LC4 640 Exhaust woes

I need some suggestions guys. I have a 02' 640 and need an exhaust system. I spent the dough on a full Big Gun :) system and had it on my bike for two years. It fit horribly when it was new, never sealed right, rattled, and rested against my cylinder head and melted a hugh divot in it. I was in Mexico on a 1200 mi trip to Copper Canyon, when the headers moved forward and burned a hole in the radiator. :)

Needless to say, I removed the system and sent it to the dump after the sledge hammer was done with it. Very few mfg's make anything for this bike, esp exhaust. Any suggestions welcome.

Thanks in advance.

I installed the Akrapovic Ti system yesterday. It fit perfectly. I mean PERFECT! It is expensive, but well worth it in my opinion. Save your cash until you can get the complete system with the quiet insert. You will not regret it. This pipe, in combination with my FCR 41, has created a tremendous increase in power over stock. Well worth the investment.


So you have an Akra with a "quiet" insert? How quiet is it? Have you had it sound tested? I've always had a yearning for an Akra but I really have to have a quiet bike. Too many riding areas around me have been closed due to noise. There are still some little known smaller areas but they are close to residences, so I have to have quiet. Is there a KTM part number for the quiet Akra?


Staintune make a nice stainless steel unit and you can look them up ar If this fails KTM make a EXC type muffler that replaces the heavier one.

This is the first I've ever heard of anything like that happening. Most 640 owners who add the BG say it takes some tinkering, but they get it to fit and like it. AAMOF, a guy I ride with has the BG on his '03 Adventure. Fits great.

Personally I still have the OE anchor on my Adventure. Just added some disks to trim out the jetting changes.

The Akro just seems like a waste of $$$ unless you are a hard core racer. If your running a 640, the odds are you aren't.

I don't know if you're familiar with, but if take a look over there, you'll be able to dig up all the exhaust info you'll ever need.

You can use the KTM Competition Silencer 583.05.081.300. They seem to be good but then you'll need the stock head pipe.

I have a full BG system on my 99 ADV and it fits like crap too. I have tons on silicone on the heads just to keep it from leaking....

If I could find a stock system I would trade in a minute.

You Have To Use The Proper Sealent On Any Pipe Let Alone The Biggun . On Mine I Use Sealer From Midas Muffler , Small Tube ,works Great. Silicone Turns To Dust In Minutes . Fitting The Biggun Is A Challenge , You Must Take Your Time And Check Fit Constantly , Mine Does Not Leak , Bigguns Quality Control Is Spotty , They Do Have An Excellent Return Policy , I Know Ive Used It Twice. Make Sure Your Header Springs Are Not Weak Also.on Mine I Position Both Header Pipes First Then Adjust From There Back , Shimming As Nec To Keep Pipe Of The Frame . Its Not That Hard , The System Works Well At Half The Price Of The Akra.

Thanks for the input guys, I'm looking into your suggestions.

I tried everything imaginable with that damn pipe to get it to fit/seal. I settled finally on that orange colored high temp sealant that lasted a fair amount of time. My riding buddy has the same bike, pipe, and problems......maybe we just got a couple P.O.S. pipes out of a bad batch. I'll tell you what though, it was worth $600.00 to beat the crap out of that thing with a mallet when I took it off :) . I know violence is the tool of the ignorant, but sometimes in the privacy of your own garage you gotta do what ya gotta do.

Everybody has problems with something. Heard horror stories about Yosh pipes, but have run them on several bike with no problem.

One more question, running that factory KTM slip on muffler with the stock head pipes, does it come with a new mid-pipe? I seem to remember the stocker was one piece from the muffler to the headers. Could be wrong, it's been three years and I am getting C.R.S.

there will still be the strangalizer aka premuffler to deal with you can get a midpipe from sommer ktm among others , when i added the ktm sxc slip on , there was only a slight power increase , get a full system for max juice. :)

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