Secrets of a CB750 early K

[Trigger]

I have many people state that the oil jet is part of the head on a Sandcast, Diecast and K0's. But, I have been removing these for years to be cleaned out properly. They are a well engineered part of the head and come with a strainer on the back and a nipple facing up. If the jet has no nipple, this means that someone had drilled it out before, trying to unblock it.
This can cause many problems as the swarf then sits in the strainer or the drill has gone through the whole part.
Here is a couple of pics:

[Bryanj]

You are never too old to learn something new. Dont supose the later jets will fit the early head?

[AshimotoK0]

Interesting Graham. Never really looked closely at mine. So if they have been butchered what's the solution other than get Rich to make them ?  Those tiny strainer holes look like a challenge, although my mate in Cambridge has the tiniest holes cut in metal that I have ever seen  by laser I think. Any idea of the diameter of the strainer holes?

See you got that new camera I suggested you buy BTW 

[JamesH]

I have many people state that the oil jet is part of the head on a Sandcast, Diecast and K0's. But, I have been removing these for years to be cleaned out properly. They are a well engineered part of the head and come with a strainer on the back and a nipple facing up. If the jet has no nipple, this means that someone had drilled it out before, trying to unblock it.
This can cause many problems as the swarf then sits in the strainer or the drill has gone through the whole part.
Here is a couple of pics:

Is that the head from Chromy graham?

[Trigger]

You are never too old to learn something new. Dont supose the later jets will fit the early head?

No such luck Bryan, I did try to get a few made some years ago but, they are over engineered and no one would even take on the job.

[UK Pete]

Trigg, my sandcast head and one of my 69 k0 heads have a simple drilling which is diaganal and goes straight to the oil feed passage which is the stud next to the cam tunnel, so i am going to have to say not all have them as you say
pete

[JamesH]

And so the plot thickens....

[RGP750]

Pete that's what mine are like

[RGP750]

Here is mine

[AshimotoK0]

Will check mine tonight .. also my mate has his early K1 in bits so will ask him to check that too. Presumably my 10/69 will be like Rich & Pete's. Interesting to see what the sandcast K1 head has.

[UK Pete]

Yes i have checked now and all 3 of my 69 heads are like that, so with yours being the same as mine rich, and also a 69 head i think we can safely say 69 heads were much more primitive and have a simple hole drilled for oil feed, i have also read this somewhere but i am off out now so cant research it for a while
pete

[hairygit]

In some places they are referred to as "oil restricters" so with Honda's policy of continuous improvement maybe the very early heads without them fitted caused problems of some sort?

[AshimotoK0]

Well got home and my camera is behaving like Triggers

But it looks the same as Rich, Pete's etc.  Mine is 10/69 no insert just angled drilling in a round recess. Maybe my mate Chris's early K1 will reveal something. You would have thought they would have fitted some sort of insert though but the bike was rushed into production by Mr. Honda. Put a strong magnet near to my holes and definitely no steel insert fitted.

Or perhaps someone has fitted the top off a pepper pot from a dollies tea set  or watering can

[AshimotoK0]

The plot thickens  Could it be PN 12238-300-300
 The dollies watering can/pepper pot head 


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SANDCAST 4/69 MANUAL NO MENTION OF OIL JETS

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[hairygit]

That could well be the case, as very early motors had NO stem seal on the exhaust valve guides.