More Stihl 026 woes

[norry]

(Moving my post here from Homeowner Helper)

I'm rebuilding my Stihl 026 after either an air leak or old gasohol mix killed the original piston. Cleaned out the jug, replaced the fuel line, impulse line, and oil seal on both sides, replaced the piston with a Meteor piston. It seemed to pass pressure and vacuum tests, but when I ran it, it ran poorly and ended up scratching the cylinder in pretty short order. Gas was E10 + Stabil + oil. (NEXT gas will be very fresh E0! I finally found a source!)

Took it back apart, ordered a Huztl p/c kit because I was feeling pretty uncertain about my jug at this point, then realized my cylinder actually cleaned up decently. The Huztl stuff came, but the jug was defective and they're sending me a new one. At this point I have a Stihl cylinder that's not too bad, a piston that's questionable (pictures below), a new Huztl piston, the used Caber rings, and the new Huztl rings. My choices are:

1. Rebuild with Stihl cylinder and reuse Meteor piston (but has it already suffered too much damage to use?)
2. Rebuild with Stihl cylinder, Huztl piston, and either the used Cabers (which seem to still be decent) or the new Huztl rings
3. Rebuild with all Huztl stuff +/- the Cabers

Votes? Pictures of Meteor below.

Also: the WT194 rebuild kit I got (K20-WAT) had a variety of parts, some of which are clearly surplus. The impulse side, I understand. But the fuel pump diaphragm - do I use the one made of black material (the same stuff as the impulse diaphragm) or the one made of woven-looking stuff?

Pictures:

 

[redunshee]

That

(Moving my post here from Homeowner Helper)

I'm rebuilding my Stihl 026 after either an air leak or old gasohol mix killed the original piston. Cleaned out the jug, replaced the fuel line, impulse line, and oil seal on both sides, replaced the piston with a Meteor piston. It seemed to pass pressure and vacuum tests, but when I ran it, it ran poorly and ended up scratching the cylinder in pretty short order. Gas was E10 + Stabil + oil. (NEXT gas will be very fresh E0! I finally found a source!)

Took it back apart, ordered a Huztl p/c kit because I was feeling pretty uncertain about my jug at this point, then realized my cylinder actually cleaned up decently. The Huztl stuff came, but the jug was defective and they're sending me a new one. At this point I have a Stihl cylinder that's not too bad, a piston that's questionable (pictures below), a new Huztl piston, the used Caber rings, and the new Huztl rings. My choices are:

1. Rebuild with Stihl cylinder and reuse Meteor piston (but has it already suffered too much damage to use?)
2. Rebuild with Stihl cylinder, Huztl piston, and either the used Cabers (which seem to still be decent) or the new Huztl rings
3. Rebuild with all Huztl stuff +/- the Cabers

Votes? Pictures of Meteor below.

Also: the WT194 rebuild kit I got (K20-WAT) had a variety of parts, some of which are clearly surplus. The impulse side, I understand. But the fuel pump diaphragm - do I use the one made of black material (the same stuff as the impulse diaphragm) or the one made of woven-looking stuff?

Pictures:

View attachment 419254 View attachment 419255

piston doesn't look that bad. That's the Meteor, correct? I'd use it. Insofar as the pump side diaphragm, are they both identical? I normally use the tan one. Wondering how the piston got scratched? You didn't run the carb too lean did you? Did you apply a little two stroke oil to the P&C before assembly?

 

[bikemike]

I love the 026 i have a project 026 pro i did have it running good for the mn gtg tached out 16.300 and dodgegeeks saw 17.800 so for a mild port job and stock carb and intake it ran good all day tank after tank no overheating issues

 

[bikemike]

Yeah i have been looking at checking out the meteor jug kits. The Italian castings are usually very good quality and for the price id be happy to run one after some internal work

 

[bikemike]

From the looks of ur pics id say you got some debris from scraping gaskets and dirt from assembly as ur saw is a bit filthy . When it back together start out with a least a 40 to mix or richer synblend oil for about half gallon to polish parts and seat rings

 

[bikemike]

From the looks of ur pics id say you got some debris from scraping gaskets and dirt from assembly as ur saw is a bit filthy . When it back together start out with a least a 40 to mix or richer synblend oil for about half gallon to polish parts and seat rings

 

[fearofpavement]

From the looks of ur pics id say you got some debris from scraping gaskets and dirt from assembly as ur saw is a bit filthy . When it back together start out with a least a 40 to mix or richer synblend oil for about half gallon to polish parts and seat rings

That saw is filthy? Guess you never worked on a saw that was a tree service castaside then eh? I've seen saws with so much crud on them you could hardly tell what brand it was.

 

[Knobby57]

I would clean up that piston and use it well before a hultz . Can you post a photo of the jug ? Are you sure you got it clean . Sort of cleaned up does not cut it . You have to get out 100% of the transfer


Sent from my phone when I should be working

 

[bikemike]

That saw is filthy? Guess you never worked on a saw that was a tree service castaside then eh? I've seen saws with so much crud on them you could hardly tell what brand it was.

oh yeah my 026 was plugged almost no av cause of crud build up. But saws i use and own and arborist saw get blown out or power sprayed often so i dont over heat them. The lil grey echo and orange echo are daily runners. But they dont look like they are cause i take care of my ****

 

[pioneerguy600]

I just completed full rebuilds on 7 of these 026`s, I do them each winter as a hobby/pastime in the off work hours.
Your piston looks to be reusable but I am interested into why it scratched the cylinder. Did you measure the ring end gap prior to installing the piston and rings into your original OEM cylinder?

 

[pioneerguy600]

oh yeah my 026 was plugged almost no av cause of crud build up. But saws i use and own and arborist saw get blown out or power sprayed often so i dont over heat them. The lil grey echo and orange echo are daily runners. But they dont look like they are cause i take care of my ****

Hey Mike,..I am with you on keeping the saws clean, I hate running dirty saws and all OPE as its detrimental to them in so many ways. I see them come in all the time so caked up with gunk that at times the cylinder fins are not even visible....yuck!!

 

[bikemike]

Did you see the specs of dirt in the ring channels. And the rub mark on the intake skirt. Thats why i think its dirt that got in during the build and from intake boot

I just completed full rebuilds on 7 of these 026`s, I do them each winter as a hobby/pastime in the off work hours.
Your piston looks to be reusable but I am interested into why it scratched the cylinder. Did you measure the ring end gap prior to installing the piston and rings into your original OEM cylinder?

 

[pioneerguy600]

Did you see the specs of dirt in the ring channels. And the rub mark on the intake skirt. Thats why i think its dirt that got in during the build and from intake boot

Yes I did but it might have gotten there on the teardown. When I take any saw apart it will be as clean as can possibly get and I keep cleaning as I remove each part. Not a speck of dirt will be found loose on any saw I do, any engine for that matter. Not all mechanics/people believe in working on clean stuff but I do.

 

[bikemike]

Oven cleaners for burnt on crap brake clean to rinse everything and a good scrub on all easy to get too parts my new used 6 dollhair echo 510 was a mess but it cleaned up nice and not done cleaning yet before i split the clam

 

[norry]

Wow! Thanks for the responses! To answer the various questions that have been raised:

- Yes, the piston in the picture is the Meteor. I didn't install the Hutzl one. I did oil the piston and cylinder with 2 stroke oil before assembling them.

- The two pump diaphragms looked like they were exactly the same shape, just different material. The Walbro diagram just shows the shape and doesn't seem to specify a material anywhere.

- It's possible that I ran it lean, because I didn't fully rebuild the carb the first time I rebuilt the saw. My local saw shop sold me some kind of very limited rebuild kit that basically just had gaskets and diaphragms, so I didn't fully clean out the carb. This time, I went on Ebay, bought the correct kit for half as much money, and fully rebuilt it.

- It's also possible that an air leak was the problem, because when I took the jug back off, I noticed that it was awfully easy to unscrew the clamp holding the rubber tube (to the carb) from the jug. I thought I had tightened that enough, but maybe not.

- I think Pioneerguy600 is right that the dirt is from the teardown. It wasn't immaculate before, but believe it or not, it managed to get pretty dirty just test-running it. I was on probably 25:1 mix, so things got pretty sooty in the cylinder too.

- I didn't measure the ring end gap. How do I do that? What should it be?

Should I do anything to the piston before reinstalling it? Clean it up at all? If I should, what should I do?

 

[pioneerguy600]

To measure ring end gap you insert the piston ring into the cylinder, making sure the ring ends are clear of any ports and will stay supported on the cylinder wall, take the piston and push the ring up just above the exhaust port, at that point take the piston out and then measure the gap between the ring ends with a blade type feeler gauge. A gap of .008 - .009 is good, any tighter than that could cause the ring ends to contact each other when heated up.
, if they contact together they can scratch the cylinder or even pop out into a port and cause ring breakage.
The piston is fine as is, don`t rub it with anything like sandpaper as that will just take off metal unnecessarily, use Scotchbrite to give it a once over and it will be fine, clean it up real good, hot soapy water then rinse under hot water . Dry it and lube it before assembly.

 

[norry]

To measure ring end gap you insert the piston ring into the cylinder, making sure the ring ends are clear of any ports and will stay supported on the cylinder wall, take the piston and push the ring up just above the exhaust port, at that point take the piston out and then measure the gap between the ring ends with a blade type feeler gauge. A gap of .008 - .009 is good, any tighter than that could cause the ring ends to contact each other when heated up.

Thanks for the explanation! That was easy to follow. I'll do that when I get home.

The piston is fine as is, don`t rub it with anything like sandpaper as that will just take off metal unnecessarily, use Scotchbrite to give it a once over and it will be fine, clean it up real good, hot soapy water then rinse under hot water . Dry it and lube it before assembly.

10-4 good buddy! Will report back on how it goes.

 

[blsnelling]

There's no need to run your mix that heavy, not even for break-in. Your not doing the saw a favor.

 

[Mad Professor]

There's no need to run your mix that heavy, not even for break-in. Your not doing the saw a favor.

here it

NOT to upsurp Brad....

But a little lube, where it needs it,......

 

[norry]

Update: checked the ring gap using Pioneerguy600's instructions. It appears to be right around .008, maybe a little less. The .006 feeler passes easily, the .008 one passes with modest resistance.

Got the piston off, now to clean it up with the scotchbrite and reinstall it.

My replacement cylinder from Hutzl (after the 1st one was defective) came today, and I gotta admit it's about 1000% better than the first one they sent me. Unlike the first, it wasn't shrink wrapped but was just set inside a Farmertec bag and box. Got a feeling they hand selected it because in addition to the casting being good, it had no bits of loose metal from the machining process (first one had these little curls of aluminum in various places), and way better chamfering on the ports. If the Mahle cylinder doesn't work out well, I'm curious to see what this one would do.