I know this is backwards but is there a good way to dull aluminum (carb bowls)?

[DW69K0]

I think everyone is over thinking the situation and process. I run an investment casting foundry. When an Aluminum casting is pulled from a mold it is process through a shot blast process to remove any she'll and de-burr the casting. The surface finish is not shiny, but just fresh aluminum. IMHO, the surface finish of an ultrasonic clean carb looks the most like a fresh cast surface, any more prep is over doing the work an original casting would have received.
The carb float bowls are a different story, the early bodies were definitely finished to have a high luster, but not shiny and should look different from the carb bodies. Later production changed and Honda did not invest the time (money) in finishing the bowls.
Mark- I think your bodies are close to the correct surface finish, but an ultrasonic cleaning would improve the appearance of your restoration. The choke arm seems overly shiny to me.
Respectfully,
Duane

[markb]

I found out the carb bodies were cleaned with xylene.  Could that have darkened them?  

My final drive flange (where the rear sprocket mounts) was dull and yellowed in the areas where I couldn't get at it to polish.  I used diluted phosphoric acid on those areas and it cleaned and brightened it really nice.  I had the carbs for 1553 rebuilt at the same time as 97 and they look exactly the same.  I think I will do a little test on those.

BTW, the choke arm is zinc plated as well as the rest of the choke linkage.  Were they originally zinc? 

[4pots1969]

Yes, they are zinc plated... But it is funny because me is the only thing that I found rather successful...
As what, a person has the other notices are different, and it is interesting..

[Sam]

BTW, the choke arm is zinc plated as well as the rest of the choke linkage.  Were they originally zinc? 

Every sandcast I own has blue/clear zinced choke arms and linkage.