Muffler Swap

[Dupo]

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:

[Dupo]

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:

[jokerbluffer]

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?

[Dupo]

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.

[jokerbluffer]

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

[Dupo]

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".

[Dupo]

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.

[jokerbluffer]

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?

[Dupo]

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.

[bigfour]

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.