A Stihl 024 that i Converted to a 026

[Definitive Dave]

Technical Area
024 and 026 info thread
024_4r.pdf
download or open
about 3/4 of the way down you will come to tech bulletin T.1.85
it outlines the differences with identifying measurements between 024 and 024 Super

 

[odin]

Here's the link to the tech thread - http://opeforum.com/threads/024-and-026-info-thread.2064/#post-143707

 

[odin]

Oh, and thanks Dave. I printed those all off a few days ago. Now I've just got to find the time to read through them.

 

[Definitive Dave]

I didn't realize that several of the scan sets had duplicates in them
I need to get off my butt and do all the others I have in stacks around here.
I am a tech bulletin junkie

 

[T.Roller]

My 026 I built was with a 024 case. Ran great till a tree *b-word slapped it! Lol

 

[Aaron5161]

Thought I would bring up the past! If an 024 is a 30mm stroke and an 026 is a 32mm stroke. (Correct me if I'm wrong.)...

Can I not take an 026 top end and delete the base gasket?

A friend mentioned that I could try it and check the squish and see what happened.

This is coming from an old redneck with a tore down 024 and an 026 top end hanging out. Any thoughts?

 

[Tpagel]

It will work but it will be a poor running saw unless you change the crank too.

IIRC you will need very large solder to check the squish on the 30mm crank.



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[Aaron5161]

Ok. I'm probably going to end up ordering an 024 top. I just wanted to ask about the theory behind it.

 

[Tpagel]

I have a good one if you need


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[Aaron5161]

I think the cylinder will fine. I might try to get by with just a piston.

 

[MustangMike]

The 024 S has the same stroke as an 026 and can be converted by just changing the P&C, but not the regular 024.

 

[drf256]

The 024 S has the same stroke as an 036 and can be converted by just changing the P&C, but not the regular 024.

If you swap out the covers for 026 covers. Otherwise you'll need to cut the two top rear fins off of the 026 jug.

 

[sawtalk81]

I'm interested in the results as well, mostly how he got there.

I plan on a few conversions myself.

@Tpagel discovered that the crank centerline was different in the case on the 024 vs. 024S/26. He tried to add an 026 crank and found that the crank throws stuck out of the case too much. As the stroke is 30mm vs 32mm (1mm in each direction), I suspect that Stihl simply lowered the crank centerline 1mm in the Super/026. I haven't proven this yet.

If my suspicions are correct, an 026 piston and jug should bolt right on to a regular 024, the timing will just be wonky. With the shorter stroke, an 026 jug on the 024 case should result in a much lower exhaust roof by degrees and way too much intake. The shorter stroke should make it a little rpm monster.

I hope the OP posts how he did it. I will get into one this fall. It's got an MS260 tank/covers and an 026 recoil. There's a chance that case is actually a super case.

do you have an ipdate on your build 026

 

[drf256]

Many 026 threads here. Never did the crank swap.

 

[sawtalk81]

It will work but it will be a poor running saw unless you change the crank too.

IIRC you will need very large solder to check the squish on the 30mm crank.



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what carank would you use destroke?

 

[sawtalk81]

Many 026 threads here. Never did the crank swap.

028s jug 024 case?

 

[drf256]

028s jug 024 case?

No, none that I know of.

You need a certain amount of case volume to make a saw run well. The 024 crank is the destroked crank for the build. I still haven’t figured out if the standard 024 crank in the larger 026 case takes up less volume than an 026 crank and would provide more case volume for the build.

With the 30mm crank, the 46mm bore makes it 49.8cc. With the standard 026 crank, it’s over 53cc which is out of most classes for racing.

 

[sawtalk81]

No, none that I know of.

You need a certain amount of case volume to make a saw run well. The 024 crank is the destroked crank for the build. I still haven’t figured out if the standard 024 crank in the larger 026 case takes up less volume than an 026 crank and would provide more case volume for the build.

With the 30mm crank, the 46mm bore makes it 49.8cc. With the standard 026 crank, it’s over 53cc which is out of most classes for racing.

Very detailed write up thank you very much.I personally think the volume your looking for with the 024 crank would almost be spot on. if not very close. keep me updated if you find the answer.

 

[sawtalk81]

I have a good one if you need


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Yes I'm in need of one i can PM with the details

 

[sawtalk81]

My 026 I built was with a 024 case. Ran great till a tree *b-word slapped it! Lol

With a 026 crank? or did you leave it stock?