Funilly enough... yes ! Waxed once, washed, vacuumed & interior detail twice. Am I a clean-freak or what ! And then there's the 3D Printer.....

 

Ever see the Honda commercial where the new owner dives across the hood when a flock of birds flies over ?

 

Nope, but I would do the same thing !

 

has anyone tried this on the duke 390 ?

https://www.youtube.com/watch?v=TAk1ABgcO04&app=desktop

How does the hole cut in this video match up with the structure in the 390 mufflers that have been dissected?

It actually sounds decent to me and with Akra map, maybe there won't be too many negatives?

 

In creating the 390's underbody exhaust, KTM evidently did a thorough job of research and testing, ending up with a system that contributes in a major way to the engine's class-leading power output. The principal feature of this exhaust is a carefully-tuned header and exhaust length such that the resonant frequency of the exhaust pulse waves helps scavenge the exhaust gasses, leading to better cylinder filling/more power. KTM engineers did their homework and produced a very successful component in terms of power extraction from the motor. Unfortunately, very likely for reasons of cost, it was decided to build the exhaust cannister out of mild steel, resulting in a rather heavy lump which could have been significantly lighter if built with other materials.

The video posted by Sinha shows a Duke owner, in a quest for "better sound/more noise" amateurishly cutting a hole in the the exhaust cannister. The probable result of this uninformed intervention is to disrupt the resonant frequency of the tuned exhaust system. Undoubtedly, if this bike were tested on a dyno, first measuring power with the intact OEM exhaust, then comparing this with the altered exhaust's performance, the latter would show a power loss.

Exhaust design is a complex engineering project that draws on several sub-disciplines of physics. It is not for amateurs, or even for aftermarket companies without the necessary design and testing resources. Just to illustrate the difficulties of exhaust design, read the thread below from the RC forum, describing Formula390's efforts to build a lighter, better sounding, more powerful underbody exhaust for the 390 engine:

Exhaust development work

 

Understood Diploman, it's why I was asking if a hole was placed in the spot as shown in the video, what do we think would be the impact, after comparing to the dissection views previously shown. I need to take a closer look at the opened exhaust, it's possible a hole here actually bypasses the full reroute through the catalytic, but I can't be sure yet due to limited time to carefully review the pics.

 

Hmm
https://youtu.be/Qy-7OrV5e1k

 

That ground-breaking experiment & video was made by ex-forum member Rick D. He sold his 390 shortly after for a Yamaha MT-07 & we haven't heard much from him since.

 

@Diploman; I followed your recommendation and spent the last 1-2 hrs studying the RC 390 "Exhaust development work" thread. (We can now we're retired). That is some amazing R&D and absolutely nails what you have been telling everyone. "The stock (2013-16) exhaust is a masterful work of very complex engineering". My interest isn't sound or power it is weight. I would like to get rid of the cat which is heavy and not required by legislation down here. Having read Formula 390's comments on his decatting experience I accept that's in the too hard basket for me. Going for a lighter product using the existing geometry just increases noise with zero performance gain and more likely performance decrease. What is really interesting is that the 2017 has this additional exhaust, clearly to meet Euro legislation, that can only be detrimental to performance and detracts from the original design genius..

 

Peter, I'm glad you had a chance to read the long thread by Formula390 documenting his prolonged but ultimately unsuccessful efforts to create an alternative to the OEM underbody exhaust. Knowledgeable people who have studied the stock exhaust are genuinely impressed by its engineering and effectiveness. This is a very cleverly designed piece that extracts excellent power from the engine, emits a civil exhaust note and meets developed country pollution standards, all in a compact, mass-centralized unit that is nearly invulnerable to crash damage and does not interfere with luggage.

Sadly, this highly-developed product of KTM's engineering team is underappreciated by a sector of 390 owners: it is most often maligned for being too quiet and vilified for not producing a more raucous exhaust note. (NB. I just learned from watching a YouTube evaluation of the new 2017 Duke by an Indian tester that the new exhaust reportedly was necessary because the 2013-16 exhaust could not meet Euro 4 NOISE standards - the outgoing stock exhaust was sufficient to meet the emissions standards but was TOO LOUD!!) Those who criticised the Gen 1 exhaust's moderate tone will find even more fodder for frustration with the new 2017 unit! Still, many 390 owners have been eager to spend large amounts of cash on aftermarket cannister exhausts that are only marginally lighter, produce little if any gains in power/torque, require an expensive fuel controller to protect the engine, and are very vulnerable to crash damage. The chief "benefit" of these exhausts seems to be that they are less successful than the stocker at dampening exhaust noise.

To my mind, really the only sin of the Gen 1 stock exhaust is that it is rather heavy - about 14 lbs (6.4 kilos). Likely for reasons of production costs, the whole unit is fabricated from mild steel, rather than alloy, resulting in a somewhat hefty lump - but still much lighter than the 2017 stock exhaust.

To date, the only worthwhile potential candidate to replace the Gen 1 stock exhaust - IMO - has been the Werkes Competition unit, a small underbody canister that fits in the OEM location. The Werkes is very simple and lightweight, reportedly saving about 10 pounds over the stocker. Reports about its effect on power are unclear, but certainly it will require a fuel controller. Until recently the Werkes was considered unacceptable because, as delivered, the unit has no sound packing and is extremely loud. However, some recent experiments with disassembling and packing the Werkes reportedly have been quite successful. Our colleague CDN Duke is presently testing a packed Werkes on his bike and appears to be pleased with early results. We will have to see how durable the packing may be. So if you are interested in saving weight over the stock Gen 1 exhaust, the Werkes, IMO, is your best candidate. Stay tuned. But you will have to be prepared to fit a controller.

 

To date, the only worthwhile potential candidate to replace the Gen 1 stock exhaust - IMO - has been the Werkes Competition unit, a small underbody canister that fits in the OEM location. The Werkes is very simple and lightweight, reportedly saving about 10 pounds over the stocker. Reports about its effect on power are unclear, but certainly it will require a fuel controller. Until recently the Werkes was considered unacceptable because, as delivered, the unit has no sound packing and is extremely loud. However, some recent experiments with disassembling and packing the Werkes reportedly have been quite successful. Our colleague CDN Duke is presently testing a packed Werkes on his bike and appears to be pleased with early results. We will have to see how durable the packing may be. So if you are interested in saving weight over the stock Gen 1 exhaust, the Werkes, IMO, is your best candidate. Stay tuned. But you will have to be prepared to fit a controller.

Packing options are being discussed here: Packing Werkes Exhaust + Dyno!

Note that the Werkes pipe does come with packing from the factory, but the original packing doesn't tend to last long. Mine has been repacked by Competition Werkes with a ceramic material rated at 2300 degrees. Not sure if this is upgraded from when they first released the pipe or not. However, it is quite common for these to blow out the original packing in relatively short order. Competition Werkes will repack at no charge, you just need to pay for shipping. When packed, I think the pipe sounds great but it is admittedly on the louder side.

 

I just purchased a Competition Werkes exhaust. Unfortunately, I will have to wait to install it until after I purchase a PCV...