low hours Stihl 026 needing Piston & Liner

[sloch24]

mine is super clean internaly and is barley broke in and doesnt even pull off 160

I tested mine last week, and it was just over 170. That surprised the hell out of me!

After I saw that, I grabbed my MS260 pro, and it was only in the 160's... I don't know if it's too new, or what, but I assumed the new saw would have higher compression than the old 026!

 

[Brad101]

Just scored a low hours Stihl 026 with scored piston and liner.

it's got less than 30 hours and looks like new.
his kids ran it on straight gas.

it ran but shortly died when I picked it up. compression felt good.
when I got home did a compression check... 190 PSI

yanked off the muffler.. sure enough, deep gouges all over.
removed top end and piston looks worst than liner.

for how bad this looks... really surprised it still did 190 PSI.

who's got the best deal on a good quality Piston & Liner kit for 026?
might as well port and polish while I'm there.

I am kinda surprised after reading through this post and looking at the pictures.

Heres my 2 cents. That piston does not look to me that it was run on straight gas. The exhaust side does not have near enuff scoring, the rings seem to be free and not stuck. Maybe thats why you had such a high compression reading???

Lots of grit in there and micro scores on both the intake and exhaust side.

I would look very close at the bottom end in that saw and all bearings and seals. Also take a good look at the air filter. It is possible the saw got a good dose of water through the airfilter for some time and maybe more than that.

I would not just assume the bottom end is OK by looking at the damage you see then just throwing a new piston and cylinder at it. You may end up with the same problem soon.

 

[Bowtie]

I am kinda surprised after reading through this post and looking at the pictures.

Heres my 2 cents. That piston does not look to me that it was run on straight gas. The exhaust side does not have near enuff scoring, the rings seem to be free and not stuck. Maybe thats why you had such a high compression reading???

Lots of grit in there and micro scores on both the intake and exhaust side.

I would look very close at the bottom end in that saw and all bearings and seals. Also take a good look at the air filter. It is possible the saw got a good dose of water through the airfilter for some time and maybe more than that.

I would not just assume the bottom end is OK by looking at the damage you see then just throwing a new piston and cylinder at it. You may end up with the same problem soon.

REAL good point. I just rebuilt an 026 like that that the piston looked IDENTICAL to that pic. The culprit was the nylon ball bearing retainer on one of the crank bearings. I replaced both bearings because they were nylon retainer bearings. Some "saw builders" dont replace both, but if they are nylon caged bearings and I have to take the saw down that far, I replace both. Just makes sense, and its the right way to do it.

 

[Mad Professor]

Just scored a low hours Stihl 026 with scored piston and liner.

it's got less than 30 hours and looks like new.
his kids ran it on straight gas.

it ran but shortly died when I picked it up. compression felt good.
when I got home did a compression check... 190 PSI

yanked off the muffler.. sure enough, deep gouges all over.
removed top end and piston looks worst than liner.

for how bad this looks... really surprised it still did 190 PSI.

who's got the best deal on a good quality Piston & Liner kit for 026?
might as well port and polish while I'm there.

Boccarradi, OEM STIHL, SP ? NOOOOO doubt!!!!

 

[046]

many thanks for all the feedback!!!

going to try running original piston and liner first...

jug cleaned right up with most ridges from material buildup. instead of being grooved into liner material.

 

[timberwolf]

Jug looks good, but for the cost I would skip on reusing a piston, it may have a fair bit of slop in the bore or messed up ring lands that will come back to haunt you later.

 

[fredmc]

REAL good point. I just rebuilt an 026 like that that the piston looked IDENTICAL to that pic. The culprit was the nylon ball bearing retainer on one of the crank bearings. I replaced both bearings because they were nylon retainer bearings. Some "saw builders" dont replace both, but if they are nylon caged bearings and I have to take the saw down that far, I replace both. Just makes sense, and its the right way to do it.

When replacing bearings you can go to a bearing supply house and get metal caged bearings that match. I stopped buying factory bearings and seals weeks ago. I put all SKF or toyo bearings in saws now.

 

[046]

OK.. thanks ... what's the best place to get a pist only...
P&L set for $85 is pretty cheap compared to dealer prices.

Jug looks good, but for the cost I would skip on reusing a piston, it may have a fair bit of slop in the bore or messed up ring lands that will come back to haunt you later.

 

[046]

thanks for the headsup .. going to local bearing supplier

but Arrrggg... didn't want to split the case too....

When replacing bearings you can go to a bearing supply house and get metal caged bearings that match. I stopped buying factory bearings and seals weeks ago. I put all SKF or toyo bearings in saws now.

 

[blsnelling]

thanks for the headsup .. going to local bearing supplier

but Arrrggg... didn't want to split the case too....

You should be able to inspect the cages as you rotate the crank. You'll get a good look at the clutch side if you pull the seal. I would definately pull and replace both seals. A complete gasket kit with seals will be <$20 from your dealer. PN 1121 007 1050.

 

[Jacob J.]

When replacing bearings you can go to a bearing supply house and get metal caged bearings that match. I stopped buying factory bearings and seals weeks ago. I put all SKF or toyo bearings in saws now.

Just make sure you check the load and RPM ratings on those, there's a lot of replacement bearings in the same size ranges as main bearings on a saw and they have different ratings.

 

[fredmc]

Just make sure you check the load and RPM ratings on those, there's a lot of replacement bearings in the same size ranges as main bearings on a saw and they have different ratings.

Thanks for bringing that up. High load electric motor bearings usually meet the criteria. You can generally pick the type of cage also. General automotive seals work also, just match them up correctly size wise.

 

[blsnelling]

I've gone that route once. I just told them C3 on the tolerance rating. On had seals on both side which I simply removed.

 

[MontanaMan]

I've gone that route once. I just told them C3 on the tolerance rating. On had seals on both side which I simply removed.

Did you have good results with those bearings?

 

[stinkbait]

I've gone that route once. I just told them C3 on the tolerance rating. On had seals on both side which I simply removed.

On my Mono 48 rebuild I got two new bearings that were sealed and only removed the seals that were to the inside of the motor and left the outside ones. The reason I did that was because I could not get seals for the Tacumseh engine, so I had to reuse the old ones. Worked great.

 

[046]

here's the old piston cleaned up... was careful not remove too much material. only tops of groove will touch liner.

will order a new P&L set, then port and polish later.
with only 30 hours on motor .... seals should be good.

will find out soon if bearings got damaged too.
if I've got to split the case, then everything will be done.

 

[timberwolf]

I'd still put it in the bore and test the fit, if there is more than just the slightest play front to back it's not worth re-using.

Ideal piston clearance should be under .005 but if it's up .010 or over it will rattle and rock around wearing out fast. Esp a high reving saw with short piston like the 026.

 

[046]

many thanks for the tolerances.... measured at .009 or too loose.

oh well .. it's back to piston & liner.

I'd still put it in the bore and test the fit, if there is more than just the slightest play front to back it's not worth re-using.

Ideal piston clearance should be under .005 but if it's up .010 or over it will rattle and rock around wearing out fast. Esp a high reving saw with short piston like the 026.

 

[Bowtie]

When replacing bearings you can go to a bearing supply house and get metal caged bearings that match. I stopped buying factory bearings and seals weeks ago. I put all SKF or toyo bearings in saws now.

I get them from the bearing supplier all the time. The problem is the clutch side bearing on Stihl pro saws. Its a proprietary bearing. Anyone else know of a place other than Stihl to get the clutch side bearing?

 

[Bowtie]

many thanks for the tolerances.... measured at .009 or too loose.

oh well .. it's back to piston & liner.

I gave ya Brad C's #. Call him and see if he will sell you just a piston. I bet he will, if he has the 44mm piston(026), and not just the 44.7mm (260).