Thanks for the update Mike, we now know what is wrong and just need to fix it, but documenting the fault is very important, so we do need those pictures.

If you look at the line of icons at the top of the posting box, you should see this:
[Linked Image]

The icon you need is circled in red. If you click on it you will get this:
[Linked Image]

Click on Browse. Navigate on your computer to the first picture and click on it. Its location should appear to the left of the Browse button. Click on Add file from your PC. It should then be uploaded and a thumbnail of it will appear on the screen. Repeat the Browse and Add File steps for each additional picture, up to a maximum of ten. Then click on All Done.

The valve guide was originally driven in from above, and can be driven back in to its original position by using a generally similar technique. Honda's valve guide driver tool is special tool no. 2 in this set:
[Linked Image]

The smaller diameter of the tool is a good sliding fit to the inside of the valve guide, and the outside is a good sliding fit into the cylinder head where the guide drives in. A series of light hammer blows on the end of the tool forces the guide into place.

However we have a couple of hurdles to jump at this point. First, Honda does not authorise the replacement of valve guides in the GCV engines (though it does in the GXV engines):
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The second hurdle is that you cannot use an ordinary valve guide driver to push the guide back in, because there is a valve stem inside it.

The way I would proceed in this matter, is to make a tool to suit your needs. Here are the valve dimensions:
[Linked Image]

You need to find a piece of steel bar of between 10 and 20 mm diameter, about 50 mm long, with flat ends that are square to the axis. Then you need to drill a 5.5 mm hole through it axially. It should drop over the valve stem, and rest against the top of the guide. This will be your valve guide driver tool.

The next step is to clean the outside of the guide to remove all traces of oil, using something non-residual such as iso-propyl alcohol. Paint the outside of the guide with Loctite or some equivalent product that has an extremely thin coating thickness, and will keep the guide from coming out again. Do not get this stuff on the valve stem of course - that could end badly.

You can then place the tool over the valve stem so it rests against the top of the guide, and tap on the top of the tool with a hammer, which should drive the guide downward. Watch that you don't begin to hit the top of the valve stem: if the stem nearly reaches the top of the tool, remove the tool and rotate the engine slightly to lower the valve into the cylinder. Continue driving the guide into the head until it protrudes the same distance as the inlet guide. It is to be hoped that the Loctite will imobilise the guide so it doesn't come out again. Then you can reassemble the valve spring and retainer, install the rocker arm, remove the rope through the spark plug hole, and repeat the process of rotating the engine while checking that the rocker and valve have additional movement available, even at maximum valve opening on the camshaft.