Honda CB750 Sandcast
The Restoration Shop => Chrome - Anodizing and Other Metal Finish Procedures => Topic started by: Steve Swan on November 10, 2015, 12:47:40 pm
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i probably have a couple more thoughts/questions about soda blasting carb bodies, so i thought it probably a good idea to start a thread here rather than reply again in Mark's #97 restoration thread.
i'm mystified by how 1865's carb bodies turned out in the ultrasonic. dark and with some uncharacteristic splotchy reddish staining. fluid in my ultrasonic tank is new, clean, clear. solution temp is same around 125' F. time is same, 35". usually, after u.s. i get, in varying degrees, an iridescent finish.
i DO like the soda blasting idea. and i like how the soda blasted carbs look on you red bike, Ken ! however, if i am going to put on my keen and critical restorer's eye, the clean result appears very white and flat. please know i am not criticizing. just observing.
back in the day, before i had a u.s. unit, i ran carbs through the gallon pail of caustic Gunk carb cleaner. the carb bodies always came out with, in varying degrees, an iridescent finish. SAME for carb bodies going through my u.s. tank. i've not changed u.s. cleaning solution types. everything i have been doing has remained constant.
a few years back, as i recall, we seemed to conclude the iridescent finish on the carb bodies may have been a result of gases drawn from metals during the casting process... or a releasing agent to get the carb body free from it's casting mold... or a combination thereof. i just now that if one takes a wire brush to the carbs, it yields a most undesirable result.
just wondering, if to try to recreate the iridescent finish after soda blasting, if soaking in Gunk bath -and/or- u.s. unit would recover the iridescent sheen... some experimentation may be in order.... i have an affection for that iridescent finish, actually was taken aback with how the 1865 bodies came out, not having produced such a result in the past, using same methods i have always used....
anyway... Hmm. original only once. so far, i do have to say, for carbs that have a really undesirable surface appearance after u.s. or Gunk, soda blasting does a nice job of making a spotless finish....
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I recently did a carb clean and soaked the carb bodies in Pine-Sol cleaner. They came out spotlessly clean and had a slight iridescent finish. I was pleased. I have used other chemicals in an ultrasonic cleaner with varying results from clean and flat to dark discolored. Stay far away from Castrol Super Clean!
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Hi again and thanks for the new thread!
No problem with the keen and critical restorers eye, thats why we discuss this type of matter and thats the most fun in restoring the bikes!
Maybe the paint on my carbs could be taken away with other methods, but I had already blasted the wheel hubs and other things an they looked almost new after that. For me it was a easy choice to test soda on the carbs and it came out quite well.
The pictures are taken with flash so they appear a little more white and flatter than they are IRL. Though I dont think you could see much of a iridescent effect as on new carbs and like aluminium parts often are. Maybe the soda will affect very very very slightly just enough to take away the iridescent effect but even if you look closely you could not see a kind of blasted surface, its more like superclean. I would love to find a method to give back the iridescent effect, but I donīt have those Gunk stuff here in Sweden to test.
I attach another carb picture but it is also taken with a cameraflash. (I know the bowls are the later ones, they are changed now).
/ken
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I've reported this previously. Methylene Chloride is perfect for cleaning aluminium carb bodies. I'd be more than happy to give you some from a 20 litre drum I have in my shed. Alas I'm just a little far away ;D