SXC Exhaust on 03 LC4 Adventurer

[Arch]

Originally Posted by markjenn

P.S. In looking back at the pictures posted earlier, my SXC Comp muffler looks like the one pictured, but I note that the rear hanger looks like the SuperMoto one with a large open hole that looks like it should take some kind of bushing, whereas the SXC Comp muffler seems to have the bushing. I had no issue bolting the "big hole" up to the hangar on the bike, but it would work better if I had the bushing since the only thing going through the huge hole is a small 6mm bolt. Anybody know what bushing I need? I'll make one up if they're not readily available.

It's sized to use the stock bushing...

[Katoum]

Originally Posted by Arch

It's sized to use the stock bushing...

Arch I believe that the muffler you have posted uses a grommet that attaches to the muffler hole and then there are two machined aluminum pieces, one that serves as a spacer and goes thru the grommet and the other one is the matching washer for the other side, these are used on the EXC models and you can find the part on KTM Talk 54605069000 and 54605068000 .

[markjenn]

My SXC Comp muffler just has the big open hole in the hangar without bushings, spacers, etc. Thanks for the numbers, I'll see if I can source the proper parts.

- Mark

[Arch]

Originally Posted by Katoum

Arch I believe that the muffler you have posted uses a grommet that attaches to the muffler hole and then there are two machined aluminum pieces, one that serves as a spacer and goes thru the grommet and the other one is the matching washer for the other side...

Yep, I was just showing the bushing. Here's the full setup...



Again, bolts right up using the stock stuff. At least on my '01.

[Esteban]

Guys,

I thought I'd throw my 2 cents in here. This is what a dynometer, exhuast gas analyzer and my 99 640 LC4e taught me.

The bike started out with 42 rear wheel HP - anemic, and would not breath well at high speed.

Main impediment to power is the stock exhaust. Does not matter how many discs you put in, the overall design of the Supertrapp can is restrictive. The restriction lies upstream from the discs.

I live in Denver at 5500 feet and ride up to 13,000 +

I swapped to the 41 mm FCR carb and run a #138 main. This jetting set-up gave the correct fuel:air ratio of 13:1 I am running a #40 low speed jet, and the needle clip in in the third groove from top (there are 7 grooves total). I might lean the needle one more soon. Sudco supplied the carb "prejetted" for my altitude with a #170 main - Ha, that was a joke !

Also, snorkel has been removed and air box top inlet hole doubled in size. I can still ride in water up to the exhaust outlet (Have you ever heard an LC4 exhaust underwater ? sounds like a motorboat.) and it will not die like it would with a screened side cover.

My stock 1999 version (external disc) Supertrap is heavy, but can be made to flow better the the stock KTM SXC Competition pipe with internal surgery. I proved this to myself on the dyno. I think the later SuperTrapp IDS is basically the same internally as mine and can also be made to flow much better. There are about 5 HP lurking here and the noise does not go up much if at all. The spark arrestor becomes .... ?

Since I got a good deal on and SXC Competition can I put it on and my HP dropped noticealbly. Hmmmmm.... ??? !!!

I drilled out the stainless rivets on the rear cap and saw why - the tubes bringing the ex gas from the engine went past the tube exiting the cap. This forced all exhaust gas to flow backwards to exit the end cap. I cut some of the internal end cap pipe off giving a much straighter shot for the EX gas to exit. Not a perfectly straight shot as the gas still has to do a little zig (as in zag) but it no longer has to flow backwards. It also seems like it would be very easy to run some stainless screen on the internal pipe on the interior of the end cap to create a spark arrestor.

The hardest part was finding the correct size stainless steel rivets to reassemble the unit. These had to be special ordered form an industrial parts supply place. Aluminium rivets will wear and break from what I heard. I also think think it would be easy to weld some nuts in place on the interior of the end cap so that it could be screwed instead of riveted.

By the way my current modded SXC cannister tested at 92 dB at Copper Mtn DS oraganized ride. They measured it 20" from the exit hole at idle and at about 3000 rpm. (Their system not mine.) It tested much quieter than most other bikes going on the ride.

My bike is now running at 51 rear wheel HP as compared to the 42 RWHP I started with. It will easily pull over 100 mph indicated with a 16:42 final drive and will peg the speedo with the 17:42 final drive. My mileage is in the low 40s , but I am hoping to get it up to 45 mpg by leaning the slide needle a little more. We'll see since I sometimes get lazy and let it go for long periods since it runs real well as is. You can waste a lot of great riding time trying to achieve the "perfect" jetting. I think it is within 90% of perfect at the moment.

Hope some of this info helps.

Steve

[Nopork]

Originally Posted by Esteban

Guys,


Main impediment to power is the stock exhaust. Does not matter how many discs you put in, the overall design of the Supertrapp can is restrictive. The restriction lies upstream from the discs.




My stock 1999 version (external disc) Supertrap is heavy, but can be made to flow better the the stock KTM SXC Competition pipe with internal surgery. I proved this to myself on the dyno. I think the later SuperTrapp IDS is basically the same internally as mine and can also be made to flow much better. There are about 5 HP lurking here and the noise does not go up much if at all. Hope some of this info helps.

Steve

What modification did you do to the stock Trapp? Drill out the center pipe at the rear and/or?

[Esteban]

Basically I created a 1 " hole all the way from IN to OUT side of the muffler. This required the use of drills, bars, hammers, chisels, hemostats, bailing wire, vice grips, flashlight etc. Took about 4 hours of orthoscopic surgery.

The way the Supertrapp is made it readily comes apart inside and then you are left with shaking sheet metal parts internally that are difficult to remove.
With patience and care they can be removed and the exterior of the pipe remains unchanged. The pipe will still be quiet, but once again t he sp[ark arrestor remains a question. I think that the discs count as a spark arrestor though in the eyes of the USFS.

STeve

[meat popsicle]

Originally Posted by Esteban

Basically I created a 1 " hole all the way from IN to OUT side of the muffler. This required the use of drills, bars, hammers, chisels, hemostats, bailing wire, vice grips, flashlight etc. Took about 4 hours of orthoscopic surgery.

The way the Supertrapp is made it readily comes apart inside and then you are left with shaking sheet metal parts internally that are difficult to remove.
With patience and care they can be removed and the exterior of the pipe remains unchanged. The pipe will still be quiet, but once again t he sp[ark arrestor remains a question. I think that the discs count as a spark arrestor though in the eyes of the USFS.

STeve

Hmmm, if you can install the discs then you can install the spark cap, right? The cap is the arrestor; without it you are not Smokey's buddy.

I wonder if just drilling around the internal opening or hole punchin out the internal hole and pullin the whole pipe, as others here do, is good enough? That is without gutting the whole thing.

Here is Ktmnate's webpage with his stock exhaust mod pics:
http://www.geocities.com/nsaca/KTMExhaust.html

[Chrisbarnes1]

Having run a slightly modified stock exhaust on my 2006 adventure I came across a secondhand John Deacon exhaust in polished stainless and took a punt. Its really designed for the pre 2003 and earlier adventures with a different subframe etc--but I made it fit. I had to dress out the joint end a bit to get it to fit, and add an extender bracket off the subframe for the front mount as I used the existing two front isolator mounts. Its smaller, much lighter, and sounds pretty good with the end gauze in. I have the KTM recommended Akrapovic main jet upgrade should I need it --but we'll see--they are both straight through. Here's some pics.

[Gale B.T.]

Wow Chris, beautiful job fitting that can, I would love to see a short video with the new sound, I can only imagine how nice it will be.

Congrats , I know you will enjoy
gale