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my 86 K75 engine could use a good cleaning. the block looks really dull, with a fair amount of what I think, must be oxidation. i got the grease off it, but would like to get rid of the oxidation, and bring it back to looking orig..
anybody used chemicals and/or techniques that really do the job, while doing no harm to the alum., the seals and gaskets?
many thanks.
 

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Pretty much how you'd clean the rest of the bike, any good solvent is fine for removing grease. I normally just use some carb or brake cleaner for the oil stuff. You can use a hydrochloric acid to remove the corrosion or just buff/polish it with some rubbing compound or buffing compound. You will change the finish though.

http://www.team.net/sol/tech/clean_al.html
 

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Napa aluminum brightener

Go to your local Napa store and get their Napa aluminum brightener.

Spray on... let it foam for a bit... perhaps agitate it with a stiff brush and rinse off.

On some particularly oxidized parts you may need to do it several times and you'll see where it foams the dirt/grunge in more places each time you do it.

Wear gloves and be in a well ventilated space.

Great stuff.
 

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You have a few options. The aluminum brightener suggested above is good. So is muratic acid, which is sold at most home centers. Marinas use it to clean hulls on fiberglass and aluminum boats. I used muratic to clean the motor on a R90/6 boxer I use to ride. It worked great. The trick is to work fast. Spray it on and hose it off immediately. If you wait too long you'll get streaks.

Another option is Simple Green. It's sold at home centers, hardware and grocery stores. Simple Green removes grease and grime. It works best if you spray it on and then scrub areas with a brush.
 

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86bmwk75 said:
my 86 K75 engine could use a good cleaning. the block looks really dull, with a fair amount of what I think, must be oxidation. i got the grease off it, but would like to get rid of the oxidation, and bring it back to looking orig..
anybody used chemicals and/or techniques that really do the job, while doing no harm to the alum., the seals and gaskets?
many thanks.
Fine steel wool. I was using it on another bike that I am restoring and just by chance tried it on my engine parts, does a dandy job and it's not as aggressive as solvents or acids.
 

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I've read that steel wool will break apart leaving little bits of steel that will eventually rust and discolor your aluminum. I have been cleaning my cast aluminum parts with a stainless steel wire brush and either carburetor cleaner or Gunk degreaser for the heavier deep spots. I am happy with the results.

It really shines clean and bright so you have to do the whole thing, you can't just do a spot here and there. Also, I am cleaning my parts off the bike so there is no risk of contacting any painted metal parts like the water pump or oil pan. I'm not sure what Gunk would do to those. It also feels a little like I am removing the patina from an antique so if you don't want it bright and shinny stick with something gentler. In my case, the dirty spots in the cast aluminum were so ugly I am not worried about patina.
 

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Steel wool

kringb said:
I've read that steel wool will break apart leaving little bits of steel that will eventually rust and discolor your aluminum...
You don't smear it on and leave it there, you rub it a bit and blow it off.
Furniture makers have been using steel wool to oil polish wood furniture and apply Tung oil finishes for years and there are even higher quality steel wool pads that contain fewer loose particulates for that purpose. 3M makes abrasive pads that perform the same function without any metal particle transfer, if you are really concerned about it. I found that it did not scratch or alter the aluminum or even the painted engine parts in the least, it just knocked off the stains and corrosion. It's the first thing I ever found that worked on those hard to clean rims.
Try it just a little on somewhere that doesn't show and then feel the difference :hand
 

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86bmwk75 said:
my 86 K75 engine could use a good cleaning. the block looks really dull, with a fair amount of what I think, must be oxidation. i got the grease off it, but would like to get rid of the oxidation, and bring it back to looking orig..
anybody used chemicals and/or techniques that really do the job, while doing no harm to the alum., the seals and gaskets?
many thanks.
From an auto restorer:

Wash the bike very well. Get the oil grease off with elbow grease.

Would advise not to use steel wool. Steel gets caught and rusts, not to mention that it can cause discoloration of it's own and create patterns in the alum.

Get a Mothers Power Ball and/or Mini Ball. And use the Mothers Metal Polish for Alum.

http://www.magandturbo.com/pages/accessory.asp?aid=884296138

Attach to drill and buff away. I have buffed alum with this process to a high gloss.

Now - Get Mother's Back to Black to restore the look of black tubing, plastic parts, etc. It takes out old wax and discoloration and makes parts jet black.

Hope that this helps.

Phil
 

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In aviation we do not use steel wool to clean aluminum, the steel particles are left in the aluminum and start dissimilar metals corrosion.
There is a Simple Green that is made for aviation as the original SG is also corrosive.
Jim
 
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