Stihl 028 super rebuild went bad

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Here's pics of the cylinder. The exhaust side (first pic) has some little scratches that I'm afraid are in the chrome. Thoughts???
 

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yeah that cylinder looks serviceable. Do what you can, toss a piston in there and see about leakdown and compression - might be g2g
 
I hand sanded it and buffed it out with a dremmel, then swabbed it with muratic acid to get any aluminum residue out.
Before putting it back together I would run a home made mandrel with red scotchbrite on it to rough up the cylinder to seat the new rings. After the red SB be sure to CLEAN the jug VERY well with either dish soap and water or something like brake cleaner. You don't want any left over grit to get sucked into the engine or bearings and abrasives WILL leave grit behind.

Mastermind has a video on this site on removing aluminum transfer without acid which shows the process.
https://www.arboristsite.com/community/threads/how-to-remove-aluminum-transfer-without-acid.248325/
You may also find more with a Google search using those key words. Can't post a direct link here. :(
 
Before putting it back together I would run a home made mandrel with red scotchbrite on it to rough up the cylinder to seat the new rings. After the red SB be sure to CLEAN the jug VERY well with either dish soap and water or something like brake cleaner. You don't want any left over grit to get sucked into the engine or bearings and abrasives WILL leave grit behind.

Mastermind has a video on this site on removing aluminum transfer without acid which shows the process.
https://www.arboristsite.com/community/threads/how-to-remove-aluminum-transfer-without-acid.248325/
You may also find more with a Google search using those key words. Can't post a direct link here. :(
Thanks!
 
Can you explain your "swabbing out" procedure?
Here is where things go south FAST. Muriatic acid will quickly attack and dissolve aluminum transfer but NOT the Nikasil plating. However, if you have any gouges that go THROUGH the plating or get it near the edge of the plating on the ports it will eat underneath the plating and ruin the cylinder. That is why it is safer NOT to use acid.
 
Here is where things go south FAST. Muriatic acid will quickly attack and dissolve aluminum transfer but NOT the Nikasil plating. However, if you have any gouges that go THROUGH the plating or get it near the edge of the plating on the ports it will eat underneath the plating and ruin the cylinder. That is why it is safer NOT to use acid.

Exactly why I asked, swabbing out if not followed by a thorough neutralisation will lead to toss away light doorstops.
 
Before putting it back together I would run a home made mandrel with red scotchbrite on it to rough up the cylinder to seat the new rings. After the red SB be sure to CLEAN the jug VERY well with either dish soap and water or something like brake cleaner. You don't want any left over grit to get sucked into the engine or bearings and abrasives WILL leave grit behind.

Mastermind has a video on this site on removing aluminum transfer without acid which shows the process.
https://www.arboristsite.com/community/threads/how-to-remove-aluminum-transfer-without-acid.248325/
You may also find more with a Google search using those key words. Can't post a direct link here. :(

Looks a little rough already?

What grit paper was used?
 
Here is where things go south FAST. Muriatic acid will quickly attack and dissolve aluminum transfer but NOT the Nikasil plating. However, if you have any gouges that go THROUGH the plating or get it near the edge of the plating on the ports it will eat underneath the plating and ruin the cylinder. That is why it is safer NOT to use acid.
Well, i obviously did'nt know that!
Looks a little rough already?

What grit paper was used?
180
 
I used long qtip, dipped it in muratic acid, then rubbed the cylinder walls until it came away clean. Then rinsed it with water.

So not so much swabbed- as dabbed...... dabbed is much better than swabbed.
Bit of baking soda in the water helps neutralise the acid.
 
I use a small 3 stone hone and brake cleaner as lube to do my final pass and set crosshatch, it cuts fast but its only a few strokes. 220grit as i recall, havent had any problems with it snagging ports yet.
f88854f93e4b24e7eed63e52ae979afe.jpg


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Muriatic acid method is pretty risky, by the time you realize you screwed up its well past too late...dine right on a viable jug it gets good results though

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