ZA50 Case Polishing: Part 1

So this is my first attempt at polishing a moped engine case, let 

alone polishing aluminum in general. I've ready plenty of posts on 

the Moped Army forum about how to go about achieving a mirror

ball finish on a material so soft and finicky as aluminum. It seems

as though many people take vast and various approaches to polishing

their cases. Below is my account of how and what I was able to

achieve in just 3 hrs.

Polishing my ZA50 case is pretty much the last task that is 

preventing me from completing this build, or at least bolting 

everything together and getting this bike running. I promised myself 

I wouldn't skip any steps or take any short cuts that would prevent 

me from being 100% satisfied with the quality of this build. One of 

these hurdles to overcome is case polishing. Luckily the frigid cold 

air of winter has settled over the city, which is conducive to indoor 

activities, like my task at hand. 

I started with the materials in the above photo. Including Noxon Metal 

Polish, Mother's Aluminum Polish, 600 & 1000 grit wet/dry sandpaper,

and a pile of rags. My attempt at polishing this case is not to smooth

out every imperfection in the case molding, but to buff out the tarnish 

and stains within the top most layer of the aluminum surface. Some 

people start with 200 grit and move their way up to 2000 grit, skipping

only a few grits in between. This allows them to really sand down all 

the scratches and seams. I plan on riding this bike pretty hard here

in the city and I'm sure to put some dings in my case over time, so

for now a light buffing will do best for my intentions with this bike.

I began wet sanding with the 600 grit paper by hand, constantly 

dipping the paper in a tray of water and wiping the sanded areas 

with a dry rag. After reaching a dull but lighter tone of metal surface

I move on to 1000 grit, and again dipping it constantly in water and

wiping with a dry rag. Once the scratches from the previous grit paper

start to smooth out I took some of the Noxon polish and start wet 

sanding with that as the lubricant. The Noxon polish has a very fine 

grit to it that makes it a very fine abrasive above 1000 grit sandpaper.

My last step was to use the Mother's polish and clean dry rags to 

really buff hard into the surface. A very very small amount of Mother's

polish goes a long way. Once your towel turns black, you have to

switch to a clean rag, otherwise you are just rubbing tarnish back in

to your surface.   

After 3 hours of just polishing the transmission cover to my ZA50, this

is where I ended up. The rest of the engine is an indication of what 

the cover looked like before I started.

Though it's not 100% perfect and the surface is still scratched and 

pitted in places, I'm completely satisfied with where I've ended up. 

I plan to leave the cover as is and move on to the rest of the ZA50

engine body. With any luck I may even be able to piece this engine 

back together and mount it onto the frame next week!