Topic: which head do I have?

[hapakev]

I recently picked up a 73K motor and was a little baffled.  The head has 5 round bars on the side of the head and looks like other 73 heads. I searched the threads on the forum for head markings and found pictures similar to what I have, but mu exhaust ports have studs.  The 73 heads I found in the searches have spigto style exhaust mounts.  Do I have a different year head?  did the PO put in studs?





Also I could not find any info on these markings, looks like R13 and 63 or 29?





Here is the almost complete engine number

[beelsamin]

The engine number would be a 1973...head could have been changed somewhere in the past?

[MRieck]

That is an earlier head....1973 looks about right.

[cookindaddy]

hapakev:

I'm trying to learn from you here - what is a "spigto" style exhaust mounts? I searched here and am asked if I meant "spigot"? I have the studs on my 78 but I'd like to understand what was used earlier. Thanks.

[hapakev]

The earlier spigot style has an adapter that bolts to the head, then the exhaust header clamps to the adapter.

Mreick:  All of the 73 heads I have seen have the adapter that has screws that thread into the head, but mine has studs for the exhaust like a 77-78 head.  I need to get a header for this engine, but dont know which to look for.

here is an example of what I mean.  This is advertised as a 73 head, but the exhaust spigots screw into the head.
http://cgi.ebay.com/ebaymotors/Honda-CB750-CB-750-73-CB750K-Cylinder-Head-Valves_W0QQcmdZViewItemQQhashZitem5d26ea433fQQitemZ400084845375QQptZMotorcyclesQ5fPartsQ5fAccessories

[hapakev]

is it possible that its a 74 head?  I dont know if it means anything, but this auction says for 74-78 and looks like the exhaust stud application as apposed to the spigot style

http://cgi.ebay.com/ebaymotors/Honda-CB750-F-K-4-1-Ch-BLK-MAC-Exhaust-System-74-78-750_W0QQcmdZViewItemQQhashZitem2558071b5cQQitemZ160390650716QQptZMotorcyclesQ5fPartsQ5fAccessories

Sorry, after reading further, I think this auction is a typo.  Still dont know what I've got.  My header from my 78F motor looks like it bolts up.  I haven't tried it with gaskets, but it seems damn close.

[hapakev]

Im still cornfused.  Does anyone else have a 73K head with studs? 

[MRieck]

Im still cornfused.  Does anyone else have a 73K head with studs? 

Someone could have removed the original spigots to put a Kerker on etc. No big deal at all. The exhaust ports are the same in regard to placement for all years.

[hapakev]

Thanks MReick, in regards to spacing of the collars and header, can I double up exhaust gaskets if I have to?  

[754]

I call that a 72 and down head..

It is starting to look like early 73 may have used them, but late did not. Also not the top fin is different above the exhaust on the front.

Spigot have been swapped with studs, use what you need for your exhaust available..

[hapakev]

Cool, thanks guys.  I appreciate the info, as always