Stihl MS 660 cylinder cleanup

[mikefunaro]

A while ago I bought a low, low hour stihl MS 660 that had been straight gassed.

Leaf cleanup and all that good stuff is just about wrapped up so I'm getting caught up.

The piston is obviously very toasted. I'm wondering if the cylinder can be saved? For the most part I can't catch a finger nail in much of it. There's one bad scratch, but it seems to be more of a ridge so I'm thinking it's just aluminum transfer.

 

[blsnelling]

There is no way to know until you clean it up. There's a very good chance that it can be saved. But, there's no way to know for sure, other than getting in there and doing it. It must be cleaned up spotlessly. Even the smallest amount of transfer must go, or, you'll be back in there again. Have you started cleanup? The last pic of the cylinder looks better than those before, but still has a long ways to go.

 

[mdavlee]

A little heat and acid and it will help get the aluminum off. I did a 357 cylinder a couple days ago that only took maybe 10 minutes with a couple applications of acid and then sand paper.

 

[ernurse]

Muratic acid....take it outside it stinks bad.

 

[mikefunaro]

Do any of you use anything to arrest the action of the acid--something basic like baking soda or is it not necessary after just wiping out the acid?

Also will look for concentration/molarity...you use straight masonry cleanup muriatic acid?

 

[ernurse]

I just use the masonry type.....and then soak in water after acid. I have heard of people coating the ports and other "exposed aluminum" with grease.

 

[xxl]

Acid is cheap you have nothing to lose. I cleaned mine up like that and i was very happy run s great. I am glad i listened to the people on here. Is that a Mahle cylinder?

 

[ernurse]

My newer 660 cylinder is not a mahle. It just says stihl on it and the part number. My newest Stihls are Giardoni.

 

[mikefunaro]

 

[fearofpavement]

Based on the looks of the piston, there may be some cylinder damage. However, I would still clean it up and see whatcha got.

 

[mdavlee]

That KS stamp on the left there is who made the cylinder. Kolbenschmidt

 

[ernurse]

That KS stamp on the left there is who made the cylinder. Kolbenschmidt

At least it's German made. Thanks...never knew that.

 

[ernurse]

I thought the KS was a $. Shows how much of a bunghole I really am.

 

[Valkyrie Rider]

Any progress on trying to clean it up?

 

[bb1100yankees]

My 028 super cylinder looked just like yours and cleaned up nicely and is a runner again...take your time with the acid, after the bubbling stops rinse the cylinder with water. I used some 220 and then 400 wet dry sandpaper to smooth it all out and no issues.

 

[mdavlee]

I reapply the acid 2-5 times depending on how much it keeps bubbling. I've started using sanding wheels to help clean up the transfer that the acid won't remove quickly.

 

[mikefunaro]

It's slow going but progress is being made...so far there are a couple of slight imperfections in the cylinder which I am unable to remove.