Exhaust options

[Guest]

I have the stock 4 into 2 pipes on my GS750.
I want to keep the headers, but put a longer mid pipe and a nicer muffler on it.
I would like to do this without having to re-jet.

Any suggestions on what muffler I could use?
One that provides approximately the same back pressure.

I don't think a longer mid pipe would change anything.
It needs to be longer to allow bending it up a few degrees.
And the muffler is bound to be shorter than the stock megaphone.

This will be a later date project, but I'd like to know what to get, so I can start watching out for the best deal.

While I'm talking pipes, can a single header pipe be replaced, without have to buy the entire set?
My outer pipe on the right side is dented up pretty badly, where it goes down and bends under the motor.
It's still free flowing, but also highly visible. The other three pipes need cleaning, but aren't damaged.

Thanks for any info.

[TheCafeKid]

You're not going to find anything out there that won't require some degree of jetting changes. These carbs I'm doing are going to be set up for stock. On the early 750s all four down tubes were separate pipes unlike the later models where the pipes on the outer cylinders were welded to the muffler section. Meaning yes you can replace just one dented down pipe. However if you're going after the look I think you're going for with the mufflers kicked up in back ala an old norton or something like that you're going to run into trouble with the stock set up pipes because they aren't designed in such a manor that adding mid pipe is really possible without cutting and welding...and having someone that can mandrel bend tubing of that size if you want it to look good. Muffler shops use a bender that will leave "wrinkles" in the metal. Ugly. Anyway, if or when you change things get a hold of me and I can probably walk you through jetting changes to a point. However I would encourage you to run it stock for a bit to get a feel of what it should feel like so you know.
And By the way I may have a tank for you if yours ends up irrepairable.
Lemme know.

[duaneage]

I disagree about rejetting requirements. If different mufflers offer a reasonable amount of any back pressure the scavenging of the cylinders won't change much and volumetric efficiency will remain the same.
The only way to know for sure is to test it. Make any change on the airbox side and you'll need to rejet because it affects the carburetor's ability to meter gasoline properly in response to load.

A good starting point is to up the jets one or two sizes and then take it down and see what the spark plugs look like after a hard run and chop.

[ValorSolo]

I'll be running stock for a while. I'm not doing anything else major to the bike until I get to ride it a few months.
Then I'll have a better idea of just what I want to do to it. I'll only add whatever I need as issues arise.
I'll also be running the stock airbox, properly sealed and installed. I've already replaced the boot o-rings and my boots are good.
I can actually weld a bit with my wire feed, I've done exhaust pipe before. I could probably handle any welding needed.
Wouldn't filling the mid-pipe with sand help with wrinkling during bending?

I've put a temp fix on my tank until I find another one. So I may get with you on yours.
Last night I had this idea about getting a replacement tank and then modding this one.
And since then, I've put gas on that fire, and it's a blazing notion now instead of just an idea.