gutting the cat

modmaster_imp

Running like a top
Thread starter
Actually I love both of my cats but I would like to know if anyone has ever been able to gut the inside of their catalytic converter. Could you access it by reaching in from the outlet and perhaps knock the insides out with a good sized bar? Just wondering if anyone has tried yet.

modmaster
 
Maybe we should change the title? lol ..although it is catchy and makes you look.
 
Why would you want to? Cats are not very restrictive. My Moto Guzzi had Cats in the exhaust canisters. I replaced those with after market cans without Cats and there was no difference in power output.....verified on a dyno.

My nephew ran a straight pipes from the Cats on his Mustang 5.0 thinking that the Cats would be enough to muffle the exhaust. He was wrong. The exhaust was as loud as just attaching the pipes to the header.
 
And I thought we were going to talk violins.

I would think there would be little to gain by gutting the cat but I'm sure it could be done.
 
I thought there was a post in the past of a member taking out the guts of the cat.


2014 CB1100 DLX
2013 CB1100 Std
1990 BMW K75 RT
 
His last visit was Jan. 29.
 
kDiqq_imp said:
Hm. My ears were burning. ;)

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Good, then maybe you can answer this?:

I can see from your photos that the CAT honeycomb material is the full diameter of the collector tube, but approximately how long is it?

Is it short enough that you could maybe hog it out (or just open it up significantly) with a long drill bit from the outlet of the collector tube, or is there too much offset in the outlet tube to do that?

I don't want to take work away from you, but shipping my header to you and back from Canada would be very expensive.
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Post Edit: I guess I should have re-read your old post that I provided the link for! ;)

The CAT material was almost as long as the collector tube so hogging it out from the small end of the offset outlet tube would be practically impossible, hence your modification method.
 
Thread starter
Thanks to kDiqq for his link and posting about how he dealt with gutting his cat. To show that no actual cats were harmed in the making of this thread I am including two very live pictures of my cats.
modmaster
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Sadly (or thankfully) I am a dog person.

The catalyst is bonded to the sides of the pipe and is of VERY sturdy steel. Seriously. Even with one end cut off, it was difficult to remove. Luckily I don't survive off my skilled header hacking so I can give tips on removing it. The key is making a clean cut as far back as possible and somewhere where a weld doesn't look odd.

Once you have the header open, the catalyst in the small end will simple slide out. In the long end, you'll have to start with using a drill and punching as many holes in it as you can.

The holes will allow the material to compress as you scrape it away from the ID of the header. Because the catalyst material is so strong, it will peel away cleanly as you chisel it off.

Now, if you have a welder, this part is easy. Reattach the entire exhaust back on the bike. I used wood to brace things while I figured out where pieces needed to go. Using a 316LSi or similar high-grade SS filler and trimix gas, tack in place. Unbolt, finish welding using overlayed tacks. The stainless is runny and easy to burn though. Plus this controls heat tinting.

After one heat cycle, the color will return to uniform!

If you don't have a welder, find a quality fabricator to weld it back up. Just make sure you use a good quality bandsaw to open it up and account for about 1/16 kerf when having it welded together again :) it should be cheap to find a local fabricator!

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Thread starter
Thanks for your reply kDiqq. I really appreciate you posting back to me. Very decent of you considering you don't even own your CB anymore. Nice group of guys on here. I don't have the ability to weld but I always wanted to and admire those who have the skills and equipment to do so. So it looks like this mod will have to come off my list. It's a shame because I have a Staintune, a TSR air filter cover, an oxygen sensor eliminator, and I am getting my ECU reflashed, and that would have been a good mod to balance out all of them. Oh, I am a dog person too.
modmaster
P.S. I promise I will not post any more animal pictures, after these 2 anyways.

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0726e2cbe7b148697bb4bb63e11beca4.jpg~original
 
modmaster_imp said:
Thanks for your reply kDiqq. I really appreciate you posting back to me. Very decent of you considering you don't even own your CB anymore. Nice group of guys on here. I don't have the ability to weld but I always wanted to and admire those who have the skills and equipment to do so. So it looks like this mod will have to come off my list. It's a shame because I have a Staintune, a TSR air filter cover, an oxygen sensor eliminator, and I am getting my ECU reflashed, and that would have been a good mod to balance out all of them. Oh, I am a dog person too.
modmaster
P.S. I promise I will not post any more animal pictures, after these 2 anyways.

2683a1c0fc519178bb54f68c399fdf3b.jpg~original
0726e2cbe7b148697bb4bb63e11beca4.jpg~original
Mod,

I have a perfect stock header with the cat removed. It's polished and ready to use. I was going to use it on my bike but after installing my PC-5 the bike ran so well with the cat that I didn't want to re-tune with less back pressure. I'll sell it for $250 plus shipping but I won't be home to box it up for about a week.

Chip
 
kDiqq, is it right you no longer have your CB?
 
Correct! I bought and sold a few times since then... having an issue finding the perfect bike right now. Current dual sporting a WR250R, getting ready to put 500 miles on it this weekend. We shall see what the future holds :)

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kDiqq_imp said:
Correct! I bought and sold a few times since then... having an issue finding the perfect bike right now. Current dual sporting a WR250R, getting ready to put 500 miles on it this weekend. We shall see what the future holds :)

Sent from my STV100-1 using Tapatalk
Quite a few of us have rowed that boat lol
 
Thread starter
Chip I'm just waiting on you to let me know if your still going to sell me your gutted cat headers. I sent you a PM a few times but I haven't heard anything from you. I thought this might get your attention. I'm waiting with money in hand.

modmaster
 
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