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CB466f

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Erwin83:
Thanks for the responses.
I need to correct myself. The supplier (Forseti), didnt say they are the same material, they said they have no specific advice, which I interpreted to “follow honda spec”.

My machinist also had a good look. At first he wasn’t happy that it was “cheap internet stuff”, instead of Mahle or whatever top notch brand he usually gets to work with, but upon inspection, he was happy with what he saw, quality wise. Size wise it’s a different story. His smallest size is 50mm bore. So only 1 mm under the 400 bore size, and sleave lenght he prefers a minimum of 100mm. The 400 sleave is around 90mm. But he could work with it.

At least, they are not forged pistons, which for him means using the normal manufacturer specs.
We also discussed the thin sleaves after boring and I mentioned that too tight of a fit would potentially cause heat issues. He agreed and told me to leave it to him. Which I intend to do. This machinist has litterally decades of experience. It’s one of those old fashioned shops, with no reception. Walk through the door and you stand right between the heavy machinery. I trust him to make it work.

Once done, I’ll ask or measure what the actual clearance has become and report back to you all.

Erwin83:
While I am getting bored, waiting for the cylinders to get bored, (see what I did there... haHAA), a good moment to revamp my cylinder head.

A question about the valves:

First of all, off course I've kept valves very neatly ordered per cylinder.
Next, I've cleaned the valves with the wire brush (brass) and cloth, and the seats as well. Next I cleaned the set (valve and seat) by adding a light rubbing cleaning compound (just household cleaning, this stuff is way too light to actually cut any metal) to the valve and turning the valve in the seat (using a drop of machine oil and a rubber hose on the stem to connect to a drill.
Result is a clean valve seat and uhmm. bum (?). the part that hits the seat at least.

Next, I've checked for leaks by dropping the valves back in the head, and filling the combustion chamber with fuel.
To my surprise, 4/8 are (slowly) leaking fuel. 2 exhaust valves and 2 intake valves.

Is this to be expected? After all, the valves are only closed by gravity, and gravity doesn't affect these teeny tiny valves very much.
Before putting in the time and effort of installing the springs to double check, I'd love to hear from your experiences.

thanks in advance.

(picture is obviously of before the cleaning, there is quite some carbon build-up on the exhaust valves).

taysidedragon:
Use valve grinding paste to get a good seal. I've always done mine by hand by rotating back and forth, never used a drill.

Nurse Julie:
You are doing the leak down test the wrong way round. You need to put the fuel in the inlet and outlet ports, with the springs on, as it is the springs that close the valves, not gravity, and then observe for leaks. And you need proper valve grinding paste to do the lapping in.

Erwin83:
OK, so you would advice cutting/lapping the valve anyways (now that we're here)?
Obviously, I was only cleaning so far. The engine ran well, and there were no signs of leaking or burned valves. (the old 'if it aint broken, don't fix it' idea)

I guess that you're also saying that installing the springs and applying pressure to the seal, the results of the leak-down tests may differ.
I don't see the difference (technically) between adding the fuel in the ports, against in the combustion room. Apart from the the latter is less messy...

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