The possible factory issue with 026's?

[TJ the Chainsaw Mechanic]

Had an 026 in the shop that had been sitting, went through the fuel system and it fired and ran pretty decent. After some tuning I was running it and every time I would tip the nose Down the engine idle would either severely drop or it would kill the engine.
At first I thought I had set the metering lever to high so I checked with the gauge and it was right on the money. Lowered it a little for the heck of it....no change. Still, every time I'd tip the nose down it would die or idle severely dropped.
So I pulled the carb again and figured I'd check for fuel puddling, sure enough I could see a little ridge right at the cylinder edge of the intake port, And I could see a little gap and wall between the manifold and the intake port....perfect place for vapors to build up.

Is this common? A quick call to JD at stihl tech and I find this was the way they came from the factory. I think I finally have found why I can never get these to tune quite right. JD's "quick fix" is removing the cylinder and lightly grinding the ridge down on the intake port on the cylinder wall. Wish I had some pictures to better show what I am getting at.

Thoughts???

 

[jacob j.]

This has been an issue with 026s/MS-260s, and MS-440s/MS-460s. We talked to JD about it several times in 2004-2006 and the warranty fix for the 440/460s was for the customer to bring the unit in and then we'd remove the cylinders and grind the lip out. Stihl Northwest was reimbursing us for one hour labor on each unit. We were also doing new units we had on the shelf at that time but we would not be reimbursed until the unit sold.

 

[TJ the Chainsaw Mechanic]

This has been an issue with 026s/MS-260s, and MS-440s/MS-460s. We talked to JD about it several times in 2004-2006 and the warranty fix for the 440/460s was for the customer to bring the unit in and then we'd remove the cylinders and grind the lip out. Stihl Northwest was reimbursing us for one hour labor on each unit. We were also doing new units we had on the shelf at that time but we would not be reimbursed until the unit sold.

Interesting! Surprisingly enough my boss's never told me about that. Seems most purchasers haven't actually noticed this issue as in the time I have been at this shop we've never had to do that warranty repair yet. And this 026 was only brought it for a fuel system repair. Customer never mentioned any of these issues.
On the 460's was the repair up to a certain serial number? Both my 460's have never had this issue. Lip may be there though.

 

[Simondo]

Had an 026 in the shop that had been sitting, went through the fuel system and it fired and ran pretty decent. After some tuning I was running it and every time I would tip the nose Down the engine idle would either severely drop or it would kill the engine.
At first I thought I had set the metering lever to high so I checked with the gauge and it was right on the money. Lowered it a little for the heck of it....no change. Still, every time I'd tip the nose down it would die or idle severely dropped.
So I pulled the carb again and figured I'd check for fuel puddling, sure enough I could see a little ridge right at the cylinder edge of the intake port, And I could see a little gap and wall between the manifold and the intake port....perfect place for vapors to build up.

Is this common? A quick call to JD at stihl tech and I find this was the way they came from the factory. I think I finally have found why I can never get these to tune quite right. JD's "quick fix" is removing the cylinder and lightly grinding the ridge down on the intake port on the cylinder wall. Wish I had some pictures to better show what I am getting at.

Thoughts???

That is something I to have always noticed with that group of saw including the 024 av. Iv never understood the "Why" before. Played around with carbs and metering hight to with no real change. The only thing i found that helped a "Little" and stopped the saw falling right out was to run a very slight lower L adjustment and have idle at 3000 rpm so it would drop back to about 2400 after sitting the saw down for 30 seconds and tipping it on its nose. Under use of corse it never was a issue as you are on and off the trigger. Nice bit of onfo there TJ ...will have a closer look next time in inside one.

 

[TJ the Chainsaw Mechanic]

Might be the same issue I am dealing with on this long term 024 as well, I think I have only had ONE MS260 that actually ran without any issues. Rest seemed like they all had air leaks or fuel puddling. The air leaks seem common to.

 

[Simondo]

Might be the same issue I am dealing with on this long term 024 as well, I think I have only had ONE MS260 that actually ran without any issues. Rest seemed like they all had air leaks or fuel puddling. The air leaks seem common to.

I had a near brand new 024 av a bit back (I wanted a Datum to judge by)..it was ok if i tuned it like i put in the above post but in factory settings it would load up after sitting 30 seconds or so . Not stall out but could be close .

 

[DELETED (Struggle)]

so are you grinding the lip off the intake edge so it doesn't pool fuel then? I have a near mint 026 pro that did this and i shelves it so I could vac test it and a customer brought me one that did the same thing and it always passes vac and pressure test and my thought was it was pooling fuel in the intake as well.

 

[mtnwkr]

Now I want to go home and check mine.. Never noticed a problem though.

 

[Simondo]

A reference picture if anyone can come up with something would be excellent .

 

[Dustin4185]

My recently acquired 026 does this. I was thinking I had messed something up as a saw hack. Now I'm really going to have to hack into it to fix it!

 

[Basher]

All of the 026`s that pass through my hands, around 50+ by now all get that lip ground out to make the intake port almost symmetrical. I don`t have an idling problem or acceleration problem with this series of saws.

 

[Milkman31]

 

[stihl saws]

Interesting......

 

[Jughead]

hmm

 

[Duane(Pa)]

I have had two 026's. One does it, the other didn't. I thought it was fuel pooling in a pleat in the intake boot. I have turned screws for hours and have it working to suit me, but it requires a high idle as someone mentioned. I sure was bummed after thinking it was a problem with the 194 carb. I bought a new one and it did the same damn thing. I do like the saw, but it has some woes that other saws in it's class don't suffer. Oh, and tipping the nose down happens a lot when bucking firewood!

 

[Deets066]

Almost every stihl cylinder has a small lip on the bottom of the intake.

 

[Duane(Pa)]

@drf256 You have as much handle time as anyone on the 026. Any insight?

 

[TJ the Chainsaw Mechanic]

so are you grinding the lip off the intake edge so it doesn't pool fuel then? I have a near mint 026 pro that did this and i shelves it so I could vac test it and a customer brought me one that did the same thing and it always passes vac and pressure test and my thought was it was pooling fuel in the intake as well.

That's what JD told me to do, Thing is I also noticed a little gap on the inside of the intake boot where it clamps to the cylinder...I am almost certain that is a problem to.

 

[TJ the Chainsaw Mechanic]

A reference picture if anyone can come up with something would be excellent .

I'll see about getting one Saturday.

 

[Jughead]

this 024 doesnt have the lip

026
026
026