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Cleaning titanium valves?

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so i have 2 motors aprart at the moment.

I measured the volume on one of the motors heads (aprilia sxv 5.5) it was a little difficult with the water i used running out one of the exhaust vavles :banghead:

note the camshaft was not installed at this point.

 

i removed the valves seats look good,

valves look good. except the massive build up which weighs probably 1/3 the weight of the valve

 

So, i believe these valves are coated with DLC. they are shiny black on the stems

 

i hear the ti valves come in several flavors

raw titanium - generally not for us motorcycle guys more for uninformed road racers and paved circle track guys

dlc coated - black, good stuff?

Ti ni coated - gold, and good stuff?

Molly coated stems, dull grey?

and also titanium oxide (anodized ti)

 

ive gatered dont, spray chlorinated cleaners on the molly coated stuff,

I have set of ti rods for the dirt stock car they have molly coated thrust surfaces and they are a nice flat grey my valves dont look like this

 

so before i read anything about all this i know do not grind or abraid your ti valves as youll ruin your dlc, or ti ni,

so i used brake cleaner and carburetor dip to no avail

 

read about not using chlorinated cleaner and about pooped my pants!! then though that it was redicilous since im 90% sure they are dlc coated and not molly.

 

i thenn watched a pro circiut video with a guy chucking them in a drill and polishing them up with some red scotch brite and wd40??

can i do this to dlc valves?

 

what do you guys do?

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if your dlc [diamond like coating] comes off via buffing with scotchbrite or simular, id say its not very diamond like eh...

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Wouldn't it be easy to call one of the Race Car guys that sell lots of these DLC coated valves and ask?  Probably the BEST answer?  Let us know what they say!

 

Swiss

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It's a super hard coating much like Nikasil is.  I would assume it would be difficult to damage by abrasion.  Scotchbrite uses aluminum oxide as an abrasive.  Steel wool might be a bit softer and less likely to damage anything.

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I have used red Scotch pads on DLC before and it will alter the thinner parts of the coating, but not really the thicker areas. The valve was spun in a lathe and, admittedly, I didn't care what happened to that particular one.

 

Something mild that may work is media blasting with fine baking soda. I use it in a spot blaster once in a while for cleaning up cylinder heads and it takes combustion carbon right off while leaving the aluminum with a bright finish. Doesn't take any detail out of the metal at all, so maybe it wouldn't hurt DLC.

 

Regarding coatings, AFAIK, anodizing for titanium is strictly cosmetic. TiN(titanium nitride) is ">indeed gold and very hard. DLC, diamond-like carbon, or trade name Casidiam, ">is black and also very hard. It has the benefit of being slicker and a better candidate for use on sliding parts.

 

On the subject of chlorinated solvents, they may or may not do something to the lube coatings, but chlorine ions do cause stress corrosion cracking under heat in the titanium itself. Chlorinated solvents are bad news anyway and fortunately they are not commonly available on consumer product shelves.

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Chlorinated solvents are not bad news, they are awesome but you have to be weary of where you use them (not around heat).  But...They are still commonly available in most states.  California and New York are probably the only two they are not as available.  But it varies from application to application.  Here in California if you buy brake cleaner it will most likely be acetone (which sucks) or hexane (which works ok).  If you buy anything related to electrical like electric motor cleaner it will be either perchlorethylene or tetrachlorethylene.  Both are chlorinated solvents.  Brake clean used to be exclusively chlorinated so read your labels.  It's the only way to know.

Edited by 1987CR250R

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I wonder how well an acid cleaner would work.  Titanium is very inert in acid but I have no idea about the DLC.  If it is "diamond like" I would assume it is not tolerant of acids.

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Chlorinated solvents are not bad news, they are awesome but you have to be weary of where you use them (not around heat).  But...They are still commonly available in most states.  California and New York are probably the only two they are not as available.  But it varies from application to application.  Here in California if you buy brake cleaner it will most likely be acetone (which sucks) or hexane (which works ok).  If you buy anything related to electrical like electric motor cleaner it will be either perchlorethylene or tetrachlorethylene.  Both are chlorinated solvents.  Brake clean used to be exclusively chlorinated so read your labels.  It's the only way to know.

 

I didn't say they don't work, I said they are bad news, which they are. Some decompose under high heat into phosgene gas, some are potent greenhouse gases, some deplete the ozone layer, and most are abundantly toxic. In this case, they compromise titanium as well....another reason IMO to avoid them.

Edited by HeadTrauma

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just pulled apart a TE250 with a lot of miles on it....valves were covered in carbon. Husky valves are notoriously expensive, so put them in an ultrasonic cleaner for a day or so....good as new.

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I have used red Scotch pads on DLC before and it will alter the thinner parts of the coating, but not really the thicker areas. The valve was spun in a lathe and, admittedly, I didn't care what happened to that particular one.

 

Something mild that may work is media blasting with fine baking soda. I use it in a spot blaster once in a while for cleaning up cylinder heads and it takes combustion carbon right off while leaving the aluminum with a bright finish. Doesn't take any detail out of the metal at all, so maybe it wouldn't hurt DLC.

 

Regarding coatings, AFAIK, anodizing for titanium is strictly cosmetic. TiN(titanium nitride) is ">indeed gold and very hard. DLC, diamond-like carbon, or trade name Casidiam, ">is black and also very hard. It has the benefit of being slicker and a better candidate for use on sliding parts.

 

On the subject of chlorinated solvents, they may or may not do something to the lube coatings, but chlorine ions do cause stress corrosion cracking under heat in the titanium itself. Chlorinated solvents are bad news anyway and fortunately they are not commonly available on consumer product shelves.

well i may be just making sheet up but i thought that the valves that wore out rather quickly in the honda crf250 and 450 what was it 02-17?? were ti oxide

you maby be right, I cant recall where i got this information

 

just googled a bit,

says its used and is harder and helps prevent galling, but is verry suseptible to dirt... must be what the older hondas were using

 

while the other colors had figured out something better.

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