Help me understand what they do....

4 Into 1 Exhaust Benefits over a 4 Into 2 System:

Firing order 1-2-4-3 This means that the left two cylinders fire, one right after the other, then the right two fire, one right after the other. Therefore each "side" of the 4 into 2 system has quite uneven timing on the exhaust pulses - not so good for scavenging.

The 4 Into 1 arrangement has perfectly even spacing between all the exhaust pulses, since all 4 pipes come together. As one cylinder fires, it "sucks" the next cylinder's pulse along, etc. Best scavenging arrangement = less back pressure.

Also as JMKHZI mentioned, many of the stock systems have dual pipes - a smaller pipe inside the outer pipe. This is done to keep the chrome from turning blue. The trouble is, that that inside pipe is smaller in diameter ( about 1") than a good 4 Into 1, which has about 1 1/4" pipes. Again, more back pressure.

I have tried both systems on my bike. The 4 Into 1 system produced significantly more horsepower than the stock system, but it hurts gas mileage slightly, (perhaps 5%). As the 4 Into 1 system better scavenges the cylinders, it also pulls some unburned intake mixture into the exhaust during the valve overlap period - hence the poorer gas mileage.

N0NB wrote:

l0g1c wrote:

N0NB wrote:

In the January 1983 issue of Cycle World Technical Editor Steve Anderson takes on the topic of intake and exhaust modifcations in the article "In Search of the Free Lunch". It runs six full pages and a column on the seventh. If anyone is interested I'd be happy to scan it and pass it along.

I'd very much like to read this, if it's not too much trouble. :woohoo:

It is scanned and posted on my web host . It's about 3 Megabytes and 7 pages as a PDF.

Thanks! Snagged and reading. Will pass it around to my motorcycle buddies.

but there is one thing to remember about all this info i t irelavent to the older machines 2 or 4valve air cooled motors but not really currant with the advances in air box design that have taken place over the last 15 years or so.

650ed wrote:

clutch wrote: "The idea behind better fuel economy, and also the reasoning that K&N and other aftermarket intake companies use to justify better fuel economy is this:
Yes, more air, more fuel, more power HOWEVER, you are increasing horsepower and therefore get better fuel economy because under normal driving conditions and at cruising speeds (not trying to beat the guy with the Harley style of driving driving), you use less fuel because you are getting more power, you must throttle back from where you would have prior to pods to sustain your speed."

I respectfully disagree. Following that logic, a blown and injected 426 Hemi would get extraordinary fuel economy compared to a Ford Focus if they were both driving along at 55 MPH in top gear. Ed

any increase in efficiency should also mean an increase in fuel mileage at same speed in my simple little mind anyway,the motor is not working as hard.

timebomb33 makes a good point. Manufacturers have learned a great deal about how to design intakes and exhausts that are very efficient, inexpensive to manufacture and that will pass the ever-increasing government regs.
However, small but noticeable gains in power and weight savings can be had on older machines, like KZs. The full potential of pods and aftermarket pipes can be realized only with significant mods to the engine such as cams, pistons, port work and the like.
I would also like to take exception to 650ed's criticisms of pods. I have (and know others who have) ridden my pod equipped bike in 30+ mph crosswinds and rain so heavy that cagers were pulling over and my bike never missed a beat.
Yes, you have my permission t question my sanity now.

i run k&n's on most of my bikes that see street use and i myself have never experianced the problems that some people have talked about but even if i had the inconvinence of that would be more than made up for by the ease of carb removal a nd the fact that i can clean the filters if need be. the older stock air boxes are a pain to deal with and it is not worth it to me to have some thing that does not work the way i'd like it to . if i was restoring a bike for show i would leave them on but since none of my bike but one is stock i will go with pods on the rest.

OK how's your sanity? The old "your experiences may differ" apply here. I have heard testimony from very trusted and very experienced people that they have had bad experiences with pods (I am one of those people). I have also heard the same type of trusted experienced riders say they have had nothing but good times from their pod equipped bike. Can't tell you why. But I will say, having removed an airbox and re-installing it, that I will not do it again unless I'm doing a restoration. I will also opt for the airbox. I believe if you are going to remove a perfectly good airbox and replace it with pods you should just know how it might affect you and your bike. There is a possibility you will love them and a possibility you will not. But both possibilities are very real. I also think it's fair to say that those who do opt for the pods do have a more difficult time getting them right. Adequate is one thing and right is another thing altogether.

your are right i just have alot of experiance using them and setting up carbs for them so i stick with them it is nothing for me to take carbs on and off a few times to get things right and a lot of people don't have the time or energy to monkey with things so they settle for the adequete. i also have accsess to dyno's and ega's to help with the set-up if need be and most people don't.

Timebomb33 - you mentioned being able to clean the filters as an advantage? Not trying to start a war, but wouldn't is be easier to remove and clean a single K&N filter from the airbox than removing and cleaning 4 filters from carbs? I've always found the air filter on a KZ650 to be very easy to remove - no tools needed. Ed

yes that is true but most people dont buy the k&n type stock replacement if you give them the option of the k&n or replacement paper they almost always seem to go for the inexpensive paper one from what i've seen over the years anyway.

Here is an interesting excerpt from the article I scanned. Interesting to me, at least, since it tends to agree with my philosophy.

he is right about most of the things he talks about but even still i prefer pods because of the ease of maintaining the carbs and the engine.nothing worse than trying to stuff carbs into dried out hard intake manifolds then trying to get even harder air box boots to line up properly so you can get them clamped on so no dirt is going to get in the throats of the carbs.not every body is willing to spend the extra money to buy intake boots and air box boots after they just paid to have there carbs cleaned and because they forgot to pull the battery out and it froze and had to replace that as well and an oil change and tuneup because they neglected the bike the last few months before they put it away for the winter and possibly a new tire because it could wait until spring for what is to alot of people a commuter bike. so it is not something that most people want to spend a lot of money on. probably not gonna happen