Author Topic: CB 750 cylinder head - please identify (Read 4698 times)

Sgt.Pinback · « **on:** November 01, 2013, 11:14:49 AM »

As told in my intor, if have got a lot of spare parts with my 1970 CB 750.

E.g. there are some cylinder heads. Some have a stamp ("300") others do not.

To which year do thís one belong to?

Elan · « **Reply #1 on:** November 01, 2013, 11:19:30 AM »

according to hondachopper, 69-71...

http://www.hondachopper.com/engine/engine_timeline/timeline.html

Sgt.Pinback · « **Reply #2 on:** November 01, 2013, 12:07:46 PM »

And those without stamp?

Elan · « **Reply #3 on:** November 01, 2013, 12:27:52 PM »

Quote from: Sgt.Pinback on November 01, 2013, 12:07:46 PM

And those without stamp?

I've been wondering about the stampless myself. I have a stampless one...

markb · « **Reply #4 on:** November 01, 2013, 01:18:56 PM »

Quote from: Elan on November 01, 2013, 12:27:52 PM

I have a stampless one...

Does it have that extra hole in between the 2nd and 3rd exhaust ports? The sandcast heads (and cylinders) don't have that hole. I believe they were changed sometime in the early diecasts.

Sgt.Pinback · « **Reply #5 on:** November 01, 2013, 01:30:08 PM »

Is the "300" stamped head a unique K0- diecast head or the same head on K1-K6?

City Boy · « **Reply #6 on:** November 01, 2013, 01:33:10 PM »

Hi.I am not sure what year head your pic shows but they are not 69 or 70.Those years had no oil restrictors but merely a drillway leading to cam towers.

Jerry Rxman Griffin aka MuthaF'er · « **Reply #7 on:** November 01, 2013, 01:35:52 PM »

It is not a 75/76/77/78 F or a 77/78 K

Sgt.Pinback · « **Reply #8 on:** November 01, 2013, 01:40:34 PM »

another pic of that head

ekpent · « **Reply #9 on:** November 01, 2013, 03:10:25 PM »

A side picture of the head showing the fins and the support bars may be helpful also.

Sgt.Pinback · « **Reply #10 on:** November 01, 2013, 03:46:00 PM »

Voilá

754 · « **Reply #11 on:** November 01, 2013, 03:50:13 PM »

He meant fins on edge of head, but by the top front fin I can clearly see it is 73 or later.

Sgt.Pinback · « **Reply #12 on:** November 01, 2013, 04:03:38 PM »

which edge........

754 · « **Reply #13 on:** November 01, 2013, 04:11:08 PM »

Look at the side of the cylinder hed early has round bard later has oval.
Top front fin edge the early have a curve in the. Right and left sides, the later is 3 straight lines.
Got to run but will post quick pic.

754 · « **Reply #14 on:** November 01, 2013, 04:14:03 PM »

Like this

Garage_guy_chris · « **Reply #15 on:** November 01, 2013, 08:31:54 PM »

Quote from: 754 on November 01, 2013, 04:14:03 PM

Like this

what is considered early and what is considered late? it would appear my 74 has an "early" style head the more i find out the more this bike has some odd modifications...

754 · « **Reply #16 on:** November 01, 2013, 09:43:51 PM »

Early style ran till end of 72 , ans a few early 73 models

HondaMan · « **Reply #17 on:** November 01, 2013, 10:05:58 PM »

It appears to be a late K3 or K4 head.

HughL · « **Reply #18 on:** May 21, 2025, 07:29:58 PM »

Opening it back up, the back of my head has the Honda logo and then a number "6" with no other markings, engine does not have a serial stamped on - Anybody know if the 6 is representative of it being a K6 or not?

scottly · « **Reply #19 on:** May 21, 2025, 07:53:09 PM »

No, the 6 doesn't mean it's a K6 head.

bryanj · « **Reply #20 on:** May 21, 2025, 08:39:22 PM »

Two identifiers i see are
1 small oil restrictors
2 stem seals on all 8 guides

Others will say what years that is

Don R · « **Reply #21 on:** May 22, 2025, 11:50:58 AM »

It takes the early head gasket without the tall seals, has exhaust side valve guide seals, and has the center front bolt, so not diecast, also has late fin supports. I'm going with 73. The cam towers also take the added bolts so they are not early, although many have been changed.
Many of those casting marks were for keeping track of the batch in case there was a defect.

Jerry Rxman Griffin aka MuthaF'er · « **Reply #22 on:** May 22, 2025, 12:40:55 PM »

Not a 392 head however you didn't show the combustion chamber

News:

Author Topic: CB 750 cylinder head - please identify (Read 4698 times)