Topic: Who knows CB750 K0 cylinder head vagiaries?

[Terry in Australia]

Well I sold the later K0 head a couple of weeks ago, and I thought that was the end of it, but then I came across this pic of a head from an early sandcast K0 which is different from the other two! I do remember reading somewhere here that there were at least 3, maybe 4 different K0 heads, so I'll add one more to this thread, just in case someone else is interested. Can you spot the difference?

Weird K0 head by terry prendergast, on Flickr

[KayOne]

Okay, I"ll guess, no press in oil jets, From the picture the oil jet holes appear to be drilled in the casting.

[754]

There is a mould or spruce dot, outboard of each valve guide.
 And there is a boss intersecting the rib in the missing bolt area.

[BPellerine]

the sandcast guys say that is a transition head,with the front boss provided for the front hole but never drilled,my 71 head has those dots.bill

[Sgt.Pinback]

Terry, do you have the correct breather cover for that early head?

[PeWe]

EX guides as my K1 head on my k2 build  no guide seals.
My K1 head has press in oil orifices like shower nozzles. Not drilled direct in head as your early one. It has grainier alu than my K6 head which I noticed when repairing threads with time-serts. I torqued the valve cover less than usual.

[Terry in Australia]

Terry, do you have the correct breather cover for that early head?

G'Day Sarge, breather cover, or cam cover? I've discovered recently, with Bill's help, that I don't know sh1t about K0 engines? Tell me what I should be looking for?

[Sgt.Pinback]

Hi Terry,

Depends if you take early cam holders.

See # 272 for different breather covers:

http://cb750sandcastonly.com/smf_forum/index.php/topic,1701.270.html

[Terry in Australia]

Well I found these two in my garage this afternoon, are they the real deal?

K0 breather cover 1 by terry prendergast, on Flickr

K0 breather cover by terry prendergast, on Flickr

[JamesH]

Well I sold the later K0 head a couple of weeks ago, and I thought that was the end of it, but then I came across this pic of a head from an early sandcast K0 which is different from the other two! I do remember reading somewhere here that there were at least 3, maybe 4 different K0 heads, so I'll add one more to this thread, just in case someone else is interested. Can you spot the difference?

Weird K0 head by terry prendergast, on Flickr

Terry - did you win the sandcast cases/frame on eBay then?

[Sgt.Pinback]

Well I found these two in my garage this afternoon, are they the real deal?

K0 breather cover 1 by terry prendergast, on Flickr

K0 breather cover by terry prendergast, on Flickr

Inside Yes but can’t see if they are slightly higher on the rear side (carb side) as shown in my pic in SOOH forum

[Terry in Australia]

Well I sold the later K0 head a couple of weeks ago, and I thought that was the end of it, but then I came across this pic of a head from an early sandcast K0 which is different from the other two! I do remember reading somewhere here that there were at least 3, maybe 4 different K0 heads, so I'll add one more to this thread, just in case someone else is interested. Can you spot the difference?

Ha ha, no mate, I was a very early bidder, but it was way too rich for my budget and anyway, I didn't want to get caught up in the endless pursuit for "unobtainium" sandcast parts. I've got enough parts to build a complete low numbers diecast K0 engine, which I'll then sell to finance my K1 build.

Weird K0 head by terry prendergast, on Flickr

Terry - did you win the sandcast cases/frame on eBay then?

[Terry in Australia]

Well I found these two in my garage this afternoon, are they the real deal?

K0 breather cover 1 by terry prendergast, on Flickr

K0 breather cover by terry prendergast, on Flickr

Inside Yes but can’t see if they are slightly higher on the rear side (carb side) as shown in my pic in SOOH forum

Sorry Sarge, I tried to open it, but didn't see any pics? I think the one on the left is slightly different from the one on the right?

[sandcastcb750]

Seems to me that the sandcast head was used through beginning 1972 or K2. The 750 was severely de-tuned after 1971 so maybe there some other alterations in the head?

[Terry in Australia]

Yeah, I think "severely detuned" is a bit of a stretch, I've ridden every model CB750 and owned many, and apart from hotrodded bikes, in reality they all pretty much felt the same.

The big difference probably had more to do with gearing. Changing the front sprocket from a 17 toother to 18 gave later models a drop in acceleration but a more relaxed cruising at lower RPM's in top gear. The K0 cable carbs had a lighter pull too, which gave the rider the impression that the engine was a lot more willing than later models.

Sure, the K0/K1 might have had a couple more BHP, but nothing that noticeable.

[754]

The 300 pipes helped.
 KO  had 16 45 gearing I think.