A Stihl 440 work saw

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Had the opportunity to work over a Stihl MS440 to make it a great work saw. Here's some pics of the journey along the way.

 

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Decided to use a Duke's performance molly coated piston. It was right on the money for height top and bottom.

 

[p61 western]

In before the lock.

 

[661joe]

Why a lock lol

 

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Windows seem a little bit larger.

 

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Skirt is just a touch wider.

 

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I don't have a really good scale for fine measurements, but with the supplied pin it weighs out about the same as the original. With the Stihl pin about .2 ounces less. I used the beafier supplied pin to soak up heat and take more abuse.

 

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Zeroing the run-out to cut the squish band.

 

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Cutting the base on the mandrel.

 

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Final squish clearance at .021".

 

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Time for some voodoo on the degree wheel...

 

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...and applied it to the cylinder.

 

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The Duke's piston had zero resistance in the bore without rings. This also told me that the seals were about done.
Bearings were in great shape.

 

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...in with the new.

 

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The little one too...

 

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... and put em back together again.

 

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New bearing from Stihl took the wobbles out of the drum.

 

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Chose to go with Caber rings just because they are a known item of quality.

 

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A little assembly lube and on goes the cylinder, with a Stihl base gasket for ease of maintenance.

 

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Advanced the timing and gapped the coil with the Stihl tool.