Getting a new exaust

[Guest]

i have a 1979 gs705e and it has a 4 into 1 header. I was wondering if i put dual pipes on it, will i have more power throughout the bike or just leave it as it?

[azr]

A 4 into 1 pipe gives a bike more power, IF the carbs are adjusted properly for the pipe, if they're not the bike may run like crap and have less power

[srg]

How does a 4-to-1 give it more power? I'm not questioning you, just trying to understand.

In my head, a 4-to-1 would increase the resistance in the exhaust (since there's one exit pipe instead of two in a 4-to-2). More resistance = more energy needed to "push" the exhaust out = less power to wheels.

But I may be misunderstanding something.

[650cafe]

How does a 4-to-1 give it more power? I'm not questioning you, just trying to understand.

In my head, a 4-to-1 would increase the resistance in the exhaust (since there's one exit pipe instead of two in a 4-to-2). More resistance = more energy needed to "push" the exhaust out = less power to wheels.

But I may be misunderstanding something.

I've often wondered this too. I dont question it to be true, all one needs to do is look at MotoGP exhaust systems and factory sport bike systems, but I dont understand how a (seemingly) more restrictive exhaust can provide better performance. My theory is that it may not necessarily provide the greatest outright performance, but instead the highest degree of desired performance.

[JTGS850GL]

It comes down to better scavenging of the exhaust gasses. This is especially true at higher RPMS. The exhaust pulses actually "pull" the gasses through the exhaust more efficiently at higher RPMs with some sacrifice at the lower end. This creates more of a vacuum at the exhaust port providing better evacuation of the cylinders. 4 into 1 exhaust also make it a little easier to balance the intake since all cylinders should be balanced equally. This is also true for a 4 into 2 into 1 system. This all assumes that the 4 into 1 exhaust is designed properly. There is also the potential for better cornering clearance as well.

[GelandeStrasse]

There is also the potential for better cornering clearance as well.

+ less weight

[650cafe]

+ less weight

was just gonna say that...thanks for the explaination JT...and everything you said confirms my theory...it's about making a certain kind of power...up high in the range where racebikes live. Exhaust/intake theory is quite complex and interesting. I remember reading an article in Cycle World with Steve Schiebe, the director of Harley's VR1000 program. He spoke about specific aspects of tuning, primarily using fuel injection, where he talked about attaining "best power", in which case in intake system would actually create pulse waves pushing intake mixture out of the engine, creating what is called "stand-off". Not sure if its relevant, but its interesting.