Hey, Guys and Gals. I'm new here and thankfully, somebody's taken me by the hand to get me to the right spot for my post.
Thanks for the bump start. It's even better'n an "E" button for obtaining answers...I hope.

I am curious as to who's experimented with aftermarket exhausts on the new KlX 250. I've read several opinions about factory vs. aftermarket headers, muffler only, etc., but has anyone actually done any comparisons?

I spoke with Jerry Leighton at Four Stroke Works and he'd love to have someone bring him a bike for proper fitment of his pipes on the KLX 250S.

If you live near Hesperia California, give him a call at 760 948-0325 and tell either Jerry or Valerie that Bill from Oklahoma said he needed a doner bike to fit a pipe to.

Let us know if you're able to help. He does a lot more than pipes too. Jerry worked with Larry Roesler back when he had Stroker. He's the man for KLX mods.

I am particularly interested in knowing how much improvement anyone has seen with various header or header and muffler swaps.

Let us know your experiences and if you're able, give Jerry a call.

Shadetree

 

[sm=badidea.gif] uh o.... here we go again....

the search button is your friend....do a search for exhausts, there is a world of exhaust discussions

 

Shadetree,

Oh there are some opinions about which exhaust is best for the KLX, quite frankly it is not based on any data obtained via dyno testing.

Without going into any detail whatsoever, let me just say that there are many choices, all of which better than the stock muffler, for you to base your decision on.

If you do any real testing, let us know what you find.

From our discussions we all feel that any exhaust is better than the one provided by Kawsasaki for the KLX250S. I personally have noted that the amount of air flow between the stock and the aftermarket exhaust on my bike is very, very noticable when standing behind the bike. Is that good or bad? I don't own a dyno to know for sure, but it sure does run a whole lot better! Of course, you also need to provide jetting to make the mixture right.

Good luck and let us know what Jerry sez.

 

Thanks, Marty.

I have already done the emissions mods, removed the screen and lid from my airbox(still need a hi-flow filter), installed a Mikuni TM33 8012 flatslide carb(still fussing with jetting a bit). I'm leaving gearing alone for now for the sake of accuracy on my calibrated butt dyno. So far, it's another bike from the 18 horse PW (Could mean either), motored bike I rode home a couple of months ago.
The pipe is next. I've looked at Staintune, Big Gun, Muzzy, FMF and a few others, but even the folks that sell most of these pipes don't know much about them. I was impressed with Jerry at FSW most of all, but he actually does the building. He should know more than a guy with a catalog and a phone.

I don't want to be re-packing it every month nor do I wish to listen to the noise my neighbors make when I'm making too much noise.
Need more power, of course, but I'm not ready to cut the bore or swap to a 300. I'm not racing, just wanting to let the muscles already there out of the bottle.

So. Opinions are helpful, but the more specific, the better.

Shadetree(Bill)

 

Shadetree,

You might want to take a look at HMF Engineering and their website.

They are about the only ones that have performed any dyno testing that I have seen published.

Here is the link to their article on the KLX250S development work they performed.

There is also a "Flange Mod" that some have done to get rid of a big old "gob" of welding crud on the stock exhaust header.

Let me know what you think.

 

Hi Shadetree (Bill)!

Welcome to the Mecca of all that is KLX250S!

Marty did a good job in summarizing the exhaust "can-of-worms", and like EMS suggested ... the Search button will get you more information than you probably want. And it seems that more vendors are getting on the KLX250S exhaust bandwagon as we speak!

I'm interested to hear about your Mikuni jetting experiences. I just bought a Mikuni pumper for a Suzuki DR350 through eBay, so I'll be looking for mounting / jetting information. (When I receive the carb, I'll probably start a new thread on the topic.)

Mike

 

Zhady-

I have the FSW muff and header. The muff is so close to the bike, and so long that it started to melt the fender a little. No prob for Jerry, I'm sending him some pics and he is going to revise for me. The performance and sound improvements are awsome, even my riding buds noticed the performance improvements. I think he's a good guy too.

 

Mike,

I just got an e-mail telling me my "modified for the KLX250S" Mikuni TM33 is on it's way to me.

I'm keeping track of when the Big Brown Truck turns into my subdivision.

The mods that were done by Bill Blue make it fit right on to the KLX250S. No adaptors required. He builds up the adaptors to 34 mm in diameter and also offsets them.

If you run into trouble, here his email b_jblue@sbcglobal.net

I hope to have mine this weekend, all ready to just bolt on and wheelie!

 

I removed my stock header to perform the flange-o-matic mod, only to discover that there wasn't much to remove. Maybe this varies between bikes? I ended up using a dremel grinder and some time to take off a little bit, but honestly, there wasn't much there that exceeded the inside pipe diameter of the tube itself.

On another note (couldn't resist the intro), I see many comments about how "sweet the sound" is of aftermarket exhaust, or joy of simply how loud it is. I have to say, while I don't want my bike to sound like a moped, I really don't want it to be loud. When riding off road, noise only pollutes the area. I know many don't care, but I personally do. Also, its important to remember that one of the main reasons that areas get shut down to offroad vehicles is noise. That said, I keep hoping to find ways to get some good flow improvements out of my not very loud stock exhaust - drilling holes here, grinding welds there, etc. I suspect I will not be able to come close to the gains of an aftermarket setup, but compared to my friends klx running a Muzzy w/quiet core, my bike is much quieter. I'm stuck between wanting the power gains, and not wanting to wake up the neighborhood when I leave for work.

 

I'll 2nd Jerry! He is the man! That guy has more KLX knowledge in his pinky finger than most folks will ever aquire in their lifetime. He's also a great guy and when I was speaking to him about my carburetor even before I was planning on buying one, he was genuinely interested in helping me out and that didn't appear to be tied to any hope that I might buy something from him. There was no pressure to buy anything and he was even giving me a load of tips and tricks to get my existing CVK carb working better on the KLX to get the most out of what I already had without having to spend a dime with him. That's actually where I got the idea for the separate crankcase vent filter - Jerry recommended it. So he's not out there trying to separate you from your money with no value exchange - he seems genuinely interested in making your bike run better. Ultimately, that's where I ended up buying my Keihin FCR pumper carb and most folks here know that has turned out quite well.