Gas mileage with aftermarket exhaust and rejet

[zipnsip]

So I am thinking about installing the Vance and Hines exhaust and rejecting my carbs, but with gas expected to be $5.25 by Memorial Day I am starting to question myself.  Those of you that have an aftermarket exhaust and rejet what kind of gas mileage are you getting after those mods?  If the drop isn't too horrible I am going to do it!

[Kijona]

What year bike are we talking about?

It's advisable that you change out the pilot jets on the older models to #40's. It won't really affect gas mileage, and it'll also allow you to spend LESS time warming the bike up which means your gas mileage may even improve - if not but a slight amount.

[Funderb]

I get about 43ish with a K&N lbox, the max size jet dyno-jet kit, and a performance exhaust with no baffles. (essentially a fancy glass pack)
Its still a little lean i think....
Im still trying to figure the best driving habits.


mines a 98, so, the 2 jet system.

[XealotX]

Even at $5.25 a gallon the money you would save by NOT installing a new exhaust would pay for hundreds (maybe thousands) of miles of riding. Something to think about.

[Paulcet]

I get 47mpg on my 10 mile commute, 55mpg at 75-80 on the highway, better than that if I keep out under 65.

[zipnsip]

Sorry I should have included the year. It is an 09.

[Kijona]

Even at $5.25 a gallon the money you would save by NOT installing a new exhaust would pay for hundreds (maybe thousands) of miles of riding. Something to think about.

+1

I didn't even think of this but he's right. Just allocate the money you'd spend on that exhaust...for gas. It isn't as if a new exhaust system is going to be that much better than what you have. Plus, if you're talking about the full V&H system, you'll need to remove the header partially every time you want to change the oil. The cost, minimal performance gain, and inconvenience of having to remove it to change oil, pretty much precludes any notion I have of putting a V&H system on my bike.

What you can do is upgrade your jets to the recommended sizes for whatever you already have and that will do more good than messing with the exhaust. Here's the jetting information if you don't already have it: http://wiki.gstwins.com/index.php?n=Upgrades.Rejetting

[Funderb]

Or.. if you go the cheap way, like I did;
I could have saved....


four tanks of gas.

If you really want an exhaust thinger, want it for a cool new sound to the bike, not for performance, because likely, you wont find any appreciable gain, it will get torquier, and maybe faster, but it wont be a cbr600rr.
And you will find a loss of fuel mileage.

Go lurk craigslist or something for a slip on that you can have a muffler shop fit to the bike. Its a better bang for the buck. I paid $60 including the can and muffler fab-up.