Honda-SOHC
SOHC.co.uk Forums => CB750 => Topic started by: Yurkie on March 01, 2016, 11:27:54 PM
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I am working towards doing a full rebuild and repainting of my engine. Currently the cylinder head is off and I am looking for some direction and advice please.
I assume I need to fully remove the valve stems from the guides, and if so how do I do this? I assume this is required to fully inspect the condition of them?
Then what is my best method to clean, decoke, and then also the preparation of the exterior surface for painting?
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These are the images to go with my post which I was unable to upload last night from my iPhone/
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You need a valve spring compressor .to get them out there's lots of videos on YouTube showing how to do it .if you type in hackaweek cb750 .there's a guy doing step by step videos on restoring one there really good .
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If the top of the valve stem is "Mushroomed" through use you will need to carefully grind off the mushroom to get the valve out and if that is the case I would replace the valves
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@Bryanj ok that makes sense. Can I just push the valve stem out though the guide as it doesn't appear to just want to fall out as I was expecting?
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@yozzer74 yes I've been watching hackaweek, and learning a lot. It's a shame he got the bike already torn down and cleaned up. Although I did watch the aluminium polishing episode today, which I somehow missed before, and he simply uses paint stripper. I am just trying to identify if all the engine was originally black as I appears to have been repainted at some point.
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The stem seal tends to make the valve a push fit rather than a slide out fit BUT removing any mushroom is imperative as if you just hit the valve through you will irrepairably damage the guide which are not cheap, require carefull fitting then reaming and valve seats cutting. All this is imatterial if its an F2 as they eat valve guides for a passtime!!
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Bryan is dead on the money about the F2 valves. I assume its an F2, looks like larger valves plus black engine. You didn't say?
The exhaust valves will probably come out whatever as the guides are usually very worn.
This was caused by Honda fitting larger valves to the F2 to pep up the performance of the SOHC unit until the DOHC engine was ready. In doing so, they had to change the rocker geometry to get them in which resulted on a slight sideways push on the valves that wears them out.
There is a permanent repair solution for the F2 valves available from CycleX in the states. Its not cheap but worth it as you don't need to be pulling the engine every 20K miles.
Good luck with the build.
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Yes it's a F2. I see what you mean about not cheap! I'll put them on the list of parts to order. As Bryan suspect the stem ends are mushroomed, so I'll cut them off this weekend to get them out.
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yurkie, i will be listing on ebay lots of new f2 parts soon, i have new pistons and rings valves valve guides, cylinder heads, all sorts of stuff, a NOS f2 exhaust system,NOS body work,, infact i have a complete bike to sell off, engine frame wheels etc
i will put the parts up on hear first but they wont be give away prices as they cost me lots,,
PETE
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Don't forget Pete, I have first dibs on the exhaust.
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Hi Pete
Will probably be interested in an f2 cylinder head when they come up for sale.
Cheers
Mike