Jump to content
Sign in to follow this  

stupid question maybe? RE: exhaust

Recommended Posts

I was wondering what the pipe does. what would happen if you took off the silencer and just ran the headers? you probably wouldn't get the backpressure, right? Well, what if you could manufacture some sort of restrictor? If i recall, w/o the pipe at all, it is acutally quieter. if i was home, i would just try it, but i am at college with no bike, so i won't be able to test it for a good 3 months. :thumbsup:

thanks.

Share this post


Link to post
Share on other sites

Maybe I am not understanding the question. Did you really mean that with no pipe on your bike is quieter? I may be way off here, but I think that is what a pipe does, hence the term "muffler". And the restrictor idea in essence is what the pipe is, as little as possible. That is why I paid for that over priced thing anyway. If you do come up with a way, let me know, I will be in line!!! :thumbsup:

Share this post


Link to post
Share on other sites

like i said, i am not sure, because it has been a while since i have been around my bike, but i thought i remembered that it was quieter w/o the "muffler". In fact, my WB e-series is called a Pro-Megaphone type. i am guessing that there is something in regards to back pressure, and the length of the pressure wave, but it seems like it could be a neat idea...?

if someone wants to try, or at least let me know why i am wrong, please do so.

Share this post


Link to post
Share on other sites

Well my brother started his xr650r with open headers when he was switching pipes and it was loud as hell. At the races someones silencer fell off his predator and it was loud also. We take the silencer off our 2stroke blaster and it runs a lot better buts it pretty loud. We dont do it much. Just for a min or 2.

Share this post


Link to post
Share on other sites

I thought it screwed up your valves if you ran it without the pipe on?

Share this post


Link to post
Share on other sites

It very well could, it will run LEANER without the increased backpressure so you could burn an exhaust valve but whether it WOULD or not, I can't say- it's the bike's decision on that one depending how the carburetion is set right now. If your carb is a little on the rich side, you won't have any trouble but I don't think with no silencer at all, you would get the best performance. Just my 2cents.

Share this post


Link to post
Share on other sites

Im gonna pretend you dont know about that little Torx screw on the bottom of the back of the muffler. Remove that little Torx screw then remove the the 3, 8mm bolts that hold the scilencer tip on and (listen close) hold that part/assembly so that the screened part is closest to the ground/work bench and smash it like you would smash a scorpion with a rock (we have to do that every once in a while here in AZ)(yes you will smush the screen a little) the restrictor will pop out and you will have like a 1.25/1.5 inch opening. Straighten your screen and reinstall the shiney part. :thumbsup: It will be louder but it will also be faster. Keep an eye on your plug and adjust the carb/jets accordingly.

If you have done all this then forget I said anything.

Oh you could also build a resonance chamber with an adjustable length dead end. Use and oscilliscope to measure the frequency, use a tach to figure out the most annoying rpm at WOT. Calculate the exact amount of air excaping from the exhaust at most violating RPM range. Make the dead end tube (resonance chamber) the same volume. Put a "T" in line in your exhaust before it exits (one end from engine, one end to the dead end, one end out) and this will have very little restriction and silence or decrease noise at the specified frequency make the dead end adjustable (like a trombone) and you will be able to tune for other frequencies.

AZ

Share this post


Link to post
Share on other sites

:naughty:2fiddy, My 93 XR250L has NO torx screws and definitely not a group of three bolts anywhere on the exhaust. Mine has 2 bolts parallel with the ground. After you grind the spot welds on the sides my mechanical baffle comes out and I replaced it with a bigger Thumper Racing Stealth fiberglass packed insert but the mechanical insert that is stock is merely a piece of pipe that is small with nothing inside and under the muffler is only 2 separate plates that carbon builds up on and are servicable. So, what you say might be true on another year but on my bike your tip doesn't apply. I love your scorpion stories, how big are scorpions in your area? I've never seen one in the wild, only at zoo's and they aren't the same kind.

Share this post


Link to post
Share on other sites

wow, kinda funny you should mention this since I just got out of the garage trying to remove the baffle from my 96 250L. Indeed, no torx screws. The L's all have exhaust that is based on the pre 89 XR's I believe. Those little spot welds are a beotch to get out.

BT

Share this post


Link to post
Share on other sites

Thanks BT, didn't want to look like a newbie that doesn't know my bike(b/c I do know my bike, all though I am learning the others through you guys). The "L"s are definitely a different in a few ways I just had to get XR's only to send a different main jet b/c the "R"'s are different in the carb in a few areas too. What I did on the exhaust was to use a dremel and a tiny stone tip to get the welds off, but it was still a bear to get out and the Thumper tip was close clearances on getting the 2 screws started due to the thumper tip being bigger in size, so it was a little rough. I didn't like the stock pipe with no baffle at all sounded nasty.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:

Sign in to follow this  

×