Stihl 024/026 ignition timing.

[Brewz]

Howdy folks.
I have just spent a day or 2 working over my 024 and 026.

The 024 was freshly rebuilt and ported but ran like a fat dog, my 090 had more zip off the mark.

The 026 was one of my first port jobs I did when learning and when I looked at the cylinder I thought..... oh my, how far I have come.
It needed a rebuild as the bearings and seals were old so it got torn down.

I found both had excessive blowdown up around 3o* as I ported them before I got a 90* tool.

Fixed this and they now both sit at 102/122/78

The 024 blows 200 psi, the 026 blows 220

They now run much better.

Now, the ignition timing.

I have the 024 running about 3/4 of a key advanced and it shows no signs of excess advance, in fact I recon it wants more.

The 026 is the same at about 1/2 key advanced and it feels like I'm starting a clamshell saw.

How much advance have others found these saws will take?

 

[drf256]

I've never pushed the 026 past .025-030 key.

@Basher found out that certain coils have different abilities to tolerate more advance. They may have a different curve, or that function may have broken.

Besides the usual popping, the 026 can have a lag off idle with too much advance and the wrong coil. The advance makes the saw want to be richer at idle, and then the fuel puddles somewhere in the intake tract. If you look at the intake port, there's a drop off just past the boot outlet on the floor-the intake port floor at entry is larger than the boot. I think it dribbles and collects there. Hit the throttle after some time idling, bog city.

I've found the most forgiving coil to be the Ducati coil. The winding area resin is deep blue, not reddish brown like the others.

Hope this helps tony.

 

[drf256]

This ones 25 off the key.

 

[Brewz]

Yes it does help mate.
It needs to have the idle super lean or it bogs after a bit of idle time.

How do you determine when the timing is best on these little saws?

 

[Brewz]

Here is the 026.
Im thinking its 4 stroking happily at 15720 RPM and can go higher.

 

[bikemike]

Here is the 026.
Im thinking its 4 stroking happily at 15720 RPM and can go higher.

That sounds like too much timing or getting air bubbles in the fuel line. It seems to bounce around at wot. Try it in some hard cuts the go wot no load and se where it's at

 

[bikemike]

This ones 25 off the key.

View attachment 73577

Stay away guys. He got the love glove on

 

[Brewz]

YEah she is a brand new build.
I got it warm and gave it the beans to see what it would do

It needs to be tuned in the cut but Im more interested in timing.

The bigger saws let you know by popping and breaking your fingers with the starter but Im not sure how to tell whats too much on a smaller saw

 

[Brewz]

Stay away guys. He got the love glove on

Thats a very VERY dirty tacho

 

[bikemike]

YEah she is a brand new build.
I got it warm and gave it the beans to see what it would do

It needs to be tuned in the cut but Im more interested in timing.

The bigger saws let you know by popping and breaking your fingers with the starter but Im not sure how to tell whats too much on a smaller saw

Well put it to wood tune it and watch your temps

 

[Brewz]

What I might do is drop the timing back to a .020 to .025 advance and see how it goes.
Now that I have corrected some timing issues they had, I need to take the timing back and start from scratch, see how they go

 

[bikemike]

What I might do is drop the timing back to a .020 to .025 advance and see how it goes.
Now that I have corrected some timing issues they had, I need to take the timing back and start from scratch, see how they go

What air filter do you have in the saw? That can makeep a night n day difference if needed you can get some fine nylon mesh from a crafts department and some hobby grade fuel proof CA glue and make a oem filter flow real good

 

[Brewz]

I have an aftermarket nylon filter on it as they flow better than the OEM flocked ones.
I plan to attack it tomorrow and glue on some fine SS mesh that's the same as on the OEM wire mesh filters.

 

[Brewz]

Made this from it, filters good, flows like it's not there

 

[bikemike]

View attachment 73588

View attachment 73589

Made this from it, filters good, flows like it's not there

View attachment 73590

Very nice

 

[MustangMike]

There are wire mesh filters out there, they cost a bit, but they are out there (on ebay).

 

[Basher]

There are wire mesh filters out there, they cost a bit, but they are out there (on ebay).

And also at your Canadian Stihl dealers supply chain. Wire mesh is all I run on my personal saws.

 

[Canadian farm boy]

026 wire mesh air filter PN is 1121 120 1611