Stihl 261 mtronic air filter options

[huskyboy]

I hear that adding Frog Skins on the filter covers helps. More air comes in from the sides instead of from the front.

Note: My comments apply to the 440/460/660 saws, etc.. I think the 261/362 saws already stay pretty clean.

Yeah I think if you were to add holes to a air injection saw cover it would not be a benefit. Probably let more fines in. The air coming off the flywheel is pressurized and putting a hole in cover would just defeat the system I’d think?

 

[RI Chevy]

Only way to find out for yourself is to try it.

 

[Bilge Rat]

With no other changes to the saw the pressurized air would tend to exit the holes/ frog skins.
Is the air injection a method of getting enough air to the carb due to the close fitting cover or is it trying to supply slightly pressurized air to the carb ?
I don't see Stihl trying to supercharge the motor with this but more of a large supply of cooler air for the carb.

If you redirected the forced air out the side of the saw then put a tube thru the airbox opening, cut the end at an angle so the forced air would induce a vacuum in the tube.
This vacuum could draw air thru holes/ frog skins on the cover supplying carb with clean air.

Seems like the air injection and any mods to it are just creating turbulence around the filter.
Smooth airflow to anf thru the carb puts more air into the motor.

What is Stihl's thinking on what this air injection is supposed to do?

 

[RI Chevy]

My 261 with outerwear cover.
This cover is brand new. I only used less than a tank putzing around and already a hole. [emoji52]

 

[Bilge Rat]

It may be touching the cover. The running motor vibrations would cut a hole quick.

 

[RI Chevy]

Yup. I noticed that a fellow member posted a pic a while back that looked exactly the same.

 

[sawmikaze]

Yup. I noticed that a fellow member posted a pic a while back that looked exactly the same.

Mine has a hole now too but I'm gonna do some shaving with a dremel to remedy that.

Or maybe it's been there for a while and I just didn't notice it, last time I checked it over good when we were talking about it it didn't..idk..

 

[RI Chevy]

I just got done sanding the spot down that I think was rubbing on it.

 

[huskyboy]

With no other changes to the saw the pressurized air would tend to exit the holes/ frog skins.
Is the air injection a method of getting enough air to the carb due to the close fitting cover or is it trying to supply slightly pressurized air to the carb ?
I don't see Stihl trying to supercharge the motor with this but more of a large supply of cooler air for the carb.

If you redirected the forced air out the side of the saw then put a tube thru the airbox opening, cut the end at an angle so the forced air would induce a vacuum in the tube.
This vacuum could draw air thru holes/ frog skins on the cover supplying carb with clean air.

Seems like the air injection and any mods to it are just creating turbulence around the filter.
Smooth airflow to anf thru the carb puts more air into the motor.

What is Stihl's thinking on what this air injection is supposed to do?

I’m sure there engineers spend a lot of $ and time in R/D. They also have computer created designs. I don’t think we should try to be smarter than the engineers. Improve what’s there...not rewrite the book imho. I also think they have to consider the epa regulations in designs.

 

[Bilge Rat]

Yes they know why they have this air injection.
Now what is their main reason for doing this?

Just trying to understand the design.

 

[huskyboy]

Yes they know why they have this air injection.
Now what is their main reason for doing this?

Just trying to understand the design.

Because the old non air injection filter setup gets dirtier faster. The flywheel flings the heavier chips away by centrifugal force. The injection tube pickup the cleaner air nearest to flywheel fins then routes to airbox. Simple really. Filter stays cleaner for longer.

 

[CR888]

My air injection port is plugged closed. I am still only getting fines in the filter pleats. Not much has changed. Although things may when I put some 1/2" holes in the shroud above the rear handle.

 

[Duane(Pa)]

Yes they know why they have this air injection.
Now what is their main reason for doing this?

Just trying to understand the design.

Keeping up with Husky (whom had it first). It's called inertial seperation in the airplane world.

 

[sawmikaze]

I just got done sanding the spot down that I think was rubbing on it.

Here's a weird one...

My OE 261 which I've used the most with the outerwear has no holes.

My new 261 does...figure that out.

My 241 has no holes, I use it a good bit.

I'm sitting at my bench looking at this *s-word as I type this.

 

[drf256]

I wonder if the air inlet to the carb box from the flywheel supplies enough air To the filter area.

The felt filter can be gutted and covered with Uni foam, they sell it in sheets.

That's why I put a Frogzskin on Jeffs cover.

 

[drf256]

Nothing wrong with the stock pleated filter BTW.

 

[RI Chevy]

Ryan, are your 261s both the same version? Or is 1 a version 1 and 1 a version 2?

 

[Duane(Pa)]

Nothing wrong with the stock pleated filter BTW.

Jousting with windmills...

English idiom that means attacking imaginary enemies.

 

[sawmikaze]

Ryan, are your 261s both the same version? Or is 1 a version 1 and 1 a version 2?

1 and 2

 

[RI Chevy]

Which one cut the outerwear?