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Spark arrestor screens... can you remove em?

Started by Great Big, March 13, 2009, 09:43:39 AM

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Great Big

Is there any benefit of removing the screens?  Better exhaust flow?  Risk of fire?

Any performance gain?
Brandes Farm Trophy Whitetails Est. 1999
Managing for Quality Whitetails in Southeast Ohio

ErikC

  We can't run without arrestors here, and the fire danger is so high I wouldn't anyway. There is less restriction without it, but cleaning them from time to time helps a lot. If it's hot and dry, I wouldn't risk it.
Peterson 8" with 33' tracks, JCB 1550 4x4 loader backhoe, several stihl chainsaws

Polly

my problem with them is when you shut down the engine and they pop like a shotgun ,i have converted two engines back to dual exhaust using the old type mufflers that have a 1 inch threaded inlet ,this adapts easily to your manifold engine pipes ::) ::) :)

SwampDonkey

I have never removed the screen in my saw, but it's a homeowner type saw. Not a  saw used in the bush for a living. That being said, the screens come off our brush saws. I don't know anyone that leaves them in. It wouldn't be so bad if they didn't gum so quick. And don't accuse me of not knowing my gas mix like the last guy. If so, than I guess us brush cutters are some dumb lot.  :D
"No amount of belief makes something a fact." James Randi

1 Thessalonians 5:21

2020 Polaris Ranger 570 to forward firewood, Husqvarna 555 XT Pro, Stihl FS560 clearing saw and continuously thinning my ground, on the side. Grow them trees. (((o)))

ErikC

  What's your climate? SD has pretty high humidity, but where I am is is under 10% all summer and most of fall, with huge amounts of fuel. I would fire someone if I found out they had removed it, because if the USFS found out they'd cite us, and if we started a fire we would pay the bill. If I lived in a different climate I would probably remove it too.
Peterson 8" with 33' tracks, JCB 1550 4x4 loader backhoe, several stihl chainsaws

Al_Smith

I won't say go for it .However in northern Ohio you would have an awfully hard time setting a woods on fire with a chainsaw .

An yes as a normal rule they will run better but of course they get kind of loud  if you strip the baffles .Just pulling the screen doesn't make them bark that much though .

Now as far as reworking a muffler there must be ten thousand threads on evey web forum on the net pertaining to same .

SwampDonkey

On a Husky spacing saw, you have to take the muffler off to get the screen out. But, none-the-less after about 6-10 replacements of that screen to clean the thing the threads are going to be all stripped out. Is DNR going to give you a new saw when the muffler starts dangling on there. NO! A spacing saw runs more hours on high rev than most guys on a chain saw. Your not holding the throttle on when you walk around choosing your next tree to saw or waiting for the tree the fall for limbing. A spacing saw covers about every square inch of ground for up to an hour each tank. The tank is usually bigger on a spacing saw as well, so a lot more fuel runs through it in a day.
"No amount of belief makes something a fact." James Randi

1 Thessalonians 5:21

2020 Polaris Ranger 570 to forward firewood, Husqvarna 555 XT Pro, Stihl FS560 clearing saw and continuously thinning my ground, on the side. Grow them trees. (((o)))

Jim Spencer


SwampDonkey

errmm brush saw to some.  ;D No, not those home owner weed whackers. ;) We call'm spacing saws or thinning saws up here 'cause that's how they are used.  ;D



Here's a Stihl FS550. The screen on it bolts on to the outside with a metal shield over it. The bolts still strip out on the muffler as the exhaust and rain corrodes it. The screens bugger up fast and you loose production. The newer Huskies have the tank that goes out the tube and holds a lot more gas than this, but are a little less powered than the old professional Husky saw and this Stihl. Echo now is the biggest brush saw, power wise.
"No amount of belief makes something a fact." James Randi

1 Thessalonians 5:21

2020 Polaris Ranger 570 to forward firewood, Husqvarna 555 XT Pro, Stihl FS560 clearing saw and continuously thinning my ground, on the side. Grow them trees. (((o)))

Al_Smith

 If I could post a picture on this site I would show you all something you actually would not believe .

Last spring I did a simple port job on a Stihl 038 AV .The saw had a carboned up piston top which I cleaned before reassembley .

Just yesterday I lifted the top to cut down the cylinder base after maybe 30-40 hours of running time .That piston had absolutely no carbon ,looked new .

I attribute that to two things .First 32 to 1 mix and secondly a gutted muffler .

So say what you will about oil and do what you like about mufflers .I know first hand as do others . :)

arojay

I agree about the oil and mufflers, but I also think that octane has an effect.  I used to run regular gas and my screens would carbon up, along with some other undesirable conditions.  Since I started running gas over 91 ron I have none of these problems.  More complete combustion.
440B skidder, JD350 dozer, Husqvarnas from 335 to 394. All spruced up

SwampDonkey

I never use regular gas in my saws either, was recommended not to by the dealers. I use higher octane.
"No amount of belief makes something a fact." James Randi

1 Thessalonians 5:21

2020 Polaris Ranger 570 to forward firewood, Husqvarna 555 XT Pro, Stihl FS560 clearing saw and continuously thinning my ground, on the side. Grow them trees. (((o)))

Polly

my sthl manual says use medium grade 89 octane ,it sure makes it start better ;) ;)

SwampDonkey

I use mid grade also, I recall the dealers saying the high test had no added benefit. Clean my air filter on my brush saw every day and I never have engine trouble until the saw in warn out. I'd say 200 acres on a  brush saw is pretty dang good, 300 is even better. :D Most are pretty much done after 200. Some only cut 100 and kept as spare, because some guys buy a new one regardless. I have two saws now that have cut less than 100 acres and no trouble to start right today if I wanted to. I plan on using them both this summer. Two saws and I should cover twice the ground eh? ;D :D
"No amount of belief makes something a fact." James Randi

1 Thessalonians 5:21

2020 Polaris Ranger 570 to forward firewood, Husqvarna 555 XT Pro, Stihl FS560 clearing saw and continuously thinning my ground, on the side. Grow them trees. (((o)))

zackman1801

one in each hand? :D

As far as spark arrestors go, if you do remove em make sure you dont get caught. The US forest service will write out fines for the removal of the spark screens. I cant see that it would make a TON of difference removing a 1 inch piece  of metal screen for the muffler to breath better, if you need to get your muffler breathing better do a muff mod on it, but i would still add my own screens for it then too. The question is, is it really worth it if you do start a big fire in the woods? 
"Improvise, Adapt, OVERCOME!"
Husky 365sp 20" bar

Al_Smith

 Nobody said you couldn't put the screening back in .Just make the hole larger .That's simple enough .

SwingOak

When I bought my 262XP back in '94 I asked the guy if there was any potential problems I should know about, and he said that as soon as I got home I should take the screen out. He said most of the saws he got in for service just had a clogged screen, and there was no reason to have it in there unless I was going to be cutting on USFS land, and I wasn't. I've never seen a spark come out of the saw - ever.

Now, my dad has a 1961 Homelite that looks like the 4th of July when it runs. He tells me it never started any fires, but it's easy to see how it could happen.

Al_Smith

Quote from: Lurcherman on March 16, 2009, 08:39:09 PM
Now, my dad has a 1961 Homelite that looks like the 4th of July when it runs. He tells me it never started any fires, but it's easy to see how it could happen.
I think that's probabley typical of a low compression saw engine .Some of those were only 6.5 to one comp ratio .

IndyIan

I run my 372 with the screen off and I pryed the flap over the exhaust hole up a bit, I can't say I noticed a huge difference in power but the saw did run a little bit leaner so I think it gained a bit more hp.  I also just turned the screen around and left it on the saw so I could find it again if it gets really dry here.
I do see the occaisional spark come out of the exhaust when cutting into the evening so the screen is there for a reason.
Ian

zackman1801

If your going to open up a muffler or do things to make it flow better you have to richen up your carb. If you dont give the saw some more mix its going to burn itself up by running lean. Just some things to think about before you start gouging holes in the muffler. But it will gain you more power and speed.
"Improvise, Adapt, OVERCOME!"
Husky 365sp 20" bar

Al_Smith

 The whole thing is pretty simple if you think about it .

You rework a muffler so the saw engines moves more air though it .More air requires more fuel .It takes fuel to make power .

Some folks get the misconcieved idea that because the saw sounds like it is running faster after a muffler job to just let it go that way .They never see what it does in the wood nor for that matter even know what a lean run sounds like . Those are the ones that get fried  in time .

Polly

i thought reworking the muffler relieved back pressure in the exhaust , thus causing the engine to use less fuel and increase the horse power  ::) ::) :)

Rocky_J

Polly-
More fuel, not less. Otherwise, everything else in your statement is correct.

Al_Smith

In a way I can kind of see ole Pollys predicament .

You have to look at an engine as nothing but a self propelled air compressor .If you increase this air pump to move more air it will also move more fuel . It also makes it less efficient but that's the price of power .

Without going into a bunch of mumbo jumbo most saw engines do not even come close to the amount of power they are capable of producing . Just a simple removal of the screen will improve just about any of them .Reworking a muffler will increase it further .

Then you get to reworking the engine .I could go further but that would be getting a tad off the subject of muffler screens . That said though I did stick one back together I reworked and the results were quit pleasing . 8)

Polly

this is kind of off topic but i had a 1990 four cylinder honda that got about 32 miles pr gallon now thanks to uncle sam installing all the good engine and exhaust modifications the new 4 cylinder honda is supposedly getting 30 mph , now as for as i know basicly all uncle sam done to make this so called improvement more or less was to increase the engine exhaust pressure along with recirculating the exhaust gas , please correct me if i am wrong  ;) ;)  :) to have a friendly discussion someone has to take an opposing view i am noted for doing this  :D :D :D

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