Need the sage advice of this forum. Have my new project at the ranch, finally, an `06 KLX. Kustom Kraft 331cc cylinder kit is on a UPS truck somewhere. Gonna run the stock cams and carb at first, enriched of course.

Now I'm thinking about exhaust systems, but require not irritatingly loud and if I could lose some pounds that'd be great.

Bought a KLX300 header pipe off Craigslist cheap, and have my eyeballs on a KLX300 muffler, also cheap. They would increase capacity without being irritatingly loud. Loud exhausts are SO bad for our sport and I'm beyond needing a 'psychological' (read: perception of power through noise) boost. Oh I know, the loud pipes do add power, but at a cost of irritating the world and me, it's just not worth it to me, so unless you all know of quieter alternatives, I'll do the KLX300 thing.

Shadetree had a Muzzy once that was SO irritatingly loud I couldn't stand to ride behind him, and the closest neighbors half a mile away could hear him. He now has the FMF Q4 with their little puffed-chamber header and speaks well of this setup. It did not seem so loud, though when I heard it I was set to take off on a road ride and I had ear plugs in. Are there truly quiet(er) aftermarket alternatives?

About weight, has anyone weighed the KLX250S and KLX300 mufflers and a quieter aftermarket alternative? A substantial weight loss up high on the bike I admit is my biggest draw to aftermarket. If not substantial, I'll stick with the durable (and quiet) steel cans.

Addition: If you don't know where I'm coming from, read this:
http://www.sharetrails.org/magazine/article.php?id=45

 

Hi I just put the FMF Q4 slip-on on my 07 250s last sat. I weighed them both on my shipping scale. The stocker off of the 250s weighed 8lbs even, the new FMF Q4 weighed 5lb 7oz.
I didn't want a really loud muffler, and from what I read on here the Q4 sounded like if would be quieter than some of the other options (except maybe the 300 muffler). I'm real happy with it, it's definitely louder, but more of a low toned thump thump thump.
I was going to try the cheap 300 muffler route, but every one I saw on ebay ended up around $130+. Spending that much money, I'll put it towards a slip on. I got my Q4 for $280 from a buddy at his parts unlimited cost. If I were you I would try the inexpensive stock 300 stuff.
Have fun Dan

 

As far a noise goes, the FMF Q4 is the quietest aftermarket muffler offered for this bike. I don't think anyone who has heard the Q4 after listening to the likes of the Muzzys, BG, Two Bros, HMF and Staintune could argue with that.

The stock can weighs quite a bit, compared to any of the aftermarket cans. I can't tell you how much the KLX300 muffler weighs, but there are one or two members of this forum who would know. I have heard that the stock 300 can isn't all that quiet, even with the 'butt plug' in, so I'm guessing the Q4 might be even quieter than that.

None of the above are as quiet as the stock can, but the Q4 is noticably quieter than any aftermarket option. I've been told that it has some bark when opened-up, but nothing near the level of the other options.

 

Thanks for the weights. The Q4 is ~32% lighter, but I'll try the KLX300 route first, if I can get the parts.

 

I have a Full FSW system with my 331 and I also still have my stock 300 exhaust. A buddy of mine has an FMF Power Core 4 with a FSW header. In comparison the stock Klx300 exhaust is the quietest, with but plug removed and an aftermarket turn down tip. It also makes good power. It is noticeably louder without the turn down tip as how some people run it. My FSW system is the next loudest and then the FMF Power Core 4. I also have a "quiet tip" that I have never even tried which may make it quieter than the stock exhaust. IMO, especially with the 331, you need a better header than the stock KLX300. The header is going to choke you up. The biggest bang for the $ is a FSW header mated to a KLX300 exhaust. I have seen many 300 exhausts on ebay over the years sell from about $9.00 to $50.00. The turn down tip is often more than the exhaust unless you make one yourself. Another advantage of the 300 exhaust is you will never have to repack it like an aftermarket exhaust. I also have cams in mine but the biggest and best "engine mod" for the KLX is an FCR35 pumper carb. I would rather have a 300 with the pumper carb as opposed to a 331 with a stock carb any day. I have had both set ups.

 

Good information. How does one come across a mikuni carb these days?

 

Loud pipes save lives. I have to say that because my pipe is so stinking loud!!!

 

Carb parts wharehouse

 

I'm partial to the Keihin FCR35 from FSW for the KLX. If you want to save some money and use a Mikuni, I would probably go with a modified Bill Blue carb. Both of those would be set up ready to bolt on. The FSW FCR will be jetted real close if not spot on. I got the impression the Bill Blue carb is not jetted, but the jetting specs are probably on the forum somewhere.

 

Cool thanks