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Discussion Starter · #1 · (Edited)
Before I gut or ditch the CAT...

I have an AKRO slip on exhaust, and before I choose the method of getting rid of the CAT, I want to present the three options. Number one is concern that in doing so, the H2 will be too loud for track use, which I plan regularly.

Option 1: Cut the CAT out add a pipe (with tapered sections to mate with the exhaust. remove the restrictor valve, and silence the idiot light.

Option 2: Cut and gut the CAT, remove the restrictor valve and replace as is.

Option 3: Cut the CAT, and bore it out and insert a pipe through it, weld in place, remove the restrictor valve. This seems like a logical solution and will allow for smoother exhaust flow.

If I can keep the decibel level equal to my BMW S1000RR at 109 I will be happy, 129 like the H2R is not acceptable.

Anyone who has dealt with this problem and came up with a good solution, thanks in advance for posting. There may be more options than I thought of as well.

Rhody...
 

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I have an AKRO slip on exhaust, and before I choose the method of getting rid of the CAT, I want to present the three options. Number one is concern that in doing so, the H2 will be too loud for track use, which I plan regularly.

Option 1: Cut the CAT out add a pipe (with tapered sections to mate with the exhaust. remove the restrictor valve, and silence the idiot light.

Option 2: Cut and gut the CAT, remove the restrictor valve and replace as is.

Option 3: Cut the CAT, and bore it out and insert a pipe through it, weld in place, remove the restrictor valve. This seems like a logical solution and will allow for smoother exhaust flow.

If I can keep the decibel level equal to my BMW S1000RR at 109 I will be happy, 129 like the H2R is not acceptable.

Anyone who has dealt with this problem and came up with a good solution, thanks in advance for posting. There may be more options than I thought of as well.

Rhody...
3 is the best
 

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My thoughts, in bold after your points.


Option 1: Cut the CAT out add a pipe (with tapered sections to mate with the exhaust. remove the restrictor valve, and silence the idiot light. This is the easiest, get a Guhl flash and pick up 23 hp and you don't have to worry about the idiot light. This is what I would do if I did not have to worry about class rules or emission laws. Someone (Brock!!!) needs to make a simple pipe to go in here for off-road use. I thought my guy would do it, but after I explained the market, he declined.

Option 2: Cut and gut the CAT, remove the restrictor valve and replace as is. This is more involved, you probably want to go into the cat from the bottom and cut out a rectangle area along the seams. Getting the honeycomb material out is a pain in the butt. It takes time, be patient. Reweld the bottom piece and it looks like stock - all legal. This is what I did on my production race bike - it had to appear stock.

Option 3: Cut the CAT, and bore it out and insert a pipe through it, weld in place, remove the restrictor valve. This seems like a logical solution and will allow for smoother exhaust flow. This would be the optimum method. It will take more time and be more complicated. After getting the honeycomb material out, you won't want to go to this extra effort. There is already a diverter piece in there, so the tubing really isn't necessary. If you saw what a convoluted path the exhaust takes in the stock muffler, you wouldn't even consider adding the tubing. This proves beyond a shadow of a doubt how good muffler science is today as it is hard to improve on the factory design.


Back in the 70's, anyone with a gas torch and some tubing could make headers that would improve on the factory effort. My buddies at D&D exhaust in Ft. Worth were geniuses on how much horsepower they could extract. Now it isn't so simple. Those guys in Japan who were young enthusiast are now seasoned engineers at Kawasaki, Yamaha, Honda and Suzuki, and they know their stuff. I doubt any of them like to see the latest ad that says "pick up 15 horsepower on your production Yamazukikawanda" with a simple exhaust change, it just tells them that they left a lot of power on the table if they had done their homework. I understand the noise and emissions part, but so do the engineers, they know the test requirements and can build a muffler that is quiet enough at XXX rpm to pass the test and then able to scream to 13,000 rpm when it counts.

The best reasoning for cleaning up the cat is that we don't know how well it will hold up to the continuous load of a breathed-on motor. We have to assume that bikes that are raced will run somewhat hotter and owners may want to use race gas too. My fabrication guy thought for sure we would pick up power by gutting the muffler and cat, but all we got was about 15 more decibels. I thought for sure after seeing the red glowing exhaust of bikes on the dyno that the cat would melt and I wanted to be ahead of the problem. In a way I wish I had gone ahead and melted the **** thing down to prove my point, but it is done and I am moving on.

Last, without knowing how loud your Akro is, can you pack some additional material in there to quiet it down? I can't imagine them testing the decibels at 13,000, don't they just have you drive by at 60 and check the levels? I'm sure you wanted the Akro for the weight savings, but will that muffle the sound well enough normally?
 
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All I did was pull the muffler off. Looks like a GP exhaust with a little nub coming out by your heel. Based on dyno reports thus far it sounds like the only advantage to pulling the cat is losing weight and adding noise. With the cat still in place and no muffler the thing sounds awesome. It's in the 'just right' Goldilocks zone.

So it sounds like the best option for HP and sound is;

Option 4; install a lithium ion battery to offset the weight of leaving the cat on ($160 no core), pull off the ugly muffler. Call it a day.

The only caveat is that it kinda melts your shoe a little if you run it hard for a long time. If you must, Jardine makes a great GP slash cut slip on that's short, straight and looks the most like the H2R can I've found this far - and it'll redirect the fire from your heel. I wonder if I can use that as an excuse for speeding; "sorry officer but I was trying to put out the fire on my shoe".

:)
 

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I can't really think of a reason to 'disable' the servo valve and retain the factory Cat chamber by gutting it and welding a pipe in there...you'd just be adding weight.I'd just(and did)remove that cat altogether and install a midpipe and aftermarket lightweight muffler.The sound did increase somewhat...but certainly not anywhere near where you'd be not allowed to track it.
 

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At this point, why should anyone mess with the CAT at all? Removing it doesn't help make any more HP, without the muffler it's still really loud and the weight savings can be offset. All you're doing by removing it is wasting money on a hatchet job and making it impossible to get it past smog somewhere down the road. More I consider it, it almost seems like Kawasaki designed the system so you could yoink the heavy muffler and skip the aftermarket looking for more power. I was frustrated initially by them welding it on but now it makes perfect sense.
 

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Cat is hideous and heavy, not friendly with leaded race fuels. There is not such thing as "offsetting" the weight of the cat. It's either there, or not. Ideally you want the lighter battery AND the weight loss from no cat. Full system will be the best solution for power and weight loss. But if you can't afford that, removing the cat make sense, imo....I would cut the whole thing out and have new midpipe fashioned.
 

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Hey Warp12, I know that Brock said 9 extra horses with the DNA, so he decided to be a dealer for it. What exactly did he get for DNA,
flash, with a stage 2 complete exhaust with or without baffle?
 

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Hey Warp12, I know that Brock said 9 extra horses with the DNA, so he decided to be a dealer for it. What exactly did he get for DNA,
flash, with a stage 2 complete exhaust with or without baffle?
The last dyno I saw was 262 STD, I believe. I think the DNA added more in the upper-midrange, than at peak? Not sure, but I believe there is a chart somewhere around here....
 

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Cat is hideous and heavy, not friendly with leaded race fuels. There is not such thing as "offsetting" the weight of the cat. It's either there, or not. Ideally you want the lighter battery AND the weight loss from no cat. Full system will be the best solution for power and weight loss. But if you can't afford that, removing the cat make sense, imo....I would cut the whole thing out and have new midpipe fashioned.
I like solutions leading to Cat removal but the few of us H2 owners living in California don't have the option of removing it.
 

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I like solutions leading to Cat removal but the few of us H2 owners living in California don't have the option of removing it.


Just cut it and gut it, picture below.
 

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Discussion Starter · #14 ·
Thanks for your replies, I am going with option #3 , will gut the CAT and have a custom pipe (2 piece) inserted, when the bike is finished, I will post pics and maybe a video.

Rhody...
 

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Thanks for your replies, I am going with option #3 , will gut the CAT and have a custom pipe (2 piece) inserted, when the bike is finished, I will post pics and maybe a video.

Rhody...
Just out of curiosity, why? What does it buy you other than a failed smog test?
 

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I've bought a Termignoni muffler that has a cat built on the inlet side of it.
Should have it installed next week hopefully.Probably won't have the cat left,but it is stamped as having one.Removable db killer also.
Hello, is it for H2?
 

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Just out of curiosity, why? What does it buy you other than a failed smog test?

When you modify a motor, you are running the risk of damaging the converter. The converter relies on receiving the proper mix of exhaust gases at the proper temperature. Changes to the mixture or the temperature of the exhaust gases can lead to failure. Hot rod engines and converters do not usually do too well. Unless you have a perfect tune that is close to the design that the cat was designed for, you will run the risk of a clogged, or melted unit. Keep your bike stock, or just add a pipe, don't worry about it, but if you modify the tune very much you will have problems.
 

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Hello, is it for H2?
No,not specifically made for the H2.
I went to my States Termignoni supplier/representative and basically made him pull every can he had out of the box.
This one is for a Z750 I think.It,to me anyway was what I was looking for on size,shape and the convenience of the db killer as well as the cat stamp.
You can buy one the same without the cat,I just wanted the stamp as well.The cat end will be gone when it's fitted.
 

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Where I get my inspection, it doesn't matter. Just personal preference, simple as that.


Rhody...
I still don't get it. You're still going to have the weight and the unsightly box, you get no HP and you're disabling an expensive unit you or the next guy are gonna have to replace. If you go trade it in, it's illegal for a dealer to sell a bike missing the OE smog equipment so they're going to nick you the replacement cost. Running modified isn't going to harm a titanium honeycomb heater or melt it or clog it. It won't even notice. 'Personal preference' is usually based on something; sound (makes near as no difference), looks (will be the same), weight (probably more after the inserted pipe and 5 pounds of rod needed to weld it closed) or horsepower (zero difference).

In your mind, what do you think after you write the check? You're going to spend a bunch of money ruining a cat for literally nothing. I'm dying to understand your process.
 
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