caustic soda for cleaning carbon off valves

[el_oso]

should be fine yay or nay?
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Duke 390
Previous: '05 XR125L | '96 XJ600S Diversion |'05 Suzuki GSXR1000 | '05 Honda CBR125-R | '97 YZF 600R Thundercat | '11 Honda CBR250
Car: Jeep Wrangler 4.0L

[ZRX61]

So long as they are in a jar & not still in the cylinder head..

If they are still in the head, use nitromors.

[smegballs]

Thats right, keep the soda well well away from all things alloy. It will happily go on nom nom into your cylinder head with predictable results.

[c_dug]

We're doing the valves at the moment and there is some really solid light colour stuff on the valves that the caustic soda isn't getting off, apparently this is the cylinder that had the leaky valve seal.

Any idea what the stuff is and how to get it off? It's even a struggle to scrape any off with a screwdriver or wire brush it is that hard.

This is the exhaust valve side only by the way, and the lighter coloured stuff is on all of the exhaust valves, just a lot worse on the one that was leaking.

c_dug
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I am a bellend, I am a man of constant sorrow, I am a gummy bear, I am a rock.

[temeluchus]

just be careful not to ruin the stem when your trying to clean it up.
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Some shite cruiser. Now with guns and FREEDOM!

[smegballs]

[temeluchus]

When wire wheel was mentioned, I had visions of someone attacking the valve with a steel brush on a bench grinder
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Some shite cruiser. Now with guns and FREEDOM!

[Cigaro]

Sorry to hijack the thread, but in a similar vein, I have a piston that's totally black in my bike.

Is it worth cleaning up the piston before I put the new valves, head and cam on?

Will that mean taking the piston out of the engine, and what should I use?

[smegballs]

[ZRX61]

[robocog]

Whenever I've done top end stuff the procedure has been

Put piston to close to the top of the bore and smear grease round the edge of the piston to stop bits getting in

scrape any piston crown carbon off with something softer than the piston crown
I've never bothered to polish them, just get them clean enough to check they look ok and any bits that could break free are no longer a threat

When done cleaning turn crank so piston comes down the bore and wipe the carbon encrusted grease out
repeat for other cylinders

I guess the reason I have never bothered to polish the piston crowns is impatienece and knowing that there are usually many valves that also need cleaning and re lapping that time becomes a pressure
If there is no pressure to get things back together and you are doing it somewhere warm or even indoors it could be taken to extremes without having to remove the pistons at little cost other than time

dremel with mini buffing wheel attachment and a steady hand?

Not sure if there are any real world gains that you would notice if you mirror finish the crowns? other than the satisfaction you did a thorough job?