Effects of 4 into 1 exhaust

What would the performance effects be of going with an aftermarket 4 into 1 exhaust system to replace my current stock 4 into 2?

Would rejecting be required with most of the aftermarket (performance) systems out there?

For me, there's only one choice....
Not sure of the bike, look, sound or performance your looking for...

OMR

I suspect that most folks go with 4 into 1 systems just to replace stock systems that have rusted out or been damaged in a crash.

Unless you're going to get into several other areas with other modifications the biggest difference will be a reduction in weight.

If you change the intake and rejet the carbs you will probably see an increase in horsepower, perhaps in the 5% region. This usually comes with a loss of overall driveability.

To answer your last question: Changing from a stock system to an after market system almost always requires rejetting.

Regards

KZCSI

Similar look but Vance Hines...


This brings up an interesting subject matter, in review of old postings a lot of you had troubles (mounting) the Vance Hines systems.. Is this still an issue with their pipes?

Any reports on longevity, performance etc... Can't beat the price!

Yes, with a good 4/1 system you will need to rejet. If the system states "no jetting reqired" then you"ll get nothing out of it except noise. I'm lucking enough to have a classic Kerker on my bike that I paid $199.00 for 27 years ago. Here she is freshly intalled back in 1981...

I got a Kerker clone for my 750 way back when. It gave more power even with the stock jets, but it ran even better with a larger main jet.

Bountyhunter,

What's a "Kerker clone"?

Is this the Vance Hines or some other brand that has the looks of the Kerker...

Manufacturer name please...

OMR

Alright - as far as driveability - what characteristics will be different? Big reduction in bottom end? etc

Can a 4 into 1 system be installed that utilizes a muffler than can be tuned (for sound, flow, etc)?

With just a 4-1, and stock everything else, you should rejet a few main jets larger(Stage 1), but spark plug color will tell you that. If you use just K&N Pod Filters, and a stock exhaust, Stage 3 Jetting is recommended. With both Pod Filters, and 4-1 Exhaust, with the proper jetting, you'll notice increased midrange, and top end, with a little loss down below, but what you do notice, will increase the fun factor.

Just stock 4-1 you might notice a better sound.

This is just my opinion though. Others might say something different.

Old Man Rock wrote:

Bountyhunter,

What's a "Kerker clone"?

Is this the Vance Hines or some other brand that has the looks of the Kerker...

Manufacturer name please...

OMR

I don't know who made it. It was the header sets sold by JC Whitney back in the 80's. Looked like a Kerker, kind of loud, really low price, goes like a bat outta hell. I still have it but got tired of the PITA because it blocks my oil drain plug... and it makes my aging ears ring.:blink:

bountyhunter wrote:

Old Man Rock wrote:

Bountyhunter,

What's a "Kerker clone"?

Is this the Vance Hines or some other brand that has the looks of the Kerker...

Manufacturer name please...

OMR

I don't know who made it. It was the header sets sold by JC Whitney back in the 80's. Looked like a Kerker, kind of loud, really low price, goes like a bat outta hell. I still have it but got tired of the PITA because it blocks my oil drain plug... and it makes my aging ears ring.:blink:

Sounds like a Jardin, megaphone is a little shorter than a Kerker and WAY louder, a real "sharp" tone to it when you open the throttle. :ohmy: They were about $50 cheaper than a Kerker.

My experience tells me that MOST aftermarket pipes for vintage bikes don't flow significantly better than a stock system and thus don't require rejetting. I can't say this is true for every system but certainly for most. The new bikes using newer and significantly more expensive aftermarket pipes do change tuning. Some make more peak horsepower where some cause flat spots in the powerband. The older style systems typically don't require rejetting and manufacturers recommendations don't mean a whole lot as far as rejetting goes. If you buy one, and the carburetors need to be rejetted, you will know it. You will either see a lean spot somewhere in the mid-range or will not be able to pull redline on top. Since you can check without much possibility of damage, I always recommend someone try the new system before messing with the jetting. It makes a lot more difference, on a vintage bike, to modify the airbox as most older airboxes are very restrictive. Putting some pods on requires significant rejetting.

I haven't bought many new exhaust systems over the years but the one that stands out as a good price/quality combo is the V&H:
www.z1enterprises.com/detail.aspx?ID=2050

I do have some experience with V&H, Kerker and Mac and can honestly say that the former two will fit and hold up better than a Mac system which typically isn't made with a lot of care. I have a Mac system on my KZ1000E1 as it was the only 4 into 2 in black ceramic that I could find. It was a chore to fit the system due to sloppy quality. Once installed, the system is OK and is what I was looking for in looks. I doubt it flows better than a stock system.