So I was looking for an 044 project saw...

[stderr]

Mmmmm...humble-pie

So, after being a lazy dog about vacuum/pressure testing, trying my best to ignore everyone I finally went there last night.

If I pull vacuum to 10psi, it will stay...until I rotate the crankshaft back and forth, then it drops bit by bit over a 30 second period, or until I give up pretending, whichever comes first.

When I pressurized to 15psi, it held pressure, almost :bang:. I sprayed a little soapy water on the clutch side, all good; on the flywheel side...it looks like a kid's science fair volcano. :msp_mad:

New seal, at least on the flywheel side...

 

[stderr]

Exhaust Chip Pics

Pulled the jug, cleaned it up some, and it looks to my eye at least like it's a casting flaw. The edge on the exhaust opening looks like a casting, not a rough knocked out piece:

The rest of the jug actually looks pretty good. There are some light scratches on the bore that look like just wear and tear, and a small pit below the exhaust port, and that's about all I could see. Even the combustion chamber looks really clean, very little carbon except for the quadrant bounded by the clutch side and exhaust port:

 

[ZeroJunk]

So, after being a lazy dog about vacuum/pressure testing, trying my best to ignore everyone I finally went there last night.

If I pull vacuum to 10psi, it will stay...until I rotate the crankshaft back and forth, then it drops bit by bit over a 30 second period, or until I give up pretending, whichever comes first.

When I pressurized to 15psi, it held pressure, almost :bang:. I sprayed a little soapy water on the clutch side, all good; on the flywheel side...it looks like a kid's science fair volcano. :msp_mad:

New seal, at least on the flywheel side...

On a saw that has that much apparent use and assuming they have never been changed you can figure that if they aren't leaking they will be shortly. And it's that much more work to go back in the clutch side, so change it out also while you are at it.

 

[blsnelling]

That's really odd. I say run it.

 

[stderr]

Piston Pics...

So, some piston pics:

Clearly somebody's used a piston stop on this before. I think this speaks to rope as a better choice for piston stop.

I also note a small ding along the edge just to the clutch side of the arrow on the piston top. This does not line up at all with the chip on the exhaust port, and there are no marks or scrapes corresponding to the chip.

On the other hand, the skirt is a little tattered on the flywheel side...

Both of the above two pics show a bit of damage on the flywheel side on intake and exhaust. Is this likely due to the leaky flywheel seal?

I don't have an easy way of measuring ring end-gap, but my thought is the saw was easily pulling 150psi before I did anything, so my thought is to just fix the seal and bolt it back together. Opinions???

 

[blsnelling]

Throw a new Meteor piston in it for about $40. That dimple in the crown is from the manufacturing process.

 

[ZeroJunk]

That's really odd. I say run it.

You know, it almost looks like it was in there when it was plated.

 

[homelitejim]

.404 chain is more durable and will last longer, the draw back is cost, 3/8 chain is cheaper. The 066 has plenty of power to pull .404 chain, I have lesser saws pulling .404 just fine, including a 54cc McCulloch, granted it is a gear drive saw. Here is a video of a Homelite 770D pulling new .404 over a 46 inch bar, the 770 is 95cc but 1960 95cc's.
[video=youtube;0o0p8ZDAURM]http://www.youtube.com/watch?v=0o0p8ZDAURM[/video]

 

[stderr]

While I wait for stuff to come in, I now have time to indulge my OCD tendencies:

Brad suggested a new piston, but it really does seem in good shape (compression was 150psi). I measured the diameter at several points on the piston and it's not showing much out of round or worn skirts. The bottom is a little fatter than the top. If I use the diameter at the top of the piston for a reference, measuring in line with the wrist-pin, then measure across intake-exhaust, it's -0.001", but the bottom of the skirt is +0.001".

1. What should the ring end-gap be? I'm measuring around 0.028" for both rings, this seems a little big.

2. Can the 0.5mm base gasket be reused or should I get a new one? The one I have is not torn or creased, but does have a line on it from the crank-case halves.

3. There are three screw bosses around the oil-seal opening behind the flywheel, and I can't fit a socket between them to press in the new seal. Other than shelling out for the right tool, is there a trick, like a chunk of ABS pipe or something?

 

[blsnelling]

That piston looks very worn to me. The piston clearance that matters is between the piston skirt and bore. Ring gap will typically be .010-.015.

 

[stderr]

Thanks Brad. From the bottom of the skirt to the bore below the exhaust port I get 0.005".

 

[blsnelling]

What size feeler guage can you fit in there?

 

[Adirondackstihl]

Throw a new Meteor piston in it for about $40. That dimple in the crown is from the manufacturing process.

Along with new rings and BOTH seals.....not just one.......IMO

 

[stderr]

What size feeler guage can you fit in there?

.003 will fit, 0.004 will not.

 

[blsnelling]

Something doesn't sound right. That would be pretty tight for a new piston. It appears to me that all machine lines are completely worn off the skirts of the piston. You've got to have new rings anyway. Might as well do it right and replace the piston, which will come with new rings. Buy a Meteor piston and it will come with quality Caber rings.

 

[DSS]

Throw all those old parts in the garbage. Get a new piston, 2 seals, an oil line and a base gasket. Why would you screw around trying to save stuff? These guys are trying to help you.

A new 660 is how much in canada? $1400 or more? Buy $100 worth of parts and do it right.

My .02 cents.:smile2:

 

[stderr]

Alright, I have a feeling I'll be eating humble-pie again if I cut this corner, so where does one get a meteor piston for $40 delivered? Keep in mind, I'm in Canada.

 

[stderr]

Throw all those old parts in the garbage. Get a new piston, 2 seals, an oil line and a base gasket. Why would you screw around trying to save stuff? These guys are trying to help you.

A new 660 is how much in canada? $1400 or more? Buy $100 worth of parts and do it right.

My .02 cents.:smile2:

Um, keep going! I think something north of $1300 was before PDI and 12% sales tax, and didn't include a B&C. I think you'd land over $1600 before you were done.

 

[DSS]

Replacement Piston for Stihl 066

This isn't a meteor, some of the guys will tell you if it's as good.

Northwood has very reasonable shipping to canada and they're fast too.

 

[blsnelling]

I've used a couple Episans, no issues. Here's the Meteor piston at Baileys. It's actually $45. LINK