spark arrestors

[guff]

i just thought i would get more feedback if i changed the heading..................... i did a muffler mod to my ms260 and left the arrestor screen intact, after i had opened her to 3 times the original size............i have installed a walkerized 440 and 066 mufflers and they have no screens at all..........so, what causes your so called spark, is it carbon from running a rich mixture?? and what's the story on the muffler suckin in wood chips?? someone help me out...............thanks..............guff...and should i put screens in, will they restrict flow, any danger.....just hit me with everything you can speculate on...thanks again...........guff

 

[eyolf]

The spark arrestor screen is pretty important if you're cutting in the west...the woods can be pretty dry out there, it just takes a spark to set the duff on fire. I've heard that the USFS gets downright ugly about contractors using only stock, EPA-approved equipment with everything intact.

I don't know if its so important in NY. Somebody will say it is, though. Maybe when all the leaves are down and things are very dry.

Any engine spits out an occasional spark, and two strokes even more so...keep in mind that as the piston uncovers the exhaust port at high rpm, the fuel mixture is still burning, or at least the gases are still at extremely high temps. A particle of anything shaken loose into this stream of hot gas will soon be maybe 1500 deg or more. The most common particles will be deposits from the exhaust port or muffler...not necessarily carbon, but that's what we all call it.

I don't know anything about mufflers sucking in sawdust, and I think it sounds a bit unrealistic...There may be a brief period when the pressure wave inverts and begins to have enough strength to pick up a bit of dirt, but I don't think so. I've never heard of it anywhere but here. Just because I don't know about it doesn't mean it can't happen.

Actually, hot gas is one of my specialties

 

[Crofter]

Exhaust screens

I don't know how much of a reverse flow there might be either Eyolf but there is a problem around here with mud dauber wasps. They look for a hole and haul in mud etc. I also had an experience with gas welder in a shed where I also had a crib of corn. When I went to crank it it wouldnt turn over. I pulled the plugs and one cylinder was chuck full of kernels that a mouse had carried in. That is a pretty long shot I know but I like to have the screens in if for no other reason. Some screens are quite tight weave and reduce area by close to 30% but I dont know if it actually reduces flow 30%. I have found stainless screen in food seives that is a fairly good source.

Frank

 

[JimL]

Every once in a great while I get a something in that has a mud dobber nest in the muffler. Usually it is in leafblowers?!? Not sure why.

 

[Tony Snyder]

Those mud dobbers love gun barrels. Similar probably applies to some chainsaw mufflers.

 

[eyolf]

I've seen many a mud dauber nest, but not yet in a chainsaw muffler. They like holes under about 1/2" in diameter.

I enjoy growing a garden, and learned that the mud dauber preys on some pesty garden pests. In the hope that they go after the darn corn earworms I despise, I've been drilling 3/8" holes in pieces of wood and hanging them under the eaves of my outbuildings in the summer. I get lots of daubers, but seems like I notice fewer things with mud nests in them in my barn and sheds.

Maybe it's kinda like welfare...when the government supplied subsidized housing, the "Hoovervilles" went away. Still got plenty of earworms and them durn white moths and green worms on the broccoli, though...

 

[johncinco]

I think I see where this discussion was carried over to the other thread about mufflers. I will just say after asking and reading about this so many times I have decided to leave the screens off when I do it. I dont cut when it is dry anyway. Seems I am always out in the rain or snow!

Your thinking way incorrectly on the corn borers. You should welcome them and plant more corn for them. Then in the fall, go out and "harvest" the worms, put them in little plastic cups from your restaurant supply store, and sell them to all the ice fishermen. At $1.50 for 12 little worms, you can eat out at the best restaurant in town, order steak and corn, and still have money left over.