New project saw: 026 Pro - couple of questions.

[kiwiguy]

Long time no post, but I'd been keeping an eye out for an 026 or 260 since my MS260 got stolen a couple of years ago (grrr!). The second hand supply has really tightened up on these over the last while.

Anyway, I finally found a reasonable condition 026 Pro (decomp. valve + adjustable oiler). Tidy plastics, no missing screws, just a worn out decal plate and missing decomp valve rubber shroud. The saw starts and idles easily, and cuts OK - but I think it has low compression (not formally tested, but I can't pick the saw up by the starter cord - the compression won't hold the saw's weight, and she lacked power in a 16" stump cut). Piston & jug look fine - no scoring - but one of the locating rings in the piston groove was broken, so the ring wasn't in the correct place). There was moderate carbon build up on the top of the piston.

I already ordered a Meteor 44.7mm jug + piston kit, with a view to a top end refresh. Was going to do a gasket delete - but the meteor jug & domed piston only has a clearance of 0.011", so that's a no-go. Another option I 'spose is to pick up a 44mm piston only, and try it in the OEM jug.

Couple of questions:

1. Anyone know where I can get a new name plate (part #1121 967 1512)? There's a seller on ebay (https://www.ebay.com/itm/361902089187), but they don't ship to NZ.

2. I presume I'll need a 0.5mm base gasket, since my gasket-deleted squish is only 0.011" ?

 

[ballisticdoughnut]

I believe there’s only one cylinder gasket available for the 026, not sure on the thickness but it’s likely 1mm. If it were my saw I’d get a OEM piston and base gasket. Stay away from the aftermarket stuff. I’ve got a low hour 026 pro, all I’ve done is a muffler mod and plugged the decomp. Haven’t felt the need to go further with it.

 

[kiwiguy]

According to this there are two thicknesses:
https://www.diyspareparts.com/parts/stihl/diagrams/026-pro/bc12137f-2a72-41f7-8c3d/
My local Stihl shop will probably just have the 1mm. I might get a quote on just a 44mm OEM piston kit as well.

 

[trains]

There are 2 base gaskets, the 1mm one for low comp, low quality, low octane fuel, and 0.5mm for higher comp, higher octane fuel.

If your using 91, then run the .5 gasket, pt #, 1118 029 2306

if the cyld is ok, then just replace the piston and gudgeon bearing, give the cyld a quick cross hatch with some scotcbrite to take the shine off it, and no more.
44mm piston pt # is 1121 030 2001

get a gudgeon bearing whilst your at it, the piston comes with 2 clips, and the gudgeon pin, but no bearing.
Pt # 9512 003 2250

 

[kiwiguy]

Ouch. The OEM piston is $230NZD, which is too rich for my blood for this saw.

I'll just run with the 44.7mm meteor piston and jug for now. It came with caber rings, and looks well-machined, and should have a high compression with the 0.5mm gasket.

 

[thompsoncustom]

I presume I'll need a 0.5mm base gasket, since my gasket-deleted squish is only 0.011

Just make your own gasket out of some computer paper and moto seal, i think mine measured .004 which would put you at .015 squish which is what I consider perfect for a 50cc saw.

 

[muddy42]

I've used a few meteor piston kits and always found them excellent. Just clean and polish up the cylinder and replace the piston using plenty of lube. I just use a standard width gaskets as I am not keen on mods (the saw will be much improved anyway) and I feel they give more protection against future air leaks. Ideally pressure and vac the saw after assembly.

 

[kiwiguy]

Nice.

Saw is back together with the 0.5mm gasket and 44.7mm meteor piston. Ended out with 0.022" squish. The compression now feels 'normal' in terms of resistance on the starter cord.

Did a muffler mod (added an additional 2 x 10mm drill holes behind the spark screen), ran a tank of 40:1 through the saw, got a 2nd tank of 40:1 in there, then tuned to 13,500 rpm, sharpened the chain and .... ahhh - lovely. Now *THIS* is what I remember my MS260 cutting like!

 

[kiwiguy]

So - I'm glad I didn't have leaky crank case seals BUT I didn't see the meteor piston circlip instructions to ensure the opening is either facing up or down. Should I be bothered pulling the cylinder and checking the orientation?

 

[2StrokeFondler]

So - I'm glad I didn't have leaky crank case seals BUT I didn't see the meteor piston circlip instructions to ensure the opening is either facing up or down. Should I be bothered pulling the cylinder and checking the orientation?

I've seen OEM installed pistons where the orientation was "wrong", but for peace of mind, I install mine the "right" way. I would pull and check it, but maybe that's my German upbringing

 

[SteveSr]

So - I'm glad I didn't have leaky crank case seals BUT I didn't see the meteor piston circlip instructions to ensure the opening is either facing up or down. Should I be bothered pulling the cylinder and checking the orientation?

Yes! This will keep the end of the clip from compressing on direction reversal and possibly jumping out of the groove

 

[thompsoncustom]

Does the piston direction on a non-ported 026 matter....No it doesn't.

Are your circlips being in the wrong orientation going to cause any problems......Probably not, but if I was going to go through the work of opening it back up I'd put in the Stihl style circlips or cut off the ears.

 

[SteveSr]

Does the piston direction on a non-ported 026 matter....No it doesn't.

I think that it does... The correct orientation keeps the ring locating pins out of the exhaust port.

 

[Mad Professor]

Does the piston direction on a non-ported 026 matter....No it doesn't.

You'll hang the rings in the ex port

Are your circlips being in the wrong orientation going to cause any problems......Probably not, but if I was going to go through the work of opening it back up I'd put in the Stihl style circlips or cut off the ears.

More so with the eared ones.

 

[thompsoncustom]

I think that it does... The correct orientation keeps the ring locating pins out of the exhaust port.

You'll hang the rings in the ex port


More so with the eared ones.

From both of your comments I take it neither of you have had a 026 apart? I am currently running one with the piston turned around it's not a problem on this model.

 

[kiwiguy]

The meteor piston kit I got has circlips without tags / ears. They're simple open ended rings. I'll pull her back apart on the weekend & align the grooves as per recommendations, thanks all!

 

[Mad Professor]

From both of your comments I take it neither of you have had a 026 apart? I am currently running one with the piston turned around it's not a problem on this model.

I own 3 of them (026), I've had them apart, along with a dozen more of my Stihls

Why do you think Stihl Meteor Mahle.......etc All put arrows on their piston crowns pointing towards the front/exhaust?

Would you believe the 026 Shop Manual?

Tell us when you snag a ring.......

 

[thompsoncustom]

Well not all pistons have arrows on them and not all cylinders care which way the piston goes. The piston arrow is nothing more than a easy way to make sure people don't screw something up on the ones that do matter.

People build saws all the time with the pistons flipped around sometimes on purpose when porting sometimes cause they don't know what there doing. What matters is the location of the locator pins and on this model the pins are just outside of the piston skirt so you are no more likely to catch the ring pointing it either direction on a stock 026.

Now below are pictures of the pins on the piston and the cylinder port locations so you can see that it doesn't make any difference which way to flip it on a non-port one. I also added dots in the cylinder to where they approximately are as the intake port width is alot smaller then the skirt width.

 

[stihltech]

Not all pistons have arrows on them???
I would not be using those pistons. Pistons are not round. The rings are also oriented so as not to hang in ports.
But hey, what do manufacturers know.

 

[thompsoncustom]

yup also seen a oem poulan single ring without a locator pin but I wouldn't recommend that one.