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Discussion Starter #1
Hi,
I'm trying to brighten up the cases on my '81 Darmah. Is it me or did Ducati source the most porous, dirt-sucking aluminum they could find for these things? I've tried most everything I can think of. Simple Green, cream of tartar, Scotch Brite pads, stainless brushes, etc. Still pretty gray. Mainly the cast parts. Polished covers are coming up pretty decent but there's come gray in them as well. I'm not planning on disassembling the engine. Any suggestions appreciated.
Thanks!
 

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There is a guy here locally that has a high pressure water sprayer that really cleans up old metal, including magnesium and aluminum even when zinc anodized. Sorry, I don't know the name of the system he has, but it doesn't use glass or plastic beads - only water and a tiny tiny amount of soap.

If you hesitate to hit the hard chemicals, Purple Power<Aluminum Brightner<aircraft stripper - you might try the high pressure wand at the local car wash to see if it starts to get into the stains you see. Glass beads are a final option but you would have to take the engine out at the very least to use that.
 

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If you don't want to take the engine out then I suggest that you find some one who can soda blast but you will have to take off carbs exhaust etc., and clean up afterwards ( ie pressure spray with water ) while the soda remnants are still wet in the fins. The other option is to locate an operator who can blast dry ice. This doesn't harm engine internals if it gets in and it evaporates leaving the rubbish off the motor. Cheers
Ian
 

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You know, they weren't bright fresh cast looking even when new. Scrub,Scrub,Scrub with simple green usually does it. The trick is not to let it dry out before you rinse it. Soda works pretty well but it does make sort of a mess as it goes everywhere, but water does dissolve it afterwaards.
 

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Bon Vivant
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You know, they weren't bright fresh cast looking even when new.

What makes you say that? I think you are wrong and they were quite bright and shiny with fresh castings when new.

I've had luck with simple green, oven cleaner, aluminum wheel cleaner (just be very careful with it because it will stain and etch other parts) and steel wool/ stainless brushes.

This engine has never been bead blasted, only cleaned by hand, it certainly does not look like a blasted engine but it's, passable:

 

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This is not an easy problem to solve. I have cleaned many a BMW twins main engine casings while still together and in the bike by hosing them time and again with WD-40 over a drain pan and just letting them sit over a period of about 2-3 weeks. This is after I have already cleaned the cases first with carb cleaner and perhaps paint (not lacquer) thinner with a clean chip brush. Every time I would walk by, I would hose them with WD. Every time and just leave it alone. Then I would start brushing the cases with a clean chip brush while still hosing them down with WD. Gradually, the cases give up the dirt and this can be seen in the pan. Oftentimes the ancillary parts such as the front cover or transmission don't come out as well and could never really assess why. Perhaps these are either made of a slightly different alloy or manufacturing process.

I have also used the etching (acid) wheel cleaner, but this will take the plating off installed fasteners and can damage (darken) the aluminum if you leave it on too long. I am talking literally 3-5 seconds on the case and then hosing the case with a neutralizing spray of soap and water. I think the message in all this is to start with the least invasive cleaners possible as you move up the food chain with the more aggressive.

Really, the ultimate weapon here is vapor blasting but in no way can the engine be assembled for this treatment since it contains grit.
 

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Bon Vivant
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This is not an easy problem to solve. I have cleaned many a BMW twins main engine casings while still together and in the bike by hosing them time and again with WD-40 over a drain pan and just letting them sit over a period of about 2-3 weeks. This is after I have already cleaned the cases first with carb cleaner and perhaps paint (not lacquer) thinner with a clean chip brush. Every time I would walk by, I would hose them with WD. Every time and just leave it alone. Then I would start brushing the cases with a clean chip brush while still hosing them down with WD. Gradually, the cases give up the dirt and this can be seen in the pan. Oftentimes the ancillary parts such as the front cover or transmission don't come out as well and could never really assess why. Perhaps these are either made of a slightly different alloy or manufacturing process.

I have also used the etching (acid) wheel cleaner, but this will take the plating off installed fasteners and can damage (darken) the aluminum if you leave it on too long. I am talking literally 3-5 seconds on the case and then hosing the case with a neutralizing spray of soap and water. I think the message in all this is to start with the least invasive cleaners possible as you move up the food chain with the more aggressive.

Really, the ultimate weapon here is vapor blasting but in no way can the engine be assembled for this treatment since it contains grit.

100% !
 

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Automotive spray engine cleaner ? The foaming type so it stays put, followed by scrubbing with a brush, then power wash it off. Carb cleaner will get stains out of porous castings, but be judicious with it. It will damage paint and plastic.
 

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Come in Spinner :)
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Do you have a dry blasting machine?
 
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