Muffler Swap
 

If you are interested in swapping out your muffler to an aftermarket type here is my HowTo.

Requirements:

1. You will need a muffler with reducers. Requirements are that it can fit on a 1 3/8" pipe (usually the smallest reducer). EMGO makes several of these. You can find them HERE or HERE They MUST fit 1 3/8" exhaust and i recommend 19" in length. The EMGO Turnout muffler is what i used.
2. You will need to be able to weld or have someone weld for you.
3. A piece of 1 1/4" galvanized pipe (home depot carries these). Get atleast a 6" long one. They come in various lengths. Better to have more than less.
4. A sawzall or air cutter.
5. Bench or air grinder.
6. You will NEED to shim the needle on the carb. See the HowTo section of this forum.


You can do this one of two ways - With the exhaust on or removed. Your choice. Off = much easier to weld and cut. On = easier cause you dont have to take the exhaust off :cool:

Ok you've decided what you are doing with the exhaust. Good lets move on.

First you will have to cut that megaphone muffler off. Make your cut right where the exhaust ends at the muffler. Cut it nice and straight! Gently debur the cut with a grinder or file. Cutting at this spot leaves the 2nd (rear) heat shield mount intact. This is a GOOD thing to do so that you have the 'stock' look when the project is complete. ****You may also cut right BEFORE the mount to get rid of it as well. This is YOUR choice!! Leaving the mount gives it a stock look when complete...cutting it off may cause mounting problems but is still "doable" **** (i noted this section with ****)

Now that you got it cut off go ahead and turn the bike on and take a listen (you know you want to do it). :lol:

Ok, we got the muffler cut now its time to add our custom reducer or expander if your cup is half full instead of half emtpy. Get your piece of galvanized pipe and one of the reducers. Cut the galvanized pipe the same length of the reducer (approx 2" i believe) Dont use the threaded part of the pipe obviously. Now you have your expander to fit the new pipe!

Take your piece of galvanized pipe and slip it on the exhaust. ****Notice it wont go on flush because the 2nd heat shield mount is in the way. You will have to grind a notch into the pipe so that it slips onto the exhaust and flush at the tip (end). We notched it by using a drill with a cylinder tipped grinding wheel. ****(see in first step your alternate way of doing this). If you cut before the heat shield mount, your galvanized piece will slip right on.

Now break out the welder. We used a mig welder to accomplish this. This is probably the best route you'd want to take. Slip the galvanized piece onto the exhaust so that its flush with the end of the exhaust. Weld it all the way around the exhaust ... NOT at the tip (end) of the exhaust. Weld it at the front (facing the front of the bike, NOT the rear!!) ... this will hold it in place as well as prevent ANY leaks. Once its cooled down .... then proceed.

Now take your reducer and slip them onto the galvanized pipe (or into the muffler, i honestly cant remember lol. It will be obvious when you go to do this part). Then slip your new muffler on. Notice, if you left the heat shield mount on, that you will also have to notch the reducer and cut a tab off the muffler as well to slip over the heat shield mount! ... Now use the supplied clamp to clamp it down. Dont tighten it down just yet!!! On most of the EMGO mufflers they have a 7" universal mounting plate. Line one of the holes up with the old mount hole for the old muffler. Then cut the excess off and bolt it down. This may require you to bend the univ. mount plate a little bit before bolting down, but not enough to cause a hassle. Mine has a slight bend in it and we did it with 2 oversized pliers. Now tighten the muffler clamp down and replace the heat shield. If you cut the 2nd heat shield mount off .... the univ. mount plate might not reach!!! This is why its a GOOD thing to leave it and to notch the galvanized pipe and reducer/muffler!

Hoping that you did the needle shim mod to your bike prior to this (if not, do it NOW).... You will now have to get to your mixture screw. Adding any EMGO pipe gives the bike WAY more airflow and will lean the crap out of the mixture. Your mixture screw is on the bottom of your carb. If you look under there, you will see a brass cap pressed into the bottom of the carb. This needs to be removed. You can 1. remove the carb and drill it out (be careful not to drill the screw heh). Or if you have a dremel tool ... use the grinding or cutting wheel and grind it down. For mine, i gave the carb a twist with my hand towards me and ground it down with a dremel. I ground the aluminum housing and brass plug down till it fell out. Be very careful and go very slow with this process. You dont want to mess up that screw!!! You know you are there when you make a "hole" in the brass and can pick it out with a small screwdriver. I then took some sandpaper and a sanding wheel on the dremel and smoothed the aluminum housing out so it looked nice.

Now - the following is for MY BIKE to be used as REFERENCE only!!! I started out with a full turn counterclockwise to richen the mixture. After several rides out, the engine was still running hot and backfiring/stalling every so often. I gave it another 1/2 turn counterclockwise and now, its running perfectly! So for reference only, i went 1 and 1/2 turns counterclockwise to richen the mixture up and get the bike running like it should. This may vary with your bike, so again, this is for reference only! When the GZ runs lean, it runs HOT. It also backfires sometimes and stalls when you try to go from a stop. If you have that, its still lean. I noticed when i got it 'right' that the muffler sound got deeper also (as well the backfiring stopped, it ran cooler again and no more stalls). Those are a few things to look for when tuning your mixture.

After you are all done, take it out and enjoy your aftermarket muffler and new sound!! :2tup:

Time taken to do this: 1.5hrs
Skill Level: If you have the tools or know someone who does AND know(s) how to use them i'd rate this Intermediate. If you dont, Advanced.

Any questions comments .. post away!


Finished Project:

http://upload4.postimage.org/784386/P7100167.jpg
http://upload4.postimage.org/784387/P7100168.jpg
http://upload4.postimage.org/784388/P7100171.jpg

Heres a sound byte of my GZ with the muffler on.

First is the choke on then the nice glug glug idle.

Download the MP3

:rawk:

What does the needle and the aftermarket muffler do for the performance of the bike? Is there a noticeable difference in power? Basically is the performance worth the cost?

Well for me i think i had a little more power than stock. I could pull up hills without downshifting like most say they have to do. Mostly the needle is to richen it up a bit from stock and the muffler is more to make it sound loud rather than the putt putt stock megaphone muffler.

What is the size of the pipe once you cut off the muffler? Is the exhuast header to small for the new muffler?

I dont remember the exact size of the stock pipe, i think its 1 1/4". No one makes an aftermarket muffler for that size. Thats why there is the need for welding an 'expander' to the stock pipe to bring it up to 1 3/8".

Keep in mind when choosing a muffler:

The longer the muffler, the deeper the sound. Although you are putting a loud pipe on, you are still putting it on a single cylinder 250 engine. Dont expect it to sound like a harley or cobra jet dual exhaust! It will be loud for sure, but wont give it the dual exhaust sound like bigger bikes have. I was pleased with mine for sure. People did comment on it alot.

I didnt do this when i did mine (thought about it then sold the bike and never got to it), but i was going to get the EMGO muffler that has the removable baffle that can be wrapped. I was thinking that maybe being able to wrap the baffle, would deaden the sound a bit to get rid of the popish sound and bring it down some. Also, you can pack it as much as you want to get a different sound out of the muffler.

I have seen a similar muffler that EMGo makes by Helix Racing. Instead fo being 19" it is 20". In my opinion, I think it might even look alittle better. Also, on JC Whitney they have mini-mufflers for only like $8 so that could really change the sound. I have noticed since I shimmed my needle the bike has been alot quiter, is this normal?

Yea ive seen those mini mufflers, they will probably give off a higher pitch than the longer ones. Ive also seen the Helix one as well, that was a nice looking pipe.

As for the shim, i didnt notice a quietness afterwards.

The exhaust you bought, was it a straight pipe... no baffles? If you started the bike before welding on the new muffler, was it too loud (ie. loud enough for a cop to pull you over)?
You see, I might try to make my own straight pipe for the GZ (that'll fit the 1.25" hole), but I'm worried it'd be way too loud or it'd be too lean to fix with a needle shim and mixture adjustment.

Its a straight pipe about 19" long. Its got a built in non-removable baffle - its not much of one, but theres one in there.

Yea starting the bike with the muffler cut off was loud.

If you keep the pipe at 1.25" throughout ... it will probably have a higher pitched popping kind of sound. The bigger the width of the pipe at the end .. the deeper the sound. Thats why if i had kept my GZ i probably would have swapped out for the pipe that you could 'wrap' the baffle to deepen it up a little bit.

This mod makes the bike louder, but if you pulled up to a straight pipe harley, you wouldnt be able to hear yours idle.

If you download the mp3 a few posts back ... you can hear what it sounded like on idle.

Additional pictures and information
 

I've just finished my new muffler installation as well (using the same EMGO turnout muffler)

Here are some additional pictures that might help those who are planning to do the same mods.


http://upload2.postimage.org/464389/cimg0742.jpg
Here is a picture of the pipe with the factory muffler cut. Notice that I cut just at the edge near the weld point of muffler and pipe. Be careful doing this cause you might cut the original pipe as well. The filler pipe (1 1/4") I bought from Home Depot was already cut and sanded outside.


http://upload2.postimage.org/464402/cimg0744.jpg
Here is the pipe again with 4 1/4" cut from the end. Why? The EMGO muffler will not fit if you don't shorten it. The end of the pipe will hit the baffle with 3" margin more from end of muffler to welding point. To make sure that we have enough space, I cut using that length (again, 4 1/4") off the original pipe. The filler pipe was already inserted. Like what Dupo has pointed out, you need to grind the inside.... and you need to grind "a lot". It took me 30 minutes to make it fit. I've used some WD40 so I can easily slip it on. So far, I don't see any negative effect with using that process when I started and run my bike.


http://upload2.postimage.org/464507/CIMG0743.jpg
Just to show you the tools I've used.

I had the pipe welded by a local mechanic (cost me $25). That price includes welding the filler pipe and spot welding the biggest reducer into the pipe filler. I did not have the new muffler welded in, but even so, it holds properly in place and doesn't vibrate when riding or even budge if you try to move/pull it by hand. Just tighten the clamp and your all set.

Also, a note with the reversible hang-mount of the new muffler... whatever hole you are going to use to mount the muffler to the frame (I use the 2nd hole from the muffler mount)... drill it with a #10 or 3/8 bit to make sure the bolt fits in or you'll damage its thread.

Just to warn you guys, the new muffler is "way too noisy". We can feel our pavement shaking when I start my bike on full choke. I'll try to compare this noise with my friends' Hayabusa tomorrow to see if I over did it. Anyways, with the filler pipe, I/we can buy another not-so-noisy-but-has-some-thump-sound pipe that can fit 1 3/8", which has a lot more selection than 1 1/4" (which is none at all).

I told you it was loud lol.


Nice write up!

Hi, folks!

I'm going to install one of these exhaust mufflers. They suit from 1 5/8" to about 1 2/5".
http://i24.ebayimg.com/03/i/000/9c/91/8f10_1.JPG

Now I've been looking to your photographs and I've seen big diferences between your headers and the ones in my bike.
There are several welded pipes with diferent thicknesses, the heat shield mounts are located at other places, and even the heat shield itself looks diferent. I don't know where to cut!

Here are some pics.

http://img.photobucket.com/albums/v2...r/exhaust1.jpg
http://img.photobucket.com/albums/v2...r/exhaust2.jpg
http://img.photobucket.com/albums/v2...r/exhaust4.jpg

Any ideas? Thanks!

Well if your pipes can slip on to 1 5/8" .. and your pipes wont stick out too far (they look long) ... then id cut at the 1 5/8" and just slip them on and tighten down. No need for a reducer then.

Just make sure your pipes arent too long if you mount them there.

Other than that, it looks like you got a "Marauder" gz250 for over seas and is different from ours in the US. You may just have to figure out for yourself how you are going to mount them.

Thanks! I think I'm going to cut at the first weld point, but I'll wait to receive the muffler, just in case I need another diameter.
I'll post pics as soon as I install the new one. It's more than 27" long... :yes:

Jaime, make sure you cut only the muffler... do not cut all the way through. Do not cut the pipe beneath the muffler. You can cut excess pipe after that. It is safer that way.

Yeah, I'll try to be careful, it looks easy to cut the inner pipe. :cry:

This afternoon I've been trying to swap the muffler, but there's no way to remove the stock one, it doesn't even move a bit! I've cut it properly but the muffler doesn't slip off the headers. :cuss:
Did your mufflers could be removed easily?

my '06 gz250 muffler's contact point to the pipe is that welded section. So after I cut the muffler from that part, the whole muffler slips off with no problem.

Do you mean the red arrow welding?

http://img.photobucket.com/albums/v2...r/exhaust5.jpg

That's the point that I've cut. I think that there's another welding point somewhere. Maybe that piece is an expander welded from inside too. O_o

We have a different muffler... but to show you where I cut the old muffler. Take a look at this:

http://upload3.postimage.org/64630/gz003_muffler.jpg

Legends:
* green area is the stock muffler
* red area is the pipe and up to where it is extended into
* blue line is where I cut the original muffler (again, I did not cut "through" the pipe... just the muffler so the pipe or red area still extends to the partial overlapped green area).

Hope this helps. Sorry if I don't make much sense in my explanations... (not a mechanic myself) :-)

Thanks, John! The picture is quite clarifying. :tup:

My bike's muffler is something different, but today I'm going to cut the blue arrow welding. I'm sure that it's the way to go.

I've finally swaped mine. It has a tiny "red area" so it was hardly fixed there. I've needed the -free- help of a local workshop. :blush:

http://img.photobucket.com/albums/v2...racker/alc.jpg
Stock muffler.

Here's a video.

Now the mixture is quite lean again and I can't go further than 75 mph.
I'll carb the bike soon. :tup:

nice! i like the new pipe you put there. That stock muffler has a lot of baffles... I would assume that it is really quiet before.

congrats with the mod!

Hey. That looks like the internals of a catalytic converter. The Euro bikes don't have smog protection, do they?

Well, the stock exhaust wasn't noisy, but not really quite at all.

About that grid, sure that looks like a catalytic converter, but a carburetted bike shouldn't have one... Maybe is there to acomplish Euro-2 specs. :??:

Re: Muffler Swap
 

Jamie,
How is the bike running with the new muffler and the jetted carb? Have you made any recent changes that you'd like to share? I will take on this project this spring and have found everyone's input very helpful and interesting.

Re: Muffler Swap
 

I am thinking of doing the exhaust on my gz250.

here is my question: There are two pipes that are joined together under the heat shield, has any one considered putting dual exhaust on their bike or is this a bad idea? and if it is a bad idea why? :??:

Re: Muffler Swap
 

Not a bad idea if you like to spend money needlessly. A single cylinder 4 valve head doesn't need separate exhaust systems for each exhaust port. The GZ works well as is, why take a chance on fouling up it's ability to make reasonable power and compromising it dependability.

Re: Muffler Swap
 

You probably are the first......to propose having MORE mufflers than the total number of cylinders.......on ANY vehicle !!! :shocked: :biggrin:

No, not a good idea because just DOING it would be costly and a big pain getting another one mounted so that it didn't interfere with anything.......like chain maintenance.
Then there is the sound.....which might be truly wierd.
Then there is the lost back pressure, which might necessitate jetting changes......if you haven't already.
Then there is the added weight.

The other thing that probably is a bad idea is modifying the air intake (filter) without changing the jets in the carb. Have you done that ??

Re: Muffler Swap
 

actually I did. I took the air flow restricter off. But I haven't had any problems at all. I know I should have adjusted the jets, but every thing I know about carbs (that isnt much) is that when you make a change see how it runs, make a small adjustment and try it again. If you make a change and it is still running fine why adjust the jets? Though I have been thinking about the jet mod that is listed on of the how to topics.

Re: Muffler Swap
 

If that's the little scoop that pops off......that doesn't count. It is not a restricter, just a diverter to prevent bugs and water etc. from entering so easy. Any restriction it provides is miniscule.

Re: Muffler Swap
 

If you took the restrictor off and increased the air flow, you would be running lean and hot, and then you have to change jets, etc, 'till you get it all balanced again.
All for very little gain, Best advice, leave it all alone and enjoy it for what it is, and you'll have no trouble with it.
Or if you do want to modify it, get some serious help and a lot more knowledge before you screw it up and then need professional help to fix it.

Re: Muffler Swap
 

hey i just got a slip on from jc and do i have to shim the jets or can i just change the air fuel screw to make it richer. and what is the pipe in the muffler that you say not to cut threw. plan on putting the slip on next week but need to get it all done one day. because this bike is my daily drive since i dont have a car.

Re: Muffler Swap
 

Welcome to the forum.If the muffler you got has a baffle in it you will only need to do a idle mixture adjustment.When you cut off the old muffler just make sure you cut behind the mounting holes for the heat shield,as you will be reusing it.Good luck.
:cool: :)

Re: Muffler Swap
 

You probably won't HAVE to change anything. If it runs good and idles good, you may not have to change anything with the carb.

The first clue will probably be that you have to leave the choke on longer before you can turn it all the way off. If that happens, or it idles rough even when hot......then you will need to adjust the idle mixture screw......and then see how it goes after that.

It would probably be best to cut the muffler off with the pipes OFF the bike completely.......to avoid breaking the mounts, shields or the studs in the exhaust ports. If you do that, start soaking the manifold bolts with penetrating oil as early as possible the day of your project (or the night before). Having a new set of exhaust gaskets on hand would be a VERY good idea too since they might start to leak even of you do NOT take them off.

WD40 is NOT penetrating oil !!

Re: Muffler Swap
 

thank you very much. i will let you all know how it goes i will put some pics on later

Re: Muffler Swap
 

go the pipe on runs great no need to mess with the carb yet. maybe once i get the the air filter. thanks guys

Re: Muffler Swap
 

You can get a filter from Hiflo-Filtro that is about half the price or less of an O.E.M. filter.Part#HFA-3503.It is listed for the GS500 but is a drop in.Many aftermarket suppliers don't list a filter for the G.Z 250,but list for the GS500.
:cool: :)