High Quality Chainsaw Bars Husqvarna Toys

Red Armor* Poll

How long? Bare bore, bare piston

  • Not start

    Votes: 1 2.1%
  • Almost tuned

    Votes: 6 12.5%
  • 1st cut

    Votes: 13 27.1%
  • Half tank

    Votes: 17 35.4%
  • Something else failed

    Votes: 11 22.9%

  • Total voters
    48

Red97

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Test
Red Armor 40:1
Bare bore 50mm
Plain uncoated piston
.0025" clearance
Iron ring
14k max rpm with good tune.

How long will it last?

Not even start?

Almost get it tuned?

1st cut?

Half tank?

Till something else breaks first?

Genuinely interested.

Any suggestions on bore finish? 3,4,500 grit?

How much clearance becomes too much?
 
Last edited:

Onan18

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I would venture a guess that it will die a very early death. But, if it makes it past the initial warm up and doesn't cold seize, then probably until something else breaks first.
 

D B Cooper

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by bare bore do you mean not nikasil or chome lined soft aluminum?
 

Red97

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No plating of any kind. Regular jug with the plating bored out and honed to size.

7d1c77574d3d3c5215b943fd4179bd9f.jpg


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Red97

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To me it depends on your static ring diameter. And I think you’ll have a whopped out bore before a seizure.

Just make a 2-piece and have it plated.
You see less static ring pressure beneficial?

I still have to try the iron sleeve first. And no reason for a 2 piece head.

$6 Farmertec pistons FTW

This'll be fun

Link?
 

Stevetheboatguy

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The bare aluminum cylinder will probably wear quickly. The old poulans and briggs that had bare alloy cylinders. Were a different alloy with a high silica I believe. They were quite a bit harder than regular bare aluminum.

But I'm sure you already knew that. You definitely have a extensive knowledge and experience.

But the reason why I bring it up is. You might be able to have that cylinder hard anodized very inexpensively. It will last much longer than bare aluminum and be far less than having US chrome or Millennium technologies plate it. And give you more run time to experiment with porting and such.


Food for thought at least.



Steven
 

Manofstihl661

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This sounds fun but I feel like either I’m not getting what’s going on or some others aren’t.

This is a test to see how the piston and cylinder will hold up under your original parameters correct? Not to get advice on how you could make the piston and cylinder better by playing and such. I’m just asking for my own clarification. Because I like my understanding of it being an awesome test that could work or be FUBAR!
 

RIDE-RED 350r

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Well other than the post above I've never seen or heard of a naked aluminum cylinder. And I would guess that with the cylinders mentioned above, the piston rings would be made out of a very different material that would get along with those cylinders. That iron ring is alot harder than the bare aluminum cylinder material. I don't think it would take long for the ring to wear that cylinder to the point of compression loss, especially with heat introduced. Think of how easily aluminum grinds compared to nikasil plating, steel, or any other material commonly used for cylinder sleeves and plating in cylinders.

I voted half a tank.
 

Red97

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This sounds fun but I feel like either I’m not getting what’s going on or some others aren’t.

This is a test to see how the piston and cylinder will hold up under your original parameters correct? Not to get advice on how you could make the piston and cylinder better by playing and such. I’m just asking for my own clarification. Because I like my understanding of it being an awesome test that could work or be FUBAR!
Pretty much both.

The parameters in the first post are what I am going to use. Only thing I'm not sure of yet is surface finish.

My goal is to test how a cylinder will perform with an over bore before spending the $$ to replate.

Feel free to chime in with thoughts.

The poll was simply to see what others think on the subject.



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Red97

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The bare aluminum cylinder will probably wear quickly. The old poulans and briggs that had bare alloy cylinders. Were a different alloy with a high silica I believe. They were quite a bit harder than regular bare aluminum.

But I'm sure you already knew that. You definitely have a extensive knowledge and experience.

But the reason why I bring it up is. You might be able to have that cylinder hard anodized very inexpensively. It will last much longer than bare aluminum and be far less than having US chrome or Millennium technologies plate it. And give you more run time to experiment with porting and such.


Food for thought at least.



Steven

May be try the anodized in round 2.
 

Stump Shot

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There's gazillions of little four strokes running aluminum bores. No idea the metallurgy involved other than they are pretty much designed to last a couple hundred hours before replacement. You could knurl the piston skirts so as to hold some more oil then hand fit them to the bore, and I second the cheap rings. My guess is it will run for a while OK, the rpm is what is going to kill it sooner as it's just a matter of how many times can the rings scrape up and down before compression is lost. Kinda like how many licks does it take to get to the center of a Tootsie Roll Pop? Interesting test though, look forward to see what happens.
 

Stevetheboatguy

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Well other than the post above I've never seen or heard of a naked aluminum cylinder. And I would guess that with the cylinders mentioned above, the piston rings would be made out of a very different material that would get along with those cylinders. That iron ring is alot harder than the bare aluminum cylinder material. I don't think it would take long for the ring to wear that cylinder to the point of compression loss, especially with heat introduced. Think of how easily aluminum grinds compared to nikasil plating, steel, or any other material commonly used for cylinder sleeves and plating in cylinders.

I voted half a tank.

May be try the anodized in round 2.



Also the engines that ran aluminum bores. Usually had a plated piston to prevent sticking and galling.

I'm very interested to see how long this one will last. Have wondered myself.


Steven
 
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