Topic: How do you get rid of these?!?

[JAG]

I've been poilishing up the engine as best as I can, and first and formost, I would like to thank all of you guys and your expertise.

But I have came across these vein-like impression on the engine, almost like stress marks, and I haven't been able to get them down/off any suggestions on what I can do?

I know the pictures aren't perfect, but my camera is a bit sharty, so I did the best I can. But I'd like to post some pics up that have been finished and polished up, if I may. Just atleast if not anything else to atleast show off my hard work, from yalls ideas and knowledge.

[754]

Its corrosion that has etched in the metal slightly..if you cover a bike with plastic for a winter and it cant breathe you can get a lot of this.

You can sand it with 400 & 600 grit..lots of work ..or get it polished... Flitz polish may get it out..usually  seems to get more corrosion out than some others..

[JAG]

Where can I purchase this Flitz polish?

I have been using the different compounds/rouges for the other components of the engine, starting with Aircraft Remover. After I get passed that stage and start the process with the compounds I usually start with 400 grit then 600, 800, 1000, until I get to the finishing compound to allow a clean mirror finish, but I worked on that section (above the clutch housing) for over an hour to get no where..

That's weird to use plastic for winterizing I can understand why, but I have never heard of anyone doing it. It makes since as to the result of it though. I did find a whole butt load of dirt/caked up mud everywhere though which I found rather confusing.

I guess I'll just have to give it more "elbow" tomorrow!!

[754]

Try an online search for Flitz..I mentioned it before on here but no one else seemed to use it.

I am thinking the heat from a buffing wheel might help.. or just the fact it has enough speed and power.

I am sure a few other suggestions will come along..

[CBJoe]

+1 on Flitz

[TwoTired]

I have and use Flitz and it's very good.  However, I find that Semichrome polish works even better.  It seems to slightly more aggressive than Flitz.  Flitz is a good maintainer of shine. Semichrome is a better restorer to shine.  At. least, that's what my elbow says.  And, some parallel testing on clear soft plastic.

As to the original question.  The aluminum discoloration is corrosion as previously diagnosed.  As aluminum is somewhat porous, It can go deeper than just the surface.  How deep it has gone can only be determined by excavation.  Test one of the marks with some fine grit abrasive (non- iron based) to see just how deep it goes.  Then polish back to the shine you want.

Cheers,

[Tower]

When there's deep corrosion, like you may have on the engine cases, its no good starting with 400 grit.  You can easily use 200 grit and save yourself a lot of frustration.  Remove all corrosion and pits before moving to 400 grit.

[fuzzybutt]

i used scotch brite wheels on a polisher for the corrosion pitted areas. works wonders with very little effort

[HITMAN]

As you described them as vein like lines.  IF they are cold-cast lines (can happen during the casting process with aluminum), you could rub and sand all you want and they may not go away.  I have run across this, fortunately not on a structural or stressed piece.

Hope they are not, and you can rub them out.

[JAG]

I meant to upload some better pictures to show more detail. I'll post them up later tonight.

Like what HITMAN said I believe they could be the cold-cast lines.

They were not very visible until I used the Aircraft Remover on it. I went ahead and concentrated on a certain area even going all the way down to 80 grit sandpaper just to see if it would lift off, and it wouldn't budge.

Thanks for the suggestions guys..

[JAG]

here is a better picture..



<img src="http://img212.imageshack.us/img212/2417/dscn17572xt1.jpg" border="0" alt="Image Hosted by ImageShack.us"/>

[TwoTired]

Ah yes.  Now you know why they were painted at the factory.

Cheers,

[kghost]

Ah yes.  Now you know why they were painted at the factory.

Cheers,

Good one Lloyd.

Quick someone tell him he ruined his sandcast cases..........

[InaneCathode]

You fool!
You ruined your sand cast cases!


Hows that? 

[Tim.]

Just an echo on the note about these sorts of marks being a byproduct of casting aluminum.  I've had some pieces professionally polished and they told me this sort of 'watermark' is fairly common and impossible to polish out.

Your marks look more like physical imperfections on the surface as opposed to discoloration of the material itself.

[JAG]

I'm a little unclear on what it is..  Did 'I' ruin something, or is this just a design flaw of the material itself.

And the only way to get rid of it is to "cover it up" by painting it?

This really, for lack of better terms, sucks.. I have the engine beautifully shined/polished completely, and then amongst it there's this huge eyesore staring you in the face.

[754]

As dies wer from hundreds of thousnd heat/cool cycles they tend to get suface cracking similar to that.

However, I just remembered something....

If it is by chance a former police bike, then I may know why.

On another brand that sells many cop bikes, I have seen the absolute worst imaginable cast parts used on one...fleet prices.. you get them cheaper...

 The thought also occurred to me that since these covers are alloys that perhaps some of the metal corrodes more than other parts, but that would seem like it does not mix properly??

[TwoTired]

I'm a little unclear on what it is..  Did 'I' ruin something, or is this just a design flaw of the material itself.

And the only way to get rid of it is to "cover it up" by painting it?

Die cast metal I made by pouring or injecting molten metal into a mold.  The mold in often heated so the metal doesn't cool too fast as it reaches all parts of the mold cavity.  What you see on your bike is likely the beginning of a production run of parts where the mold likely wasn't at optimum temperature yet.  The molten metal swirled around and when it met other swirls it joined, but was not the same temp, and that makes those ripple/imperfections in finished product.  There can be internal voids (air pockets) this way that will weaken the final product.  (So, they will often scap the first few parts out of the molding/ production cycle)  Your sample was probably an early one that looked decent out of the mold.  Further, some or all of those imperfections may not have even been visible, until you started removing the flash over metal hiding them.  Since the factory painted them, they didn't leak, and weren't in a high stress area, you are probably the first to find those minor "flaws".

None of the metal on a bike is perfect, btw.  You just can't see the imperfections that exist, surface or internal.  You're polishing efforts have just exposed some cosmetic "flaws".  It met original goals.  Just not yours.  So, it is NOT a design flaw.  It is a process anomaly.

In a way, this is favorable to you, as paint will look far better for a longer period of time without frequent maintenance than polished cases will.

cheers,

[JAG]

I'll run a search on some paintings methods, and go from there..

Thanks again TwoTired..

You know your stuff!!!