSNL.
The schematic I posted previously is genuine Honda for the USA Sandcast.

[754]

Kmb is it an early partsbook ?
IIRC there was a change in the top bracketsm during the KO run .. maybe all sandcast were same, I am not sure..

[kmb69]

Kmb is it an early partsbook ?
IIRC there was a change in the top bracketsm during the KO run .. maybe all sandcast were same, I am not sure..

Yep, 1st one published.
They did change to 3 hole brackets around VIN 4000. And "dimples" were molded in the top of the air box to better clear the frame.

[PeWe]

kmb69 and Frank, you really know a lot about these bikes! 
Gain knowledge after working with the CB750's,  seen the parts, not only reading about it!
This forum is a goldmine of knowledge thanks to you and other guys working with these bikes from the very beginning and writing about it here.

[754]

I had #572 frame no.
 Took me quite a while to figure out they did not have the black boot , where the line comes out of the master cyl.
And later I find out the steel part on upper end of line was shorter.
 I had about 50 pieces on mine that were different from late sandcast.

I have no idea where the bike is now, last saw it at the end of 2000.