Honda CB750 Cylinder Head Refurbishment SOHC | 392 Cylinder Head for my Honda CB750 Cafe Racer | 18
My Honda CB750 Cafe Racer project has suffered a little project creep, what was supposed to be a quick look over of the engine, has turned into a serious rebuild. Having found Yoshimura pistons inside, I have now gone down a route of finding new barrels and having them bored to the correct size. This led to an issue about getting a matching cylinder head. In the last video I explained why I choose to use this 392 head.
What I used:
Valve grinding paste: ebay.us/RQHNA6
Valve lapping tool and paste: ebay.us/urCTve
Valve Stem Oil Seals, CB750 SOHC: ebay.us/1Nk3d2
BLACK E-Tech 400ML Extremely High Temperature Paint : ebay.us/DrPPSA
Although the head looked to be in quite good condition, as usual that was hiding a couple of issues. I found that when I took the valves out that when it had been blasted, probably vapour blasted, that some of the media and damp had been left in the inlet and exhaust ports. So the back of the valves and the seats had some rust on them, and there was still some media present.
I stripped the head down, and soda blasted it with my homemade soda blasting set up. The valve seats and valves weren’t too rusty so they cleaned up OK. I found that most of the valve seats were fine, but one had a little pitting from what I assume was it running a little hot sometime in the past.
I used the normal rubber sucker and grinding paste method to lap in the valves. The one with the pitting did take some time, but I was happy with the result in the end. Although all of the valves had a little pitting on their faces. I have seen this before and it didn’t cause a problem with the engine last time, but it did make getting the rubber sucker to stick being a bit of a challenge on some of them.
I found that the valve stem oil seals were quite hard, so while I had the valves out I replaced them with new ones. I have found on other old engines that if you don’t do this that you get some oil burning at start up where oil has leaked through the seals.
Finally I painted the head with XHT black paint to match the barrels. I then put it in the oven for a couple of hours at 160c to cure the paint. Overall I am quite happy with the head and think it should work well.
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