Single or Double Exhaust [Archive] - Kawasaki Motorcycle Forums

Single or Double Exhaust

schedMas
11-22-2011, 02:10 AM
Hello everyone, i just got myself a 1997 ZX11R, my second Kawasaki (my first is a KMX 125 off road), previous owner modified the exhaust from double to single, gave me the spare exhaust and i'm thinking of putting it back, quite concern on the tuning of the carbs if i would be putting the other exhaust back, previous owner had the carbs adjusted to lean, also thinking of putting 1 inch heli-bar risers. what do you think guys?

martin-csr
11-22-2011, 09:09 AM
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schedMas
11-22-2011, 10:02 PM
Kinda complex martin-csr, the previous owner gave me the old headers with the other exhaust still attached, it is made of carbon steel painted silver and i'm not sure if its the original, he replaced the headers with stainless steel and had it 4 in 1, am planning to bring the old headers to a muffler fabricator and have the 1 in 2 layout and measurements copied using stainless steel and have it welded to the installed stainless steel headers currently attached on the bike, problem is whether the old headers are the original ones for me to have it copied in terms of the angle of the bends and diameter. also noticed that the old exhaust still has restrictors or buffler attached at the end while the installed exhaust has none, they are the same vance and hines aftermarkets. And will surely work on your advise, i have the old plugs with me which the previous owner replaced after replacing the pipes, would just get the specs of it and get new ones. another factor is when it was converted to 4 in 1 it is much shorter, length factor is another issue. will post an update asap, safe riding

martin-csr
11-23-2011, 09:47 AM
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sfair
11-23-2011, 12:56 PM
This area is soooo complex that simple eyeballing and a few measurements will not do the job.
There are so many variables that affect exhaust efficiency and required carb tuning, that only a dyno can solve.
That is why a bike that has been modified without solid engineering can be a nightmare.

schedMas
11-23-2011, 08:40 PM
Yes i agree, reason why i like to bring the bike back to its original engineering, with double exhaust, the Japanese have spent years of research, design and testing coming up with the these wonderful bikes, and with just a flick of a finger alter the design and engineering? I'm really not comfortable with the single exhaust, appearance factor the bike is not balanced, there something missing on its left side, plus the weight distribution factor, bike weighs 500lbs, i weigh 225lbs, couple of pounds on one side definitely there is an effect both on the bike and rider. Dyno testing services is quite hard to find here in our place. The Kawasaki company here only focuses on sales of what we call underbone bikes (100 to 200ccs) and bikes come here semi knocked down from Japan. I'll try giving a shot on the old carbon steel manifolds hoping that they are the original ones, have them temporarily re-installed together with other v & n exhaust and test the bike, get some tuning done and if all is well, have the manifolds copied exactly using stainless steel, seems lots of work ey, thanks for the advise martin and sfair, will post some updates asap, safe riding

klx678
11-24-2011, 07:30 AM
It's all about flow. That can be achieved easily with a free flow single exhaust - but quite loud. The factory stock exhaust will have two mufflers because to get the flow they want it with the sound level they need there has to be a large amont of volume in the mufflers due to the restrictive baffling. I'm betting the stock system may flow as well as the header due to the dual muffler volume. The biggest reason for a header on a supersport will usually be to lose weight - those things are heavy. Anymore, most headers only gain a few horsepower over the stock set ups, but they can cut like 20 lb from the bike fairly quickly. And some sound fairly good if not obnoxiously loud.

sfair
11-24-2011, 10:55 AM
It's all about flow.

It is not quite that easy. Pipe diameter, length, cross-overs,(if equiped) all have a major influence over exhaust efficiency. Poorly designed exhaust systems can have wild effects on the torque curve; having influence over horsepower, fuel milage and driveability. A large pipe,short length exhaust may flow tons, but will have a negative impact on the tune of the engine. When one purchases an aftermarket system, hopefully the manufacturers have done their engineering and homework on a design that provides positive benefits and not just eye candy and noise!