Cat removal

[Beemerphile]

I thought the late model boxer exhaust flapper valve was in part to help pass noise standards.

It is. In part. Even with it the later boxers have more exhaust sound than the earlier ones. People who have removed the flapper have found not only more noise, but less bottom end.

 

[oldhack]

I ride with a guy who used to own an NC700 manual (mine is the DCT) and he had an Arrow de-cat and exhaust he purchased off e-bay. I know this because he used my work address to have the boxes delivered for safety. Riding his bike before his modifications helped lead me to buy my NC. When I asked about performance upgrades he told me about the Boosterplug that many of my friends own on their BMW's, and the de-cat exhaust he personally installed. The Boosterplug has made such a nice performance boost I don't care about a full exhaust, but he swears by the de-cat/exhaust. Said it made the bike breath much better and had much stronger top-end and smoothed-out the low end. He did not have a Boosterplug installed on his NC. Researching here and on other forums shows a very popular opinion on the de-cat like you said. If I do want to experiment with an exhaust upgrade, the de-cat will be the first thing I do. It's cheaper than an exhaust and will actually boost the power a little where an exhaust will only add noise. The fuel injection will automatically compensate for any minor changes without a problem, and that's pretty common knowledge.

 

[dduelin]

It is. In part. Even with it the later boxers have more exhaust sound than the earlier ones. People who have removed the flapper have found not only more noise, but less bottom end.

That last part is unintentionally funny to me. The late owner of BMW in Tallahassee, Dusty Rhodes, told me once that with advent of the oil heads "all those new boxers sound like an old man farting". I guess you had to be there.

 

[ld_rider]

Still, it's on the planet Earth where we all live and breathe. Removing the cat would be irresponsible.

Many (most) motorcyclists have no idea that they are riding one of the most polluting vehicles on the planet. A 2002 Yamaha YZF-R6 is responsible for as many hydrocarbon emissions in 1 mile as a Ford Expedition 4wd puts out traveling 28 miles and carrying 8 people (!).

EPA emission standards for newer Tier 2 motorcycles are a bit better, but not by very much. I'm thinking most Tier 2 motorcycles are responsible for about 10x the HC+NOx emissions of even the largest SUV and more than 15x the CO emissions.

 

[rogue17]

I ride with a guy who used to own an NC700 manual (mine is the DCT) and he had an Arrow de-cat and exhaust he purchased off e-bay. I know this because he used my work address to have the boxes delivered for safety. Riding his bike before his modifications helped lead me to buy my NC. When I asked about performance upgrades he told me about the Boosterplug that many of my friends own on their BMW's, and the de-cat exhaust he personally installed. The Boosterplug has made such a nice performance boost I don't care about a full exhaust, but he swears by the de-cat/exhaust. Said it made the bike breath much better and had much stronger top-end and smoothed-out the low end. He did not have a Boosterplug installed on his NC. Researching here and on other forums shows a very popular opinion on the de-cat like you said. If I do want to experiment with an exhaust upgrade, the de-cat will be the first thing I do. It's cheaper than an exhaust and will actually boost the power a little where an exhaust will only add noise. The fuel injection will automatically compensate for any minor changes without a problem, and that's pretty common knowledge.

Oldhack, this is much to my thinking as well. I read on another forum a while back about a guy who simply had his CAT removed, and his report matched what you've said. Ever since then I've been considering doing it myself. I just wander about the long term effects - if any.

 

[oldhack]

Oldhack, this is much to my thinking as well. I read on another forum a while back about a guy who simply had his CAT removed, and his report matched what you've said. Ever since then I've been considering doing it myself. I just wander about the long term effects - if any.

We've probably read all the same posts! No negative long term effects with any exhaust or high flow air filter with modern fuel injection today. The ECU (or ECM, whichever its called) will adjust for the changes. The only exceptions seem to be if you were to go crazy and modify the internals like a different cam, piston, etc... The fuel injection is a narrow band system so it can adjust for basic modifications, but nothing extreme. Have fun and report back!

 

[TigerDude]

without putting the bike on a dyno you really have no way of knowing what works. A lot of what people think is improvement is the placebo effect.

 

[L.B.S.]

Many (most) motorcyclists have no idea that they are riding one of the most polluting vehicles on the planet. A 2002 Yamaha YZF-R6 is responsible for as many hydrocarbon emissions in 1 mile as a Ford Expedition 4wd puts out traveling 28 miles and carrying 8 people (!).

EPA emission standards for newer Tier 2 motorcycles are a bit better, but not by very much. I'm thinking most Tier 2 motorcycles are responsible for about 10x the HC+NOx emissions of even the largest SUV and more than 15x the CO emissions.

While I'm not arguing your point, I will say though, that I bet there are a whole heck of a lot less 2002 R6's riding around compared to Ford Expeditions, and I would be really, really, surprised if any 2002 R6 owners put on 1/10th the mileage of an average SUV.

Again, not arguing, as I never remove the cats on any of my vehicles, but I think that even if all motorcycles are gross polluters compared to cars, the shear number of cars, and the miles driven (especially in rain/winter) and the fact that there are a zillion cars which *are* gross polluters, far, far exceed the overall end result of a motorcycle/car comparo.


I would dearly love to find out the pollutant amount put out by the average jet plane. I wonder how many decades of riding my hideously obnoxious emission terror 125cc cat equipped CBR commuter, it would take to match a day of flight time in a Prius owning couple's holiday, from New York City to Puerto Vallarta...

 

[davidc83]

While I'm not arguing your point, I will say though, that I bet there are a whole heck of a lot less 2002 R6's riding around compared to Ford Expeditions, and I would be really, really, surprised if any 2002 R6 owners put on 1/10th the mileage of an average SUV.

Again, not arguing, as I never remove the cats on any of my vehicles, but I think that even if all motorcycles are gross polluters compared to cars, the shear number of cars, and the miles driven (especially in rain/winter) and the fact that there are a zillion cars which *are* gross polluters, far, far exceed the overall end result of a motorcycle/car comparo.


I would dearly love to find out the pollutant amount put out by the average jet plane. I wonder how many decades of riding my hideously obnoxious emission terror 125cc cat equipped CBR commuter, it would take to match a day of flight time in a Prius owning couple's holiday, from New York City to Puerto Vallarta...

Hey, don't pick on us Prius owners (some of us even have Trump stickers on the back, along with Confederate flags and motorcycles are everywhere stickers)....

 

[johnakay]

not if you live here beemerphil lad.lol
https://www.facebook.com/miguelangel.morenatti.9/videos/10153982399259738/

 

[walawn]

Where is the cat located?


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Directly under the frame, middle of the bike. The exhaust flows from the headers, through the catalytic converter, and into and out of the silencer. I'm sure the fine honeycomb structure inside restricts flow. I sold Hyosung brand in GA and they had a mini-cat located just before the silencer. It was only a couple of inches wide, but helped clean up the emissions.

 

[670cc]

Directly under the frame, middle of the bike. The exhaust flows from the headers, through the catalytic converter, and into and out of the silencer. I'm sure the fine honeycomb structure inside restricts flow. I sold Hyosung brand in GA and they had a mini-cat located just before the silencer. It was only a couple of inches wide, but helped clean up the emissions.

My NC's catalytic converter is below the cylinders, not under the frame or in the middle of the bike at all. The NC doesn't have headers. There is only one exhaust outlet in the head. If anything could be called a header on this bike, it's a couple inches long because the converter is immediately after the exhaust outlet in the cylinder head.

I'd guess the converter would be a restriction, but so is the cylinder head design on the NC. And, restrictions are not necessarily a bad thing. Don't you think Honda engineers would have sized the cat to be appropriate for the air flow through the engine? What incentive would Honda have to install one that's too small?

 

[rogue17]

My NC's catalytic converter is below the cylinders, not under the frame or in the middle of the bike at all. The NC doesn't have headers. There is only one exhaust outlet in the head. If anything could be called a header on this bike, it's a couple inches long because the converter is immediately after the exhaust outlet in the cylinder head.

I'd guess the converter would be a restriction, but so is the cylinder head design on th NC. And, restrictions are not necessarily a bad thing.

Could you elaborate on that last paragraph 670cc?

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[RinconVTR]

Could you elaborate on that last paragraph 670cc?

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Certain flow restrictions and characteristics are designed into everything we drive on the street. If we were WFO on the race track all the time, then trying to remove every little restriction in the system would benefit, but only the very top end, and fluid dynamics still play a huge roll. Its entirely possible to reduce power at any given RPM range when adding free'er flowing mods.

As I mentioned in my first post, it typically takes many mods in combination to make any real power gains these days. There is so much development and fine tuning that goes into motors today, there isn't much to gain unless you pour the big $$$$ in.

So making everything free flowing with mega diameter pipes and

 

[rippin209]

While I'm not arguing your point, I will say though, that I bet there are a whole heck of a lot less 2002 R6's riding around compared to Ford Expeditions, and I would be really, really, surprised if any 2002 R6 owners put on 1/10th the mileage of an average SUV.

Again, not arguing, as I never remove the cats on any of my vehicles, but I think that even if all motorcycles are gross polluters compared to cars, the shear number of cars, and the miles driven (especially in rain/winter) and the fact that there are a zillion cars which *are* gross polluters, far, far exceed the overall end result of a motorcycle/car comparo.


I would dearly love to find out the pollutant amount put out by the average jet plane. I wonder how many decades of riding my hideously obnoxious emission terror 125cc cat equipped CBR commuter, it would take to match a day of flight time in a Prius owning couple's holiday, from New York City to Puerto Vallarta...

Apples and oranges we are talking about the pros and cons of altering the exhaust on motorcycles. Cat lowers emissions on motorcycles 5 to 10% at optimum temperatures on cars it's 20 to 40% and because they have more power to begin with they can mess with them allot more to clean up emissions. And jets actually burn pretty clean prop plans are allot worse. The number one polluter in the world is cargo ships. When processing crude oil they use everything all levels of gas and fluids. When all done they have a sludge almost as thick as play dough, 300,000 cargo ships in the world create more emissions then every car and coal powered power plant in the world, but pound for pound it's arguable. Hundreds of thousands of tons. If only they could be nuclear powered like the war ships

 

[670cc]

Could you elaborate on that last paragraph 670cc?

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No specific question was asked, so I'm not sure how to elaborate.

The NC cylinder head, with it's 1 into 4 to 4 into 1 intake/exhaust tracts, all intergrated inside the head, makes great simplicity for external components and compactness. One throttle body leads in, with no need to sync two throttles, and the one exhaust outlet allows direct coupling to the catalytic converter without lengthy header pipes. However, the angles and uneven length pathways are not the model for a high flow engine, which of course, the NC was never designed to be.

If simply removing exhaust restriction was the ticket for finding free horsepower, aftermarket exhaust companies would have a super easy job. Unfortunately, as was pointed out earlier (or was it a different thread?), they are apparently not always successful in actually increasing power just by having a more free flowing exhaust.

But this is all largely irrelevant since you indicated in an earlier post that you were looking mainly for more noise. On that point I couldn't make any judgement as to the cat's role in noise making. I'm really quite happy with the NC as is, with it's lack of noise.

 

[walawn]

My NC's catalytic converter is below the cylinders, not under the frame or in the middle of the bike at all. The NC doesn't have headers. There is only one exhaust outlet in the head. If anything could be called a header on this bike, it's a couple inches long because the converter is immediately after the exhaust outlet in the cylinder head.

I'd guess the converter would be a restriction, but so is the cylinder head design on the NC. And, restrictions are not necessarily a bad thing. Don't you think Honda engineers would have sized the cat to be appropriate for the air flow through the engine? What incentive would Honda have to install one that's too small?

View attachment 28871

My fault. I was thinking of another bike.

 

[walawn]

No specific question was asked, so I'm not sure how to elaborate.

The NC cylinder head, with it's 1 into 4 to 4 into 1 intake/exhaust tracts, all intergrated inside the head, makes great simplicity for external components and compactness. One throttle body leads in, with no need to sync two throttles, and the one exhaust outlet allows direct coupling to the catalytic converter without lengthy header pipes. However, the angles and uneven length pathways are not the model for a high flow engine, which of course, the NC was never designed to be.

If simply removing exhaust restriction was the ticket for finding free horsepower, aftermarket exhaust companies would have a super easy job. Unfortunately, as was pointed out earlier (or was it a different thread?), they are apparently not always successful in actually increasing power just by having a more free flowing exhaust.

But this is all largely irrelevant since you indicated in an earlier post that you were looking mainly for more noise. On that point I couldn't make any judgement as to the cat's role in noise making. I'm really quite happy with the NC as is, with it's lack of noise.

Does any company make a full exhaust for the NC??

 

[2brnut2b]

Does any company make a full exhaust for the NC??

Leo Vince and Arrow are both making slip-on and decat pipe.

 

[Hyperborea]

But this is all largely irrelevant since you indicated in an earlier post that you were looking mainly for more noise. On that point I couldn't make any judgement as to the cat's role in noise making. I'm really quite happy with the NC as is, with it's lack of noise.

If it's just more noise then the OP could consider this.

http://www.turbospoke.com/

[video=youtube_share;ZCvGGuN8a9k]https://youtu.be/ZCvGGuN8a9k[/video]