Stealth Exhaust
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From: Land of Sun, Sand and Thorns - AZ
RE: Stealth Exhaust
Good deal. Like I said before 'zapitbullseye' already took a saw to the entire stock exhaust to show the guts and where everything really is!
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RE: Stealth Exhaust
You guys are flat out wrong. Believe what you want to believe. Why don't you look up USFS web page & see how they check for a spark arrestor. It is in the end, where the shiny stainless steel band is. It is a Krizman spark arrestor--look it up. It looks nothing like a baffle with holes
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From: Land of Sun, Sand and Thorns - AZ
RE: Stealth Exhaust
Okay let's see a photo of it.
Side Note: The only way your going to get a spark pass the cat convertor and all those baffles in the stock exhaust is if you're running on wood chips and not gas
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RE: Stealth Exhaust
A "spark" is nothing more than a hot piece of carbon. Carbon builds in the exhaust & eventually flakes off. These hot carbon particles can go out the exhaust & start fires. Knowing this you can see how the only place that makes sense for it is at the end. If it were anywhere else it would not catch all the carbon that can flake off the muffler!
The cat has nothing to do with it. Zap claims he never saw the cat but law states it has to be there starting in model year 2006 so I still maintain it was never found. A typical motorcycle cat lookslike ahoneycomb structure with mixing straw sized tubes in it.
There are two main types of spark arrestors, Krizman & screen. There is a third kind also I believe but it is not used on the KLX. All the aftermarkets are screen. They can plug with carbon & require cleaning--which is why virtually all japanese bikes use Krizman. Look at any aftermarket spark arrestor--its a screen at the end.
The Krizman style (OEM) looks like a stationary turbine. It routs the exhaust through the turbine then it hits the very end plate of the muffler--alll around the outlet hole. It then flows back around & out the opening. This motion of the exhaust causes all carbon particles to drop out of the exhaust air.
Don't believe me:
1. There is a cleanout plug at the end of the muffler. This cleanout is where all the particles drop out in the Krizman arrestor. You remove the plug, start bike, & it blows the arrestor out clean.
2. Look in a stock exhaust, I bet you see the turbine structure. I could see it on my 300EX, XR650L, & KLX 300 muffler. I never bothered looking in my 250S muffler--it wasn't on long.
3. The method the USFS uses to check for a spark arrestor is to stick a wire in the exhaust outlet & it MUST hit the spark arrestor within a certain distance. They use 1/8" wire to check for krizman types, for screens they use a 0.024" wire (meaning the screen must be fine enough to not let a 0.024" wire pass through---that is very small & why they can easily clog--especially on two strokes).You stick your drill in--the first thingyou drill through is the sparky. Now you do not pass inspection & are ticketed for modification to no sparky.
4. Here is the KLX300 muffler--note the Krizman turbine where I said it was. The 250 S is similar.
This is the inlet (header side)
This is the outlet--the bolt hole is the end of the muffler where the "butt plug" bolts on.
See the same bolt hole? See the cleanout plug?
I have seen a pic of an entire 300 muffler cut exactly in half, the whole thing, but i cant find it.
5. Krizman operation:
http://www.planetklx.com/techtips/no-butt-plug-reqd.htm
6. Bottom line, its a Krizman, Krizmans are all the same, they are all at the end--they use the endplate of the muffler as a componet of the spark arrestor.
The cat has nothing to do with it. Zap claims he never saw the cat but law states it has to be there starting in model year 2006 so I still maintain it was never found. A typical motorcycle cat lookslike ahoneycomb structure with mixing straw sized tubes in it.
There are two main types of spark arrestors, Krizman & screen. There is a third kind also I believe but it is not used on the KLX. All the aftermarkets are screen. They can plug with carbon & require cleaning--which is why virtually all japanese bikes use Krizman. Look at any aftermarket spark arrestor--its a screen at the end.
The Krizman style (OEM) looks like a stationary turbine. It routs the exhaust through the turbine then it hits the very end plate of the muffler--alll around the outlet hole. It then flows back around & out the opening. This motion of the exhaust causes all carbon particles to drop out of the exhaust air.
Don't believe me:
1. There is a cleanout plug at the end of the muffler. This cleanout is where all the particles drop out in the Krizman arrestor. You remove the plug, start bike, & it blows the arrestor out clean.
2. Look in a stock exhaust, I bet you see the turbine structure. I could see it on my 300EX, XR650L, & KLX 300 muffler. I never bothered looking in my 250S muffler--it wasn't on long.
3. The method the USFS uses to check for a spark arrestor is to stick a wire in the exhaust outlet & it MUST hit the spark arrestor within a certain distance. They use 1/8" wire to check for krizman types, for screens they use a 0.024" wire (meaning the screen must be fine enough to not let a 0.024" wire pass through---that is very small & why they can easily clog--especially on two strokes).You stick your drill in--the first thingyou drill through is the sparky. Now you do not pass inspection & are ticketed for modification to no sparky.
4. Here is the KLX300 muffler--note the Krizman turbine where I said it was. The 250 S is similar.
This is the inlet (header side)
This is the outlet--the bolt hole is the end of the muffler where the "butt plug" bolts on.
See the same bolt hole? See the cleanout plug?
I have seen a pic of an entire 300 muffler cut exactly in half, the whole thing, but i cant find it.
5. Krizman operation:
http://www.planetklx.com/techtips/no-butt-plug-reqd.htm
6. Bottom line, its a Krizman, Krizmans are all the same, they are all at the end--they use the endplate of the muffler as a componet of the spark arrestor.
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RE: Stealth Exhaust
Illistrated version. Carbon particle laden exhaust we will call it = red. the turbine forces it to flow out to the end cap. Partles fall out = yellow.Pressure forces it the only place left to go--out the end=green. You can see why this is a restrictive system on the 250S--it has a tiny exhaust outlet--like what, 3/8"? The 300 has 1.5". Anything you do to increase this disables the arrester though. Which is why you always see me proclaiming the stock 250S muffler is hopeless.
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From: New Glasgow, Nova Scotia, Canada
RE: Stealth Exhaust
Okay, so the fact that I drilled out that turbine-looking plate essentially disables the spark arresting abilities of my bike? right? I am not going to lose any sleep over it, but thanks for clearing it up..I still don't think a spark is going to get past the first tube that is capped at the end..it's in there quite a piece, andby the time a hot spark bounces around inside there to get by that tube, it will have lost its ability to burn anyway (in my opinion)..I don't have a problem with carbon build up anyhow
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From: W. Oregon
RE: Stealth Exhaust
http://www.motorcycledaily.com/12oct...forestfire.htm
http://www.motorcycledaily.com/14oct...karresters.htm
The Associated Press reported yesterday that an 18 year old central Washington resident would be billed for the costs of fighting an August wildfire which consumed thousands of acres of forest and burned one home. The rider is believed to have started the fire while riding off-road on a bike without a spark arrester.
Many of us have ridden our MX bikes somewhere other than a closed course at least a few times, and so our first reaction might be to sympathize with the rider. However, looking at the fire from the perspective of a Washington state taxpayer, or from that of the family whose home was destroyed, you might not feel so sympathetic.
Off-road riders among us should take this as a reminder to make sure their bikes are equipped with a spark arrester before riding in areas that pose a risk of fire (which includes pretty much all of my native Southern California). Those of you who ride four-strokes might also consider the addition of aftermarket pipe guards (like those made by E-Line) which offer more coverage than the stock items. Every four-stroke owner knows how hot the head pipes can get; imagine dropping your four-stroke in an area thick with dry brush.
Check out the full AP article here.
Many of us have ridden our MX bikes somewhere other than a closed course at least a few times, and so our first reaction might be to sympathize with the rider. However, looking at the fire from the perspective of a Washington state taxpayer, or from that of the family whose home was destroyed, you might not feel so sympathetic.
Off-road riders among us should take this as a reminder to make sure their bikes are equipped with a spark arrester before riding in areas that pose a risk of fire (which includes pretty much all of my native Southern California). Those of you who ride four-strokes might also consider the addition of aftermarket pipe guards (like those made by E-Line) which offer more coverage than the stock items. Every four-stroke owner knows how hot the head pipes can get; imagine dropping your four-stroke in an area thick with dry brush.
Check out the full AP article here.
After the article I wrote on Tuesday (Ride Without Spark Arrester, Get Bill for $10 million), I got email from a few readers who expressed doubt that a motorcycle without a spark arrester could start a fire. Others assumed that the sparks being 'arrested' came from backfires, and that only four-strokes or improperly-jetted two-strokes would create this discharge.
In a quest for further information, I came across the Spark Arrester Guide (Published by the National Wildfire Coordinating Group, and sponsored by the US Departments of Agriculture and the Interior). Here is an excerpt from the section entitled "Basic Definitions and Test Standards":
Exhaust Particles - All internal combustion engines produce exhaust particles which are predominately carbon with contaminates. These particles originate from deposits formed on the internal surfaces of the engine or exhaust system and, depending on their exact origin, may be expelled at temperatures in excess of 3,000 degress F. Depending on the nature of the contaminates, these particles are capable of glowing or sometimes flaming combustion. When expelled through the exhaust system into the atmosphere, the combustion process may continue or even be accelerated during flight. Such particles, if larger than 0.023-inch in diameter and at temperatures of 1,200 degrees F are capable of igniting cellulose materials on contact.
A Spark Arrester is a device which traps or pulverizes exhaust carbon particles to a size below 0.023-inch in diamter, as they are expelled from an exhaust system. Trap type spark arresters must have a method for removal of accumulated carbon particles. Most spark arresters generally perform in the high 90 percent spark arresting effectiveness range.
As anyone who has ever rebuilt a two-stroke top end can tell you, the piston and parts of the cylinder and cylinder head often have carbon and other gunk built up on them. Four-stroke engines can contain, and expel, similar deposits. Like the report says, small particles of this gunk may detach and be expelled through the exhaust system. Having been in contact with very hot parts of the engine, these particles can themselves be at a very high temperature when expelled. So a spark arrester is important insurance for any bike that will be ridden near trees or brush.
In a quest for further information, I came across the Spark Arrester Guide (Published by the National Wildfire Coordinating Group, and sponsored by the US Departments of Agriculture and the Interior). Here is an excerpt from the section entitled "Basic Definitions and Test Standards":
Exhaust Particles - All internal combustion engines produce exhaust particles which are predominately carbon with contaminates. These particles originate from deposits formed on the internal surfaces of the engine or exhaust system and, depending on their exact origin, may be expelled at temperatures in excess of 3,000 degress F. Depending on the nature of the contaminates, these particles are capable of glowing or sometimes flaming combustion. When expelled through the exhaust system into the atmosphere, the combustion process may continue or even be accelerated during flight. Such particles, if larger than 0.023-inch in diameter and at temperatures of 1,200 degrees F are capable of igniting cellulose materials on contact.
A Spark Arrester is a device which traps or pulverizes exhaust carbon particles to a size below 0.023-inch in diamter, as they are expelled from an exhaust system. Trap type spark arresters must have a method for removal of accumulated carbon particles. Most spark arresters generally perform in the high 90 percent spark arresting effectiveness range.
As anyone who has ever rebuilt a two-stroke top end can tell you, the piston and parts of the cylinder and cylinder head often have carbon and other gunk built up on them. Four-stroke engines can contain, and expel, similar deposits. Like the report says, small particles of this gunk may detach and be expelled through the exhaust system. Having been in contact with very hot parts of the engine, these particles can themselves be at a very high temperature when expelled. So a spark arrester is important insurance for any bike that will be ridden near trees or brush.