Piston plating

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charlesv842

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Quick question: when you have a low-end model, often the piston will be chrome plated. Do they only plate the skirt, or do they just let the entire thing get plated?
 
Here's one from the Poulan I just ported (slightly modified):

IMG_2334-1024.jpg

The top and skirt are plated.

They work fine, but the cylinders are intolerant of any foreign material - carbon, etc. I like the chrome bore/bare piston versions better.
 
I've only seen chromed pistons on Poulans. Other brands may have done it as well. On some model variations the piston was aluminum with a chromed bore and others had a plain aluminum bore with a chromed piston. I think the 3.7 Craftsman/Poulan had these variations.
 
Interesting. But you still haven't answered my question: Regarding the piston only-is the entire thing plated or just the skirt? If so, how do they do that? Chris, you said yours is plated on top?
 
I know that the Poulan 42cc clam shells comes with two possible setups. Both using NCC setups. (NCC = Nickel Ceramic Coating) The nickel burns off leaving only the ceramic behind.

1> NCC cylinder and plain piston. Very finish on the initial cylinder finish.
2>NCC piston and plain cylinder. And yes they coat the entire piston but the finish is very smooth and I can't tell from a plain cylinder; just a small size difference.

Note: The NCC piston with not fit the NCC cylinder and the plain piston is too loose in the plain cylinder. I learn this from converting a Poulan 4218 over from the NCC piston to the NCC cylinder. That plain cylinder was easily destroyed on the saw I was saving.
 
I know that the Poulan 42cc clam shells comes with two possible setups. Both using NCC setups. (NCC = Nickel Ceramic Coating) The nickel burns off leaving only the ceramic behind.

1> NCC cylinder and plain piston. Very finish on the initial cylinder finish.
2>NCC piston and plain cylinder. And yes they coat the entire piston but the finish is very smooth and I can't tell from a plain cylinder; just a small size difference.

Note: The NCC piston with not fit the NCC cylinder and the plain piston is too loose in the plain cylinder. I learn this from converting a Poulan 4218 over from the NCC piston to the NCC cylinder. That plain cylinder was easily destroyed on the saw I was saving.
They may have changed coating/finish types on the later 42cc clamshell engines - earlier ones (non-strato) used chromed pistons/bare cylinders, while Poulan Pro versions used chromed cylinders/bare pistons. I believe they made both variations of other saw models too, including the 46cc clamshells as well as older models.

And yes, if you try to use a plated piton in a plated bore it will seize (don't ask...).
 
Great, I think that answers it. Follow up question!! How do they only plate the cylinder sleeves then?? Do they mask the outside? I can't find any demos on youtube.
 
I have received a few of the real cheap Poulans that have toasted cyl/pistons. The 2051 type1-5 , 2050, and 2175 all have the same part numbers for piston and cylinder and they all have cylinders with no plating and pistons all plated with VERY THIN plating.
 
Poulan 3000 Countervibes were made that way. I'm not sure about the 3400. The 4000 had a chrome/NiSi bore with bare piston, the way all pro saws are made.

The 3000 and its brother the PP 305 were chrome bore with thin ring pistons, top notch runners.

The 3400 was plated piston as well as the 3800. There were others too, some of the Micros, 3300, and some Craftsman versions.

The high silicon coated aluminum bores work very well and are a lot tougher then most folks would imagine. I have seen 3400's run without air filters and the rings wore slap off of them but the bore was still good. New set of rings and back in business.

The chrome plated piston, aluminum bore stuff has been done for years and years, Briggs and Stratton was famous for doing that as well.
 
Quick question: when you have a low-end model, often the piston will be chrome plated. Do they only plate the skirt, or do they just let the entire thing get plated?

The only two I've seen were wholly chrome plated but, admitedly, I've seen just two because usually it makes zero sense opening such cheap engines.
 

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