Stihl 026 Piston size Question

[Aggie2012]

Working on my first complete tear down and rebuild of an 026.

I've got new bearings, used crank I bought online (my original is locked up at the lower needle bearing cage)
Impulse line, intake boot, seals, and gaskets.
All oem parts

Going to try to clean this cylinder up with with my foredom and Emory.
(Thank you Randy for that thread in AS)

Only thing left to buy is a piston and rings.
I believe I am going to try the Meteor brand but would like to confirm that this cylinder is for sure a 44mm and not the 44.7mm.

I got the below measurements with my caliper and I'm pretty sure I need to go with the 44 but would someone mind confirming here for me?

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[Aggie2012]

Any other advice or things to look out for on this rebuild would be very much appreciated.

Below you will see why I am having to go through this thing.

Also got to use this custom splitter.
(Don't look at the weld bead. I didn't turn my heat down when I burned this 6011 rod so it was ugly to say the least but worked great)

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[jacob j.]

That looks like a pretty standard older 026. I'm not seeing a compression release- if there's no compression release then it's likely 44mm. Since that is the older style piston with thick rings I would guess it would have to be 44mm.

 

[Aggie2012]

That looks like a pretty standard older 026. I'm not seeing a compression release- if there's no compression release then it's likely 44mm. Since that is the older style piston with thick rings I would guess it would have to be 44mm.

Thanks Jake!

You are correct sir. No decomp valve on this one.
I think I'm going to go ahead and get the 44mm piston and be done with it.


Also going to hit the crank case with a heat gun and hopefully the bearing will slid in with little effort.
I would like to put the oil pump on to give me a reference on the clutch side but the pump is plastic. Does anyone see any issues with the pump deforming?



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[drf256]

That's a 44mm.

A few ways to tell visually.

The 44.7 always has a boss for a decomp, but not always one.

The center boss on top of the cylinder thats marked "A" or "B" is machined flat on the 44mm. The 44.7 are cast and rounded.

The 44.7 has writing on the tunnels, the 44 doesnt.

The 44.7 has a step in the base most times. The 44 is solid.

 

[Chainsaw Jim]

Also, your caliper reads 1.726 inches which converts to 43.84 millimeters which would round up to 44mm.

 

[stihl_head1982]

That's a 44mm.

A few ways to tell visually.

The 44.7 always has a boss for a decomp, but not always one.

The center boss on top of the cylinder thats marked "A" or "B" is machined flat on the 44mm. The 44.7 are cast and rounded.

The 44.7 has writing on the tunnels, the 44 doesnt.

The 44.7 has a step in the base most times. The 44 is solid.

THIS!

 

[Aggie2012]

Thank you very much men!


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[Aggie2012]

Another issue

So I got me a foredom to clean up cylinders with but on this particular 026 I don't think it's Aluminum transfer in this cylinder.

Replaced both crank bearings along with seals.......missing lots of "balls" from one side in particular so I don't know if this had anything to do with these deep scratches on the walls.

See below pics and tell me if this is worth trying to salvage. I've already got a new Meteor piston ready to go in. Just don't want to screw it up in this cylinder.

Do y'all think this cylinder will clean up and run or should I find a used one on the bay?

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[PogoInTheWoods]

Minor gouges below the ports and transfers should not be a problem if the adjacent surfaces are smooth with no ridges. Gouges above the ports can typically be cause for reduced compression and possible flaking of the plating from basic ring friction over time. From what I see in the pics I'd just do a red Scotch-Brite routine on that cylinder and run it unless there needs to be some minor x-fer removal or surface smoothing with a more aggressive abrasive first.

 

[PogoInTheWoods]

Hell, I'd almost run that piston too!

 

[Aggie2012]

Hell, I'd almost run that piston too!

Thanks for the advice pogo!
That makes sense if the transfer or gouges are below the ports. But does that effect the primary compression?

Also,
Will this transfer eat up my new caber rings?

I'm all for Savin money so at the very least I'll run her as it is and see where I am.




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[PogoInTheWoods]

Any actual transfer needs to be removed. And if you have a new Meteor piston sitting there, I'm not suggesting by any means that you should use the old one..., just that it doesn't look all that bad -- nothing that some careful and patient smoothing with 20 micron lapping paper couldn't probably handle.

The scratches on the lower part of the cylinder will have no effect on primary compression or performance.

 

[Aggie2012]

That's exactly what I was looking for.
Thank you sir.

I'll let ya know how she comes out.


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