the Zen of exhaust swapping....

[powaw]

I have been reading alot about exhaust systems for the 400ex and want a quieter one (I have FMF pwrcore 4). It seems that if you want performance that you have to have the noise. I guess it comes down to flow=HP. I also hear that a chambered muffler cann't be beat for sound supression. So my question is has anyone ever swapped stock mufflers? Say get a Raptor pipe and mount it on a 400EX. It should flow better than the 400's right? I mean it was designed for like 165% more exhaust flow than the 400's stock pipe was, but yet it still has a chambered design. What do you guys think about this idea? Legit or not?

LeRoy

[powaw]

:huh so what does everyone think about this idea?:huh

[Chef]

Try it, what have ya got to lose? The Raptor exhausts were really restricting though...Maybe try one from a DS?

[powaw]

was think about using a Ds exhaust but there aren't any on ebay right now. A couple of raptor pipes though. Does anyone know the head pipe OD on a raptor or DS?:huh

[400rednEX]

there's 2 stock ds650 silencers in my shed but i don't know if my brothers want to get rid of them. better info though is that one of the ds's has an ungodly loud white bros. e-series on it (the q-core doesn't help much either) , and the other one has a power core 4 on it with the quiet end cap on it and it is pretty quiet, sounds great, and they run head to head in a drag. they are set up very similar.

[powaw]

Would you ask your brothers if they might want to get rid of one of the stock pipes in the name of science?:p

[powaw]

Anyone else have any ideas on the topic?

[RMX500]

sounds like the poor mans zen. stock pipes are heavy anyways.

[powaw]

True. They are heavier. I bought a stock 400 pipe of ebay last night. It's heading for the disection table.:eek2:

[markk]

I took my stock 400ex silencer, and pulled everything out of it and cut it down to about 7 and 1/2 inches and rewelded it! IT's louder than my white bros. full system, but i could really tell that i lost all sorts of power! (put a flowmaster 40 series under the ex) joking! they are chambered

[powaw]

maybe a Borla pipe. They sound good on cars and use a disk system. What should I expect to find in the stock pipe?

[400exdad]

I like my modded 400ex muffler. It is still really quiet but I think it does flow more air. I left my spark arrestor intact because it does most of the work quieting the noise. I know from experience here. :D or :( Anyway, the size of the hole in the rear chamber makes a big difference too on sound... I would start out small.. however, I ended up closing mine back up some after a little trial and error. Have you seen Gabes pipe mod how to? If not, it is easy to find with a search. I think his name on here is 86ATC250R. Good luck with the muffler and sound issue... I've been dealing with it for awhile now and have decided to stick with modded stock.

[RMX500]

some of you need to realize you're gonna lose back pressure and smoke your valves...

if your quad was EFI could pipe it like that..

[400exdad]

Smoking valves.... I don't think so..... Look at some of the straight thru exhausts that run in the upper RPM range, plus have bigger headpipes... Modding stock exhausts and keeping the noise halfway decent will have plenty of back pressure. If I'm wrong educate me please. BTW what does EFI have to do with exhaust?

Here's Gabes pipe mod:

http://home.earthlink.net/~gellett/exhaust/index.htm

[RMX500]

you can't just straight pipe a quad.. you'll burn the *** off your valves.

if you COULD straight pipe it.. there would be almost no market for exhausts.

[hondarider2006]

Had a friend straight pipe his 400ex. Ended up putting the stock silencer back on....Burt up his valve seals and rings. Can't even ride behind him anymore because of all the smoke, it makes me sick. Sure you can straight pipe it, but in the long run its only going to cause damage.

[powaw]

How are we defining a straight pipe? What is the length of it. I would think that you could call my stock head pipe and power core 4 a straight pipe technically. There aren't any chambers or anything to resist flow. Not that I would put on a straight pipe, but I am quessing that it is somewhat shorter than a normal length exhaust. Isn't it cold air getting to the exhaust valves that does damage anyway?

thanks for posting the stock mod!!

[400exdad]

Originally posted by hondarider2006
Had a friend straight pipe his 400ex. Ended up putting the stock silencer back on....Burt up his valve seals and rings. Can't even ride behind him anymore because of all the smoke, it makes me sick. Sure you can straight pipe it, but in the long run its only going to cause damage.

Cars runs straight pipes all the time without problems... even lawnmowers. I've always felt or been told that as long as you keep the cold air from rushing back in on the valve seat you will be okay. I wonder if your friend didn't ride without a pipe at all, or since he was "goofy" (no offense :) but they do sound like cr@p and probably hurt performance) enough to ride without a silencer or spark arrestor at all, I wonder what his jetting looked like while riding with just the straight pipe.

[400exdad]

Originally posted by powaw
thanks for posting the stock mod!!

No problem. While it is still limiting the performance, I am happy with it.

Heres a pointer that I learned from Leo, the old site administrator, use an arc welder, crank the amps up and burn the hole(s) in the back chamber. Also, use an air hose and a lot of shaking to get all the old slag out of the muffler.... that debris can rattle pretty good! :cool: