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Heavy Oil Saw

Cylinder & Piston Wear

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Here’s a few pics of a piston from a Stihl, first two are intake side, with damage to the lower skirt, the third is exhaust with a couple of dings of some sort on the left. Should I just ditch it, or could I clean it up or run as is?

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Here’s the cylinder that the piston ran in, on the intake side there seems to be a little damage on the same side where the piston is, the plating looks worn.

I have another cylinder, but that looks buggered on the lips of the ports. I’ll post pics later.

Any advice welcome. I’ve honed bores, but these 2 strokes, which I’m new to, are finicky IMO.

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Ist picture is exhaust side, then two of inlet.

 

It looks like something has been ingested from the carb and dinged the piston skirt.

 

A modern stratified intake saw and little wear showing. Have you checked the ring gap?

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The piston looks like it has got too hot for some reason, the cylinder looks OK to me as far as I can see, I don't like the look of the intake side of the piston and would give that a close inspection to ensure it isn't cracked and would think the engine has either ingested a lump of something solid or someone has been chocking up the piston using the inlet port but is less likely as the inlet port looks clean.

My only worry would be the piston skirt is cracked on that inlet side but if that is OK, it should all be fine.

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Ist picture is exhaust side, then two of inlet.
 
It looks like something has been ingested from the carb and dinged the piston skirt.
 
A modern stratified intake saw and little wear showing. Have you checked the ring gap?

I wrote it like I took them, but uploaded them back to front, sorry.
I’m slightly puzzled by it, I have no history of the saw, seller said he got it as a job lot and sold them off. I do think something heavy landed on the muffler, as it’s dented at the top, and the piston mounted AV spring was bent.

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That piston was running in that cylinder you say. ... But my money says that piston wasn't running in that cylinder when it got damaged, how can the piston have got repetitive impact damage and the cylinder get away no damage?

So what's this other cylinder, where did it come from ?

 

Reuse the cylinder with a bit of glaze busting and go for a new piston for peace of mind.

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The piston looks like it has got too hot for some reason, the cylinder looks OK to me as far as I can see, I don't like the look of the intake side of the piston and would give that a close inspection to ensure it isn't cracked and would think the engine has either ingested a lump of something solid or someone has been chocking up the piston using the inlet port but is less likely as the inlet port looks clean.
My only worry would be the piston skirt is cracked on that inlet side but if that is OK, it should all be fine.

I think I’ll get a Meteor piston and new Stihl bearing and clips and run the cylinder. Are the Meteor rings any good? The cylinder looks almost new inside and out, apart from that slight difference in lining colour.

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That piston was running in that cylinder you say. ... But my money says that piston wasn't running in that cylinder when it got damaged, how can the piston have got repetitive impact damage and the cylinder get away no damage?
So what's this other cylinder, where did it come from ?
 
Reuse the cylinder with a bit of glaze busting and go for a new piston for peace of mind.

I really don’t know. Took the cylinder off, ginger carefully, inspected it, thought no too bad, placed the rest under a towel and got on ordering bits here and there.
My eldest (8yo) was helping stuff the bearings back into a case using oven and freezer method and wanted to know how a engine worked, so grabbed a cylinder (the one in pics) and the body.
Obviously going through the motions and noticed the damage, never thought there would be any as the cylinder was clean.

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Bent bits from the saw. It looks like the front handle lower AV mount is bent, it may well meant to be like that.
I don’t run saws for a living, but after using one, thought I’d build one. Be cheaper to buy one, buts what’s the fun in that? The boys kind of enjoy seeing things as well.

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