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how to clean valves properly

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RBoss:
Hi all,

After rebuilding and painting the engine to replace primary chain + rubbers, I am now at the stage of rebuilding and assembling the cilinder head.

I am planning to (lightly, they are in pretty good shape) lap the valves and replace the valve stem seals. I have bought the lapping compound and the suction cup tool and am looking forward to this job. Before starting on that though I want to properly clean the valves from carbon etc.
I have watched several videos on how to clean the valves and on that basis I started cleaning the first exhaust valve by spinning it in a cordless drill using a scotchbrite pad/brass brush to clean the valve (see picture for the result). After cleaning the first valve I had the feeling there was some sort of coating on the valve. My question;

- have I done irreparable damage to the first valve or can I still use it?
- what is the best way to proceed with the other valves?

Pictures:

1. engine in restoration proces ;D
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2. exhaust valves
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3. inlet valves
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Thanks!
Ruben

RBoss:
Extra zoom in on the "scothbrited" valve on which I might have done some damage.
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Bryanj:
To the best of my knowledge standard Honda valves have no "coating" although the tips may be stellite.
The valve seating area on the valve you show does look to be pockmarked and as these faces are not supposed to be machines only lapped you may have a problem getting a decent seal

RBoss:

--- Quote from: Bryanj on January 09, 2022, 06:39:12 PM ---To the best of my knowledge standard Honda valves have no "coating" although the tips may be stellite.
The valve seating area on the valve you show does look to be pockmarked and as these faces are not supposed to be machines only lapped you may have a problem getting a decent seal

--- End quote ---

Thanks for your quick thoughts Bryanj. I am not very worried for a bad seal as there where no problems (to my knowledge) with it before I opened up the engine. I still have to lap the valves with compound so that might also make it better.

Any advice on how to clean the valves/take of the carbon?

Cheers,
Ruben

Bryanj:
Soak in paraffin or similar then the scotchbrite

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