Do I need to rejet after slip on mufflers?

[modifiedamerican]

I have a kz750 twin and my mufflers are rusting out. I bought some dunstall replica mufflers with removable silencers. My question is, will I have to rejet for just the mufflers? I really hope not cuz I don't know how to rejet it. Thanks everyone!

 

[Bozz]

The answer, like with most things is, "it depends".


If the characteristics of the new mufflers are close to the old, you might well be OK.


However, the odds are against it.


You should at least double check it because running the bike too lean for an extended period of time frequently results in very bad things.


A reputable shop with an Exhaust Gas Analyzer (EGA) should be able to set your carbs for your new pipes without much hassle.


If you have the cash, it really is the right way to do it.


It can be done without an EGA machine, but that tends to take a lot of time (but less money) to get it right.

 

[AlphaDogChoppers]

As a general rule, rejetting is not required with just a muffler change. Also as a general rule, bikes run lean from the factory, and rejetting almost always makes them run better.

Changes to the intake make a much greater change in fuel mixture than does changes to exhaust.

 

[Frog]

Give it a good run, if it still runs as before throughout the rev range and there is no more pinking than usual it should be okay. Standard jet settings are set up to meet environmental standards rather than getting optimum performance, so there is room for play. I've run bikes with slash cuts, Dunstalls and pea shooters, usually without re-jetting, if you change air intake as well that's a whole new bugger, suck it and see, good luck.