Decatting the Cat - Budget Decat Pipe KTM Duke 390 125 200 250

[@andrewwiltse8882]

Another great way to make things work with what have on hand. I’m 57 and we lived like this my whole young life and I still do. Thanks David

[@MotoMirius]

Thanks Andrew. Funny we just had this conversation at home. Younger people here have not so much idea to do this - it's all throw away and replace.

[@zacharynapoleon4428]

You can actually make pretty decent power while using a de-catted cat. I used a drill press to put a bunch of holes through the cat material then pushed out the chunks (hopefully that doesn't shorten my life by too many years). On the dyno my RC 390 made 47 hp and 30 ft-lb of torque to the wheel using the stock exhaust system (de-catted and with the baffle drilled out), a Powertronic ECU, K&N air filter, open airbox mod and gray area KTM oversized fuel injector. I rode the 390 like that for a little over a year and roughly 10,000km and since then I've installed a tyga header and MPG exhaust. My butt dyno says it's making more power now but I still need to bring it to the actual dyno and probably adjust my map.

[@MotoMirius]

Yes, of course you are going to gain power, though probably not as much as through a better flowing pipe - my objections to this are potential health risks, not to decatting - which is why I run a decat. One of these days I will need to do something about the header - I guess with the revised BS6 header there is now no chance Tyga will make one for the gen 2.

[@kevinpinheiro2485]

Hey, had a question. If I make a decat pipe… do I need a re flash for the ecu ?

[@pokojoe9741]

Thanks for the great videos. When you cut this cat tube to take out the cat, how do you make up for the difference in length to the pre silencer? Thanks

[@MotoMirius]

The difference in length is the width of the saw blade. When welding the outer tube back together simply leave the a gap the same as the width of the saw blade - the weld will bridge this gap.

[@shenwei8305]

Will there be a sound video on the Decanting the Cat installation next?

[@MotoMirius]

It won't be next, but there will be some videos coming on that, but first I really need to be out of lockdown properly again otherwise it annoys the neighbours to be revving the bike repeatedly.

[@springy-2112]

Hey David . I think you need some quick release clamps for the exhaust parts ! That cat has been on and off more times than the under garments of a lady of ill repute ! (me trying to be Pc ) . Peace and love brother. Good show. 👍🏻☮❤

[@MotoMirius]

Ha! Oh yes, I've lost count of how many times this has been off now! Thanks Springy

[@Tryneditjfan]

Hey David, do you know if i destroy the Garantee on a ktm duke 125 2021 by putting out the DB killer on the bike?

[@MotoMirius]

If you modify your bike then your warranty is no longer valid (unless you are fitting KTM supplied products). The only way to protect your warranty for this modification is to fit a Coober piggyback as they will take over the KTM warranty for you.

[@ricardopinto1765]

Hello Marius... Just a question!? Benefits on doing the decat and do I need to flash ECU after doing it!? Thanks once again😅❤

[@MotoMirius]

Benefit mostly increased sound level with the bike still looking mostly stock but also some potential for more power. If this is the only change you've made then most people are fine with the stock ECU, but if you have made other changes then best to look at a piggyback ECU - FuelX Lite (not Pro) if you want plug and play.

[@ricardopinto1765]

@@MotoMirius living in Europe more specific in Portugal I was looking for the rapid bike either easy or Evo like the one you install in your duke easier for order (EU regulations) ... Thanks 💥💯😊

[@MotoMirius]

Thanks. Easy is a bit outdated now but Dimsport have not yet launched it's replacement yet, which is why I mentioned the FuelX - but the Evo is better@@ricardopinto1765

[@cavitecheckpoint]

Another great specially for those who like stock parts, you already have the, stock exaust mod, stock tail tidy mod, please make the stock side mirror shortening mod, i think the stock side mirror look good and iconic. Great video always ride safe😁

[@MotoMirius]

There are always those who love the stock look, and to be fair the designers spend a lot of time getting it just right. Mirrors are on my list, I just need to figure out exactly what I want to do with them!

[@fredstah714]

I actually I just take the exhaust and leave the cat. Sounds amazing.

[@MotoMirius]

The flexibility this system gives to achieve the sound you want is what I love about it.

[@stevensutcliffe2033]

Do you need a power commander or remap for this mod

[@MotoMirius]

@@stevensutcliffe2033 It depends. If you've made no other changes, many people will get away with it. But to be safe, a piggyback, even an entry level one, is a good idea

[@newhorizon4879]

Hello after I’m putting it back together , do I need to refresh ecu or I just take the cat out and it’s work fine ? Don’t need to do anything ?

[@MotoMirius]

Depends if you have done anything else. If this is your only change you may be OK with just riding, but if you have made any other changes then you should add a piggyback ECU, at least a FuelX Lite (not Pro) - probably a good idea to add this anyway to be safe.

[@newhorizon4879]

@@MotoMirius thank you for your answer I’m just really thinking to Hammer it out , and put it back , but I’m concerned about error light like check engine etc , I have an Akropovic exhaust , but only the last part I still have the cat and the pre silencer , and also I’m thinking to just buy a pipe cuz if the air flow not perfect like it’s mentioned in the video , without drilling it , idk better just get a pipe

[@kevinpinheiro2485]

Nice one. I removed my dB killer on stock exhaust. Will doing same for the cat make the bike more better ...like exhaust the gasses out more efficient? More sound too I guess 😅.

[@MotoMirius]

Removing the cat will make your bike much louder. DB killer makes the bike a little louder, removing the cat makes it a lot louder. I tend to run no cat and with DB killer. Yes, it will make of course make more power because the cat blocks the exhaust - but only if you have a fuel map which can take advantage of it.

[@kevinpinheiro2485]

@@MotoMirius got it. Btw had to ask. I've seen these after market muffler with a dB killer that we can remove with a bolt. So I was thinking is it possible with the stock. I still have my dB killer. Thought to get a cup like welded around the dB killer. The muffler already had a hole so I thought to use that to screw the dB killer.

[@MotoMirius]

@@kevinpinheiro2485 I have a video on putting the db killer back into the stock muffler. You could improve it.

[@kevinpinheiro2485]

@@MotoMiriusThanks. seen that. I am looking for a good welder. I have a friend who is good but due to covid we're on lockdown. What about these dB killers that we get that slides in between the muffler and underbelly? It's same as the the cat converter shape ( what was inside). My only concern is if it puts too much restriction.we have traffic rules here that don't allow to modify the exhaust system. But usually the bikes way too quiet. Here in India, most of the pedestrians don't use zebra crossing and just run randomly across the street. So I've had incidents where they don't even hear the bike. Nothing happened but I felt this was one of those situation where loud bikes save lives. After removing the dB killer. I found out that people somewhat knew that there was a bike coming. But this is kinda not street legal. So I thought like put a removable dB killer that when I wanted I could remove it.

[@MotoMirius]

@@kevinpinheiro2485 You can put a db killer anywhere in the system - it's just a baffle. I chose the stock location because it's where the police etc expect to see one. If one isn't there then you are just creating something for them to fine you for because you'd have to prove that you had one and it was just as quiet as it was from the factory - it's why I like to have exhausts which look stock but aren't for street riding.

[@mafiaboy4925]

After removing the cat from my pipe I can tell you that my overall fuel economy has gone by like 25 km/l litre to 20 km/ litre whis ( 58-60mpg to 47mpg) can you explain what is the issue here

[@MotoMirius]

There are two common issues here and often it can be a mix of both. First is more use of throttle because you can hear the bike more. Second is whether your ECU is adjusting (depends what if anything you are running with the stock ECU) - it can take a short while for the ECU to adjust fuel levels

[@eliasbragvin8288]

Hey, my ktm duke 125 2017 almost and sometimes dies when i pull The clutch in at low speed. This problem startet when i installed a leovince decat. What should i do? Just adjust the idle on it or?

[@MotoMirius]

Sounds more like clutch drag. When problems slowly arrive it’s easy to link it to the last thing you did but that isn’t always the case.

[@Funny_as_Duck]

I was wondering if it’s normal if all I did was put a wide open exhaust for it to have lost so much power? The stock exhaust seemed like it had way more torque in 1st and 2nd where I could do a wheelie just from the throttle. But now it’s lost the power

[@MotoMirius]

Bear in mind that the stock fuel map is designed for the stock exhaust setup. This is why I will typically talk about these mods for increasing sound levels - if you want to take advantage of the potential increase in power then you need to start thinking about making changes to the fuel and ignition mapping. If you have the right map then you shouldn't lose any torque.

[@impreza99rs]

Awesome video!!!

[@MotoMirius]

Glad you enjoyed it

[@knov1153]

Could you tell me if it makes sense to replace the pipe itself without the collector and will everything be ok without the map?

[@MotoMirius]

My rule of thumb is that one change to the exhaust system is generally OK for most people. Removing the cat pushes that limit so you do so at your own risk. I would generally recommend at least one of the simple piggybacks, but it really depends on what you intend for the bike.

[@knov1153]

@@MotoMirius My duke 390 has basically been a stunt conversion for a while now, although I want to keep its power. So in your opinion, the replacement of the pipe itself will be ok?

[@MotoMirius]

@@knov1153 Stunt conversion makes no difference to this. My recommendation above is the same - there are no guarantees unless you put the bike on a dyno and test it for you location and setup. My recommendation if unsure is always to get at least a basic piggyback.

[@XtianHC]

WITH THAT MODIFICATION, CAN I HELP THE ENGINE COOL BETTER?

[@MotoMirius]

In theory it will run a little cooler, but engines are designed to run hot so the effect will be very small. If the engine is getting too hot then you need to improve the cooling system and airflow to the engine.

[@tomkitchen2764]

Way too clever for this kid to tackle.

[@MotoMirius]

To be fair, it's much easier just to buy a pipe - so long as you have the budget for it!

[@TheJWC56RSA]

I was waiting for this... how loud will the 390 now be? I intend to do the same... I have the RB EVO piggy back already set on 3 (for fuel) because the 390 runs so lean. By decatting it may even be leaner?? Thanks en regards David!

[@MotoMirius]

If you've got your EVO set to three then you need a refund because only the Easy can be set to three ;) Decat will indeed make it leaner - you can see in the video just how restrictive the cat is.

[@TheJWC56RSA]

@@MotoMirius Sorry - Easy!! :-)

[@alvaroalicata8239]

what did you use to weld? wich filler rod?

[@MotoMirius]

MIG, I didn't bother to change to stainless wire.

[@alvaroalicata8239]

@@MotoMirius fyi I just checked the material with a Hitachi xrf and says SS303

[@MotoMirius]

@@alvaroalicata8239 Thanks, that's useful. The whole system is stainless so that isn't a surprise.

[@giuseppecrispo703]

😎👍

[@MotoMirius]

Thanks. Skäl David

[@marks2961]

He makes good videos - but his comments on the cat retaining the pollutants is nonsense. A catalytic converter just provides a chamber with a media (the catalyst) and contact time that allows volatiles that get past the combustion chamber to burn off. It does not retain those volatiles - the bike would have to inflate then (lol). By definition, a catalyst is something that facilitates a reaction (in this case more complete combustion). The metals within the cat may not be great to ingest - though they are pretty inert generally, but the cat itself is no more toxic from use than the rest of your exhaust. And, the fumes you would be exposed to welding are clearly more dangerous to your health. Any - he does great bike stuff - but maybe should avoid the health advisories...

[@MotoMirius]

Feel free to breathe the particles in. I'm not going to advise it in a video.

[@tinks43]

Bog standard… Honest 🤣

[@MotoMirius]

I don't know what you mean officer!

[@heartwarmcentral]

I have an ktm duke 2021, with an akrapovic slip on, and the rest of the system is stock. Is it the same process and if not could you explain?

[@MotoMirius]

If you have the BS6 bike with the exhaust under the engine then no, you need a 2021 decat pipe because the cats are inside the header pipe.

[@heartwarmcentral]

@@MotoMirius 125cc btw

[@MotoMirius]

@@heartwarmcentral makes no difference - the BS6 (2020 in India, 2021 rest of the world) will have a difference cat replacement pipe but I'm not sure if anyone is making them for the 125 yet. This is a problem with buying a new model bike - it takes the aftermarket manufacturers a while to build, test and develop new products to fit, which is one of the reasons I tend to buy slightly older bikes where second hard parts and second hand aftermarkets parts are available.

[@heartwarmcentral]

@@MotoMirius ye well kind of regretted it, but also not. Since I will be getting my license in may

[@heartwarmcentral]

@@MotoMirius and by then they may have figured out a way to get the full exhausts and stuff