MS270 intake torn. Again. And other questions

[JackBurton]

Hi all.
Short version is, Ive got an MS270 with a torn intake boot. Second one in two years. Already ordered that, but not sure thats the only issue.
Longer version is, Some time back I posted an issue my neighbor was having getting his MS270 repaired. Turned out to be the intake boot. That was about a year and a half ago I believe.
Anyway, a few weeks ago, as he was finishing up his Winter wood stockpile, he started having issues again.
This time it was very odd.
Saw ran great, except when tilted forward. Then it would stumble and die.
I did some research here and other places and everything I found seemed to point to the carb or fuel line. Fuel like LOOKS good, but until I pull it, I cant check it very well.
My guess was the carb, since I couldnt get it running good at idle. The screw is maxed out, but limit caps are in place. Based on that, I figured it might be a good candidate for a rebuild.
Neighbor thought what the heck, and was going to order the kit, but the dealer wanted to know what number was on the carb, and he didnt know. I took it off to get the number, and noticed the boot.
As I said, this is the second boot in less than 2 years, and the saw doesnt get abused, so Im not sure what is going on.
Is this a common thing for these to go that quick?
Is there something he can to do prolong the life of the new one?
Would it help to put some kind of silicone lube on the end by the cylinder?
--my thought here is that if its getting twisted, maybe that will let it move slightly to alleviate the issue. Maybe not?

My other question is, given its age, and it has been well used, but not nearly worn out, would it be wise to go ahead and rebuild the carb while Im at it? I can get the kit cheap online, so its considerably cheaper than the dealer.
I initially thought Id just do the intake and see how it went, but Id rather not tear into it again if I dont have to. I dont mind helping a neighbor out when I can, but Ive got my own stuff going on too!

Any help or thoughts appreciated!

 

[HarleyT]

Usually a bad av mount or similar.

 

[HarleyT]

I haven't watched this yet......

 

[HarleyT]

 

[Ozhoo]

Intakes get torn most often when operators yank the saw out of a bind... or the AV system is worn. Here's the ipl & shop manual to help you out. I'd do gaskets and diaphragms on the carb.

 

[Goofaroo]

Are you saying that the Stihl engineers mounted the intake boot to the cylinder and the chassis in such a way that it is stressed by the AV system?

 

[dswensen]

Are you saying that the Stihl engineers mounted the intake boot to the cylinder and the chassis in such a way that it is stressed by the AV system?

I think it would be more accurate to say that a worn AV system, and/or yanking on a saw that has been pinched in the cut, creates more movement of the bar/engine vs the carb box than the saw was designed for - thereby allowing the boot to tear.

 

[lone wolf]

Are you saying that the Stihl engineers mounted the intake boot to the cylinder and the chassis in such a way that it is stressed by the AV system?

No it breaks when the mounts have too much wear and allow movement beyond what is intended therefore tearing the boot! Also pulling on the saw like really hard.

 

[Andyshine77]

Yup what they said! Pulling on the saw too hard when the saw gets pinched and or bad AV mounts.

 

[BangBang77]

Is it apparent when an intake boot is torn? As far as I know I've never torn one but I have pulled fairly hard to get a saw out of a pinch.

Does the saw run funny? Not respond to the LA carb needle adjustment? Idle funny?

 

[dswensen]

Is it apparent when an intake boot is torn? As far as I know I've never torn one but I have pulled fairly hard to get a saw out of a pinch.

Does the saw run funny? Not respond to the LA carb needle adjustment? Idle funny?

If the tear opens up while it is running, it will suck in air through the tear, and since the boot is after the carb in the intake system, it will draw more air (some through the carb, and some through the tear) with the same amount of fuel, creating a lean condition. This will, at best, create a poorly running saw, and at worst, damage your P/C.

 

[BangBang77]

If the tear opens up while it is running, it will suck in air through the tear, and since the boot is after the carb in the intake system, it will draw more air (some through the carb, and some through the tear) with the same amount of fuel, creating a lean condition. This will, at best, create a poorly running saw, and at worst, damage your P/C.

Understood. Is it readily noticeable when this happens? Can you hear it or feel in the saw?

 

[pioneerguy600]

Happens very often on the 170 and 180 series saws, they have too soft of AV rubbers when new and all the flexing only makes them move more and further than the boot can stretch, tears are common in them.

 

[Tom B.]

If it's been starting & running fine except for the intake boot & AV mounts, I'd say get the parts & fix it.
A: You have the familiarity of it.
B: It's a fairly inexpensive fix.
C: It doesn't owe you or the neighbor anything. It's paid for itself a long time ago, This is bonus time.
<edit> Get a carb kit anyway, they're not pricey (even a Walbro kit). You'll probably need it eventually anyway.

 

[lone wolf]

Just pull on the handle and

Understood. Is it readily noticeable when this happens? Can you hear it or feel in the saw?

Just pull on the handle as to separate it,
see if the rpm's change to confirm a ripped boot in most cases.

 

[BangBang77]

Just pull on the handle and

Just pull on the handle as to separate it,
see if the rpm's change to confirm a ripped boot in most cases.

Thanks man!

I don't suspect any of mine at the moment but just curious how someone would know if they had a torn boot.

 

[lone wolf]

Thanks man!

I don't suspect any of mine at the moment but just curious how someone would know if they had a torn boot.

RPM'S change or saw may die depends on size of leak..

 

[JackBurton]

Wow. Thanks everyone!

Ill have a look at replacing the AV mounts. Worth doing to keep this issue at bay.

Thinking about it, I do know his saw got "bumped" by a tractor and broke the top handle. Id imagine if any one thing did it, that would have.

 

[stihl86]

Happens very often on the 170 and 180 series saws, they have too soft of AV rubbers when new and all the flexing only makes them move more and further than the boot can stretch, tears are common in them.

I agree. That family is aimed at a very occasional user. MS 270 is not a rugged saw. It’s is made for comfort and to “ensure that the user has a pleasant and rewarding wood cutting experience” . But that type shouldn’t have a saw in their hand.
The mounts are one step up from oatmeal. Too bad, because it has a very good engine in it, and will cut very well.

 

[Tom B.]

I agree. That family is aimed at a very occasional user. MS 270 is not a rugged saw. It’s is made for comfort and to “ensure that the user has a pleasant and rewarding wood cutting experience” . But that type shouldn’t have a saw in their hand.
The mounts are one step up from oatmeal. Too bad, because it has a very good engine in it, and will cut very well.

Well that`s good to know. Thinking I should order some AV mounts & intake boot just because.