Lean or Rich?

[DGG]

A couple of us were discussing what happens to a chainsaw when the air filter becomes clogged and restricts the air flow.

Does this reduced air flow also lessen the fuel flow through the carb (venturi action) and make the saw run "lean"?

Or does the loaded up air filter have no effect on fuel flow and make it run "rich"?

Or does it have any effect at all?

Obviously it is best to run clean filters but I'm curious to hear from the wizards what happens to a saw that has a really loaded up air filter.

 

[ChuckinOhio]

In my experience the air filter being clogged makes the saw act real boggy, which leads me to believe that it makes it run overly rich.

If the saw is still running the impulse line is still feeding the carb regardless of airflow through the carb, and this would lead to a rich condition I believe.

At least I think thats how it works


Chuck

 

[Goat]

Chuck is right, if you have a clogged air filter that passes little air. You will pull a higher level of vacuum which increase your fuel flow. At idle, the increase in extra fuel will be much smaller than at WOT because of the smaller demand in air flow.

 

[troutfisher]

A couple of us were discussing what happens to a chainsaw when the air filter becomes clogged and restricts the air flow.

Does this reduced air flow also lessen the fuel flow through the carb (venturi action) and make the saw run "lean"?

Or does the loaded up air filter have no effect on fuel flow and make it run "rich"?

Or does it have any effect at all?

Obviously it is best to run clean filters but I'm curious to hear from the wizards what happens to a saw that has a really loaded up air filter.

Plugged air filter will make a saw run rich. The danger happens when you adjust the carb to compensate for this, then replace the air filter later. This will cause a lean condition.

 

[DGG]

Thanks to all!

I had remembered something about a clogged air filter causing the saw to run lean.

But this only after a carb adjustment.

Doesn't it seem that if you are going to go to the trouble of adjusting the carb you would clean or replace the air filter first?

 

[nytreeman]

def wouls run rich,clean it then first then adjust the carb

 

[Crofter]

The restriction of the clogged filter will lead to richening of the air fuel mixture admitted to the base but, and here is the catch, it reduces the volume of it. The reduced charge will not flush out all the exhaust and may even leave a vacuumn that sucks air back from the exhaust. This dilution will functionally lean the air fuel ratio of the trapped charge. On a four stroke there is no question; it makes it stinking rich. On a two stroke it is not so clear cut. Wonder what Lakeside thinks, where are you Lake?

 

[ChuckinOhio]

Holy Cow

A clogged air filter can cause SUCKBACK!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!




Chuck

 

[romeo]

Whats an "air filter"????????:hmm3grin2orange:

 

[thomas72]

I would think that it would make the saw run rich like partially choking it. On suck back, crank case pressure dictates that I would think. A saw will not run if the crank case pressure is not higher than the atmospheric pressure, which should be at least half of your cylinder compression.

 

[ShoerFast]

Whats an "air filter"????????:hmm3grin2orange:

Scotch-Brite or a Brillo-pad cut to the shape of the "thinggy"

 

[huskydave]

A clogged air filter can cause SUCKBACK!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!



That's why you need to mod your muffler it will prevent that! lol

 

[rahtreelimbs]

I'm Rich................ahhhhhhhh..................whos this guy Lean!!!

 

[Fish]

But would running over a 98 octane have any impact on this, with a
marvel mystery oil spritzer, and a splash of stabil?

 

[troutfisher]

Whats an "air filter"????????:hmm3grin2orange:

A felt device used to slow down your Bikesaw.