Stihl 026 clean up

[Likesaws]

I have a new to me Stihl 026 that I am cleaning and restoring. Very low hour saw still has machine marks on piston and cylinder. Was wondering what most recommend for a stock. I rebuilt the carb and will open up the muffler. Do you recommend a timing advance key way and how much should I take off for stock saw.
Any other recommendations.
Thanks

 

[drf256]

They respond to muffler mods quite well. I add a deflector to the flywheel side of the muffler can and sometimes close off the front factory outlet.

Timing advance (TA) usually works quite well, but some saws develop an off idle bog with the advance. Make sure there isn’t a lip between the intake boot and the intake port snout-fuel puddles there. The TA requires richening of the idle mix, then the pooling gets worse and the hesitation occurs. That’s the theory at least. Take around 25 thou off the key-that should bring you to around .053 thickness.

You cannot delete the base gasket on any of the 44mm jugs. That’s been my experience, YMMV. They usually wind up in the .007 squish range without the gasket.

You want the WT194 carb for the best airflow and a metal AF helps a bunch. You can always swap out to flocked in dry and dirtier conditions.

They are nice little compact powerhouses. They can’t beat up an MS261, but they are much more compact and nimble.

 

[Likesaws]

Thanks Doc
Another question can the worm gear for the oil pump drive be changed to the clutch driven type or is there a shaft length difference?

 

[Agent Smith]

Another question can the worm gear for the oil pump drive be changed to the clutch driven type or is there a shaft length difference?

You need the ms260 pump, clutch bell and worm gear. Shaft length is the same from 026 to 260. Same crank

 

[whitesnake]

They respond to muffler mods quite well. I add a deflector to the flywheel side of the muffler can and sometimes close off the front factory outlet.

Timing advance (TA) usually works quite well, but some saws develop an off idle bog with the advance. Make sure there isn’t a lip between the intake boot and the intake port snout-fuel puddles there. The TA requires richening of the idle mix, then the pooling gets worse and the hesitation occurs. That’s the theory at least. Take around 25 thou off the key-that should bring you to around .053 thickness.

You cannot delete the base gasket on any of the 44mm jugs. That’s been my experience, YMMV. They usually wind up in the .007 squish range without the gasket.

You want the WT194 carb for the best airflow and a metal AF helps a bunch. You can always swap out to flocked in dry and dirtier conditions.

They are nice little compact powerhouses. They can’t beat up an MS261, but they are much more compact and nimble.

By 44mm jugs you are including 44.7 I assume? How about a pop up piston if one is looking for a compression bump? I’m assuming even though bore size is the same a 261 piston won’t work in a 026? I see highway makes a pop up for 261’s. Red barn makes one for the 026 but I have no idea on quality. I would think if you put on caber rings and better clips you should be ok? This obviously is for someone who doesn’t have the ability to machine base and squish and is looking for a “bolt on” bump in compression. I have a couple 026’s in boxes I should turn into a winter project if I can find some time. Time is the key word lol.

 

[Likesaws]

You need the ms260 pump, clutch bell and worm gear. Shaft length is the same from 026 to 260. Same crank

Ok thanks I did not realize that I had to change the pump to.

 

[drf256]

You need the ms260 pump, clutch bell and worm gear. Shaft length is the same from 026 to 260. Same crank

And the washer and crank sleeve. A lot of work and not a lot of gain.

 

[drf256]

By 44mm jugs you are including 44.7 I assume? How about a pop up piston if one is looking for a compression bump? I’m assuming even though bore size is the same a 261 piston won’t work in a 026? I see highway makes a pop up for 261’s. Red barn makes one for the 026 but I have no idea on quality. I would think if you put on caber rings and better clips you should be ok? This obviously is for someone who doesn’t have the ability to machine base and squish and is looking for a “bolt on” bump in compression. I have a couple 026’s in boxes I should turn into a winter project if I can find some time. Time is the key word lol.

44.7 aren’t 44mm. The 44.7 have bigger squish, so with no gasket, they usually come in at 17 squish.

026 and 260’s are domed pistons with matching chambers. They have a tiny, maybe 5mm squish band. One can sand the band out with an old piston and adhesive backed sand paper and then cut the base if needed. Can match the chamber to the piston dome that way. Can get pretty good compression on the 44mm that way, even if you can’t cut the base.

Most people port them by cutting both the piston dome and chamber flat.

A 261 is a different animal completely. It has a heavy strato piston with a flat top. . They share virtually no parts.

 

[whitesnake]

44.7 aren’t 44mm. The 44.7 have bigger squish, so with no gasket, they usually come in at 17 squish.

026 and 260’s are domed pistons with matching chambers. They have a tiny, maybe 5mm squish band. One can sand the band out with an old piston and adhesive backed sand paper and then cut the base if needed. Can match the chamber to the piston dome that way. Can get pretty good compression on the 44mm that way, even if you can’t cut the base.

Most people port them by cutting both the piston dome and chamber flat.

A 261 is a different animal completely. It has a heavy strato piston with a flat top. . They share virtually no parts.

If one were replacing a top end do you think a 44.7 is worth using over a 44? I’ll have to pull mine out and look at them again I think they were ok to clean up. Just curious what your thoughts were on the 2 different top ends.

 

[drf256]

Use what you’ve got. Both OEM are very good jugs.

No big difference in jugs. The 44.7mm piston skirt is the same width as the 44mm skirt. IIRC they both max out at under 65% of bore width.

They do well from porting and the flat band/crown cut because they need less exhaust duration. The flat cut allows one to drop the exhaust roof more.

The 44mm allows the use of a Husky 246 piston. That takes a bunch of work, but with the centrally located single ring pin, one can add fingers. The skirts are wider, so a bigger exhaust as well. The quickest one I built was via this route. Base gets kinda thin with this route.

 

[drf256]

246 piston in an 026 44mm jug.

 

[drf256]

Here is an NWP jug that I sanded the band and chamber on. This is easy to do for most and will probably get you in the 020 squish range. Taking some more from the chamber, one can hand sand the base down using some sandpaper on a piece of glass.

 

[drf256]

Here are some different 026/260 jugs and different chambers.

The second chamber picture is a stock “red lever” old style chamber. You can see the small band on the edge. The entire band and chamber matches the piston dome curve. The band is only a few thousands thick. You can see how 200psi is pretty easy on these. With the flat band cut, they usually run in the 240psi+ range. There really isn’t a need for a popup, nor is it feasible with the curved chamber.

 

[redline4]

If one were replacing a top end do you think a 44.7 is worth using over a 44? I’ll have to pull mine out and look at them again I think they were ok to clean up. Just curious what your thoughts were on the 2 different top ends.

I can tell you with 100% certainty if you are not paying attention and assemble a "box of 026/260" and you put a 44mm piston in a 44.7mm jug and you try to start it, it wont...oops..