Topic: Honda CB750 oil delivery to the top end

[Rocky2010]

Honda CB750 oil delivery to the top end

Currently I have my engine apart had it hydroblasted which came up fantastic as it normally does and I have done this to other engines I have rebuilt.
Question is I cannot seem to find a diagram of the top crankcase with the head studs removed to see where the oil gallery is to supply the top end with oil. I do know from the diagram that it does travel along the long oil gallery which goes across the top of the top crankcase then it looks like it goes up along side of the 2 rear inner head stud bolts either side of where the cam chain runs. Im thinking there is a little hole in there somewhere that is at the base of those head bolt studs but I cannot see them. Anyone have a photo of a crankcase on a K2 so I can see where it is.
Tried to blow air and the air seems to flow through one but not the other.
I have cleaned all the galleries on the bottom end also removed the plugs so I can clean it completely.
Any help would be appreciated

[flybox1]

The two rear studs nearest the cam chain tunnel, with the o-ring cutouts.  Small oil holes hiding there.
Best to check for blockage before you get any farther.....double nut and remove those studs for better access.

brandEn's Leak Free Top End thread.  I know its for an F, but still good information.
http://forums.sohc4.net/index.php/topic,107040.0.html

[70CB750]

What he says.^^^

Use a flashlight from the top and look down the oil galley.

[Davez134]

I have a pic of the oiling holes you are talking about here in this thread:
http://forums.sohc4.net/index.php/topic,139768.msg1631224.html#msg1631224
Zoom in on the picture of the upper case and you can see them.

[disco]

Hi Rocky,
I'm in southern Sydney & building an 836 at moment as well. Just had all my engine parts, wheel hubs, brake calipers, master cylinder etc hydra blasted too. I removed those cylinder studs as I bought Ape HD studs for this build. Picture below of the oil passage that connects to the main gallery. The holes are drilled thru at an angle. Be very careful to remove any glass residue. I used water & compressed air & gave it about 3 rounds of each!

[Rocky2010]

Hi Disco
Thanks for the photo which is a great help not only for me but others on the forum.
I knew there were some holes in there somewhere as I could see one hole and not the other but I'm sure one of them is blocked.
The parts will be washed out again before assembly.
Now comes the task of removing all the suds a job I'm not looking forward to then I will replace the old studs with the new APE HD studs

[Rocky2010]

After sometime I have now removed the cylinder head studs most of them came out fairly easy but the last 3 would not budge.
I tried heating them soaking with WD40 the double nut method even a stud removal tool.
Finally I thought I would get out my old Faithfull tool my air ratchet gun, double nut setup again but the nuts were put on so the socket went over both nuts then I squeezed the trigger and then off they came so easy.
So happy as I thought it may have just sheared the studs with the torque that sucker has.
That tool has got me out of trouble so many times. Anyway now its time to install the APE HD Studs 

[disco]

Glad to hear they came out in one piece Rocky.

[Rocky2010]

Thanks Disco
I'm glad they all came out intact, I was dreading having them snap off in the case

[disco]

Hi Rocky,
I know your build is just a little behind mine. Don't make the same mistake I made tonight. Used the rubber band trick to hold the base gasket in position on the underside of the cylinders. After a good 1/2 hr of taking my time & patiently feeding the 836 pistons/rings into the barrels...oh no the base gasket is not exactly symmetrical! It wasn't until I got it all the on that I looked down the cam chain tunnel & noticed the chain & gasket were intimately acquainted.

It's all coming off again! It's a wonder you didn't hear the sobbing from your place

btw 2nd pic is after the gasket was flipped over.

[Rocky2010]

Hi Disco,
Thanks for the info, I guess everything else is full on and its easy to overlook the base gasket.
Sorry to hear that you had issues with the gasket that's a bugger.
What 836 piston kit are you using?
Also where did you get you cylinders bored?

[disco]

Yep, all good now. They're "Cruzin Image" 836cc pistons. They're a tight fit in the barrels at 0.03mm (0.0012 in)  piston/barrel clearance, but thankfully the machinist (Ben) put a reasonably decent lead-in on what remained of the bottom of barrels for me. You just have to be patient & work them in, one ring at a time. Greg Ball Eng did the boring & valve reco for me. They do good work.