Stihl 028 AV Super repair

[acarpenterdad]

Ring gap after cleaning cylinder measured near the top is .008 for both rings.piston taper is 1.8005 at the top, 1.8065 at the bottom.

 

[acarpenterdad]

The cylinder should not have any taper. Cylinders on old equipment w/cast iron liners would wear and have taper or get out of round. Those you could bore out and fit oversize piston.

You can measure crown clearance at the bottom of cylinder with piston upside down. Then compare that with skirt to get taper.

I got an .005 clearance with piston upside down

 

[acarpenterdad]

Could'nt get sqishy without gasket, it dead stopped. With gasket (i didn't put rings in) here what i got; exhaust side .0415, carb side .057, left .0355, right .036., gasket is .022.

 

[LegDeLimber]

Does someone know what the pin to piston top measures?
And how about the pin diameter?
I keep looking at the Stihl piston (with its pop up) and wondering if it would fit into the 46mm cyl of an Echo pb-620 blower....

 

[drf255]

Could'nt get sqishy without gasket, it dead stopped. With gasket (i didn't put rings in) here what i got; exhaust side .0415, carb side .057, left .0355, right .036., gasket is .022.

Makes no sense. If its a headslapper (under 0 squish) then it shouldn’t be over the gasket thickness with the gasket installed.

At least on the 028S I did, it was around .017 squish without gasket. YMMV of course.

What diameter solder are you using to check the squish?

 

[Mad Professor]

Could'nt get sqishy without gasket, it dead stopped. With gasket (i didn't put rings in) here what i got; exhaust side .0415, carb side .057, left .0355, right .036., gasket is .022.

Either measurement or math is wrong. A dead stop means squish is < 0.022" gasket thickness

Does someone know what the pin to piston top measures?
And how about the pin diameter?
I keep looking at the Stihl piston (with its pop up) and wondering if it would fit into the 46mm cyl of an Echo pb-620 blower....

Pin is 10 X 32mm. No idea on crown to pin?

What is stroke on the echo?

 

[acarpenterdad]

Makes no sense. If its a headslapper (under 0 squish) then it shouldn’t be over the gasket thickness with the gasket installed.

At least on the 028S I did, it was around .017 squish without gasket. YMMV of course.

What diameter solder are you using to check the squish?

About .06. So the solder was too thick probably? That carb side squish reading was probably out because I didn't have it close enough to the edge. I do know it turned freely with no solder or gasket.

 

[Mad Professor]

Your previous reply didn't mention there was solder w/o gasket, when it didn't turn. just it was an interference fit.

Use thin, real lead, solder.

Try an electronics store.

 

[acarpenterdad]

Your previous reply didn't mention there was solder w/o gasket, when it didn't turn. just it was an interference fit.

Use thin, real lead, solder.

Try an electronics store.

Copy, my bad

 

[acarpenterdad]

No way around it. Take some Aleve for the arthritis. WD-40 and a couple grits of wet dry sand paper. I go 150, 220, 320 then finish off with red scotch brite. It's going to take several hours. This has been my experience. Supposedly you can use muriatic acid and those long qtips but I haven't tried it.

I did the acid, then 320, then scotch. I think it turned out good

 

[acarpenterdad]

Ok, i've got some solid lead solder .032. I will re-squish 2nite.

 

[HarleyT]

I did the acid

You ought to put that in your signature!!!

 

[acarpenterdad]

You ought to put that in your signature!!!

LOL

 

[PogoInTheWoods]

Check the pin bosses for the "missing" circlips. I've seen em shipped with both installed before. One installed as shipped isn't unusual. Both of em installed is.

Cylinder looks much better after the second effort. Clean it well in hot soapy water and rinse thoroughly. I usually also wipe the walls with a slightly oiled paper towel first to collect any remaining 'crumbs'. Shouldn't see any residue on a clean white towel wipedown when you're all finished.

 

[acarpenterdad]

Check the pin bosses for the "missing" circlips. I've seen em shipped with both installed before. One installed as shipped isn't unusual. Both of em installed is.

Cylinder looks much better after the second effort. Clean it well in hot soapy water and rinse thoroughly. I usually also wipe the walls with a slightly oiled paper towel first to collect any remaining 'crumbs'. Shouldn't see any residue on a clean white towel wipedown when you're all finished.

Copy, thanks!

 

[LegDeLimber]

Pin is 10 X 32mm. No idea on crown to pin?

What is stroke on the echo?

Echo manual/pdf says 35mm stroke with bore of 46mm or 1.81"
Cylinder is closed port quad trans.
I have a new, oem piston kit, packed away somewhere.....
If memory serves me, pin is 10mm, but the length escapes me.
Interestingly, I do remember the piston having no taper or oval/cam shape in its measurements.

Currently In the middle of some AC changes and other household~ish repairs, so everything has been just crammed into any open gap, to make access for work.
I'm thinking a few (low chance) things are gonna get culled as I dig back out of this chaos.

 

[acarpenterdad]

Ok. No rings yet, but i did redo the squish measurements. Exhaust side .0155, carb side .013, left side .0135, right .0155. Thats with no gasket, gently turning flywheel 10 times through tdc.

 

[acarpenterdad]

Here's a list of other stuff i did after my son straight gassed it. Not knowing anything about saws i was shooting in the dark. I took the whole saw apart and cleaned it. Put in new gas and impulse line, new ignition coil, rebuilt the carb., the kill switch was all messed up so i put a normally open single poll micro switch on the body to the right of the carb. And soldered the kill circuit to it. It never ran for more than a few minutes at a time after it was straight gassed. Thats it as far as i can remember. Now to wait for the rings, ugh.

 

[acarpenterdad]

I have the rings! I should have time to get it assembled in the next day or two. Will the .013 squish be enough? Plus the sealant as well.

 

[HarleyT]

Squish that damn saw together and fire it up!!!!