Cat removal on my '17 ST " how to"

lukasteam

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Hello guys ,
This my quick tudor/experience for the folks that want to get rid of the catalytic converter from the stock headers . I did it and can't be happier . First I saved the money because Arrow headers cost $300 online , second I got better results than I expected . Motor runs so much smoother and cooler , I also noticed the bike now revs faster and so effortless and that's just what I noticed right away after a quick couple hour test ride .
Bike is not much louder maybe 3-5db's , but a little deeper , but I still have a stock can and thats another choker that I need to change in a near future .
Also stock headers ID is the same as Arrows , stock headers pipes are stainless , just the part where cat sits is carbon steel and once the cat is removed that cavity becomes like a little gas expansion chamber which Arrows don't have and that might help the exhaust gas flow even more , but don't count me in that since I'm not the expert and I can't claim any gains from this mod .
 
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lukasteam

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So , let's start !!!
First thing before you tear in to this , get yourself a pair of new exhaust headers gaskets . Second get the right tools which will make a job so much easier and quicker .
You gonna need a die grinder like this IMG_20190822_134849846.jpg
Make sure that you use the thinnest disk that you can get since cutting is going to take some metal out , but don't worry too much because the walls of the chamber where cat sits are pretty thick , so when you weld you have plenty of metal to fill in the gap .
 

lukasteam

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We going to cut right in the middle of the stock weld . Mark the middle of the weld with the marker all around , so it's easier to follow the line when cutting .
NOW , VERY IMPORTANT - mark the part that we going to cut at least in two places , so you can line them up correctly when it's time to weld the pieces back together . You can use a marker or a scraper like I did .
IMG_20190817_135234301_HDR.jpg
Now that you have everything marked the right way , double check and start cutting .
Some folks suggested to wear a mask like a respirator while working on this because the put all kinds of chemicals when they making converters and breathing this dist can be toxic .
IMG_20190817_135349886_HDR.jpg
 

lukasteam

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Time to remove the tumor ...
Put one piece of pipe in a wise cat side up . Use aluminum or hard rubber jaw protectors , so you don't scratch the surface .
Grab a hand drill and drill pilot holes as close to the cat chamber inner walls as possible all around the inner circle of the pipe . Once that's done follow up with the larger diameter drill like you see in the picture . Cat material is soft and the drill will go straight through , easy job . IMG_20190817_143558333_HDR.jpg
At this point just grab the cat material with the needle nose pliers and pull it out .IMG_20190817_141238500_HDR.jpg
Do the same thing with the other half of the pipe .
 

lukasteam

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Time to clean up the inside of the pipe now that we have cat material out .IMG_20190817_141244279_HDR.jpg
This is what I used to clean the insides of the both half's
IMG_20190822_134125756.jpg
First I went with the stone and once all the cat metal matterial was gone from the walls I followed up with the sand paper to polish it out a little bit .
IMG_20190817_145656221_HDR.jpg
 

lukasteam

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Insides are clean and shiny , tumor is gone time to put things back together . Lighn up your marks and tack both pieces back together . It's better if you have an extra set of helping hands to hold both pieces on the marks while you tacking it together .
IMG_20190817_150420577_HDR.jpg
IMG_20190817_150431706_HDR.jpgIMG_20190817_150428362_HDR.jpg
Guys that don't know how to weld or don't have a welding machine at home , don't get discouraged from doing this , just take both pieces to a good muffler shop I'm sure they will be more than happy to weld it for you for couple bucks .
 
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lukasteam

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After tacking both pieces together double check everything , make sure everything is nice and straight , now you can start welding.
IMG_20190817_151939947_HDR.jpg
IMG_20190817_151948456_HDR.jpg
After first bead , I thought a little about a the vibrations on the bike and decided to lay another bead over the first one .
IMG_20190818_224740162_HDR.jpg
Im sure it would have been perfectly fine with only one bead because the exhaust headers and can mount to the frame on rubber grommets , but I'm just paranoid perfectionist like that .
Let me know how you guys like it once you do this mod on your ST and any questions just ask . Good luck !!!
 

lukasteam

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I had no idea how full the cat was. It's a wonder any gas gets through.

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Yeah , you would be amazed how much smoother the motor runs . That cat also restricts the hot exhaust gas flow right under the engine and the heat rises right into the motor raising the operating temps .
 

lukasteam

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I would take to a metal fab shop or muffler place . Our bikes are our pride and joy . If you don't feel too confident with HB welder take to the shop IMO .
 

Fennellg

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More air flow means leaner. His reflash should have helped. Wondering my self if it is enough or is a piggy back controller like power commander V neeeded.?
 

Lux

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Great job and very nice write up. Are you planning on gutting the stock silencer also? I wonder how restrictive the stock can is? Those aftermarket silencers are crazy expensive.
 

squarebore

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Sunshine Coast, Queensland, Australia
How would this effect the fuel air ratio if you stay with stock Ecu?
I thought the ecu adjusted for changes in air density such as climbing to 10,000ft. Surely the cat doesn't make that much difference. The pressure at 10,000ft is only 70% of sea level pressure. That is a big change and the ECU adjusts for that. Keen to know the answer if anyone has it.

Also read removing the cat can lead to worse fuel economy and loss of low end torque. Lots of pros and cons on the net. Not sure what is true.

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GearheadGrrrl

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You might want to think about the long term consequences before you delete emissions equipment- You may find that dealers won't work on your bike or take it in trade on a new one.
 

Fennellg

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Traded my Harley at the dealership with these mods and more. They cut me a check and it paid for my Super Tenere outright. If the dealer won’t work on your bike you are at the wrong dealership. They make money fixing bikes and usually won’t turn away Business.

If some one is willing and brave enough to try these mods then I applaud their efforts. I did it with my Harley and I am now letting others light my path so things go smoothly.
 

lukasteam

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Guys , I didn't have enough riding time to check everything , so not sure about fuel economy if it will go down it shouldn't be much at all , probably no more than 1 mpg .
I have absolutely no back popping at any rpm's which is the proof that ECU compensates for it and does it's job .
I'm still running the stock can , I thought about gutting the stocker , but would like to go aftermarket .
I would look at the de-cat and aftermarket can just the way I would look at let's say full Arrow system from many aspects . Actually I think the stock de-cat headers are a little better since it has a little gas expansion chamber now where cat used to be to keep gas moving even better . If full Arrow with the right map gives you torque and hp gains , de-catted headers and aftermarket can should do too .
On a dealer subject , I'm sure they not turning down Arrow guys for service , why would they turn down the stock de-cat . I don't think they x-ray your headers to check if the cat is still in there .
Stock headers also accept ACD skid plate with no bending or extra washers like you have to do with Arrows . Plus a money savings ... win , win in my book .
Thank you again guys for all the compliments and likes , it makes it all worth while . Love helping other people , that's what life is all about .
 

twinrider

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I found on my last S10 that the gains lay in the Arrow headers. My bike ran better with the stock muffler/Arrow combo than it did with the Akra/Arrow combo, better torque at lower RPMs. I did have an ECU flash and a PCV mapped for this set up.
 
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