4:1 Exhaust vs 4:2

Can someone explain the benefits of going from the stock 4:2 Secca 550 exhaust to a 4:1?

I personally like the look of the 4:1, however is it worth the extra cost?

Thanks!

 

no benefit at all , also with 4 to 1 you may have to rejet I did not with my maxim.
I have a 4 to 1 off of a Yamaha but does not allow for center stand. it was on my seca I will post the part number off of the muffler.
then I picked up my fall project and it had a seca exhaust (on maxim) I am cleaning it up to put on the Seca.
the mac 4 to 1 exhaust I have on my maxim allows for center stand but you can not remove the oil filter housing from between the pipes you have to rotate it to remove filter.its 1 year old
I have another 4 to 1 exhaust unknown brand that required dropping the exhaust to gain access to drain plug, cant use center stand with it.

if you want to trade a mac 4 to 1 for a seca exhaust I would be open to that it needs to be repainted (header pipes) 1 year old , you need to make a bracket to hang it.
I have seen brackets from shock as a hanger, I use a flat bar from foot rest holder back to muffler. Header pipe at connection can be shortened an 1=1/2 " if you wanted to.

 

EXHAUST SYSTEM OVERVIEW:

As with many other systems on these bikes, the Yamaha XJ-series of exhaust systems are a mini marvel-to-behold, well thought out and engineered......so please do keep this in mind when considering aftermarket "performance" exhaust systems.

Let's start with the headpipes: many of them are actually of a double-wall design......and inner tube (that carries that gas) and an outer tube that can stay relatively cooler and thus maintains its appearance much better and longer. Additionally, they are tuned in their internal (gas-carrying) pipe diameter to match the flow characteristics needed for their intended use.....thus, for example, even though the headpipes for an XJ650RJ Seca can physically be installed onto an XJ700 engine, the inner pipe diameters do differ, and thus the swap may cause more harm than good, as it messes up with the balance of airflow thru the engine.

Pipe diameter helps determines (among other things) both the volume of exhaust gas that can be carried away, and, equally as important, the speed at which those gases will flow thru the pipe. All other things being equal, a bigger diameter pipe --- while surely capable of flowing more gas volume, will also slow down the progress of gas thru that pipe......which, in the world of exhaust gas flow --- and its important effects on intake gas flow (how well each cylinder can be scavenged of its burnt exhaust gases and allow for a full and complete incoming fuel/air charge) --- is a mighty important consideration.

By the way......although we've touched on some of the reasons above.....in regards to "swapping" headpipes between models, our best advice is: don't. Besides the whole "gas capacity and velocity" issues discussed above, there also the issue of fit: although the headpipes between a 550 and a 750 (for example) may look the same, and may actually bolt onto the cylinders heads, both their length and their unique bend angles ---- needed to follow the frame and mate up with the exhaust collector ---- will likely be different.


Next: the collector. Although these weren't used on the XJ650 Maxim and XJ1100 models --- those bikes use a crossover pipe to perform the same function --- the collector box performs a few not-so-obvious but very important functions, and does it in a very admirable manner. First, of course, it provides a transition between the headpipes and the mufflers. Second, it keeps the decibel levels down to a reasonable volume. And finally....and very important for overall engine performance.....it provides a method of assisting that all-important "gas velocity" by providing a sufficient volume of space for "warehousing" (temporarily) the exhaust gas volume, while also providing (via its unique design) the ability to assist in providing maximal exhaust gas flow.

If you've ever looked carefully at your heavy (and probably-rusty) collector, you'll notice that it is designed ("split") in such a way so that cylinders 1 & 4 (the outer two) "share" a certain internal cavity space, while cylinders 2 & 3 "share" the rest of it. This is important because of the firing order of your engine: 1-2-4-3

If cylinders #1 and 2 --- which fire sequentially (and, thus need to exhaust their spent gases sequentially) ---- were to share the same exhaust cavity, then their (sequential) exhaust gas flows would be "spaced" too close to each other (in time) and would see vastly different back-pressures (cylinder 2, which fires after cylinder 1, would see more back-pressure than cylinder 1, which emptied itself into a, well, into an "empty" exhaust collector).

To put it another way, cylinder #2 sees a lot more back-pressure than cylinder #1, because the gas pulse from #1 doesn't have much time to exit the system before the pulse from #2 is trying to squeeze itself in the same pipe. Notice that cylinders #3 and 4 have a similar situation.

The same thought goes for the other two cylinders (# 2 and 3). Notice how even the aftermarket "dual" exhaust systems suffer from the above problem, since they are really two separate system, one system being for cylinders #1 and 2 (left side) and the other being for #3 and 4. Notice how it's the "sequential" problem.....since cylinders 1 and 2 fire (and exhaust themselves) sequentially, and since those gases vent into one common chamber, that cylinder #2 is going to see more backpressure than cylinder #1 will......and same for #3 and 4.

This un-balanced situation....with different cylinders seeing different exhaust system back-pressures......can (and does) result in different amounts of burnt gas scavenging from the differing cylinders, which is not the way to get an engine to make the most amount of power.


Aftermarket 4-into-1 systems overcome this "differential scavenging" situation by re-introducing, somewhat, a "collector".......where the fours pipes come together into a common chamber, just before the muffler. This collector allows the system to maintain some amount of equalized back-pressure (and thus burnt gas scavenging), while the particular placement of the four headpipes, as they come into the collector, allows a little bit of "pull-thru" between each cylinder, helping to reduce overall system back-pressure levels, while still maintaining a somewhat equal amount of back-pressure to each cylinder.

Or, maybe, aftermarket systems do no such thing:

http://www.motorcycleproject.com/text/exhausts2.html


Of course, the final piece of the puzzle is the mufflers, which are primarily decorative pieces....they look nice, stylish to the lines of the bike, contribute almost no back pressure to the system, and provide a nice throaty (but not too loud or droning or buzzing) sound output.

So just remember that the real heavy-lifting in the exhaust system is actually done by the headpipes and the unique, well-designed (but often overlooked) collector box.

 

nice write up

 

I have a 4:1 setup on my 650 Seca I'd sell for short money. ¬.¬

 

It won't fit a 550.

 

Balls.

 

so the mystery 4 to 1 exhaust states for motorcycle YAM 2AX059 I do not know what bike that is. it is a fully welded exhaust .
part umber search came up empty.

 

That isn't a Yamaha part number, or the designation for a motorcycle model. It's an in-house part number for the manufacturer.
Is there a makers mark anywhere on the system?

 

I think a 2AX model is the FZ600's..............................

 

OMG did I have a brainfart. You are correct.

 

I don't care for 4/1 at all, personally

 

the muffler has on it
This Yamaha motor co ltd exhaust system meets.......
the 4 to 1 pipes , the flanges that secure it look like the ones on my seca exhaust just a little different , exhaust test port bolts.
looks like this ebay one black

 

Eeeewww

 

fugly as they get just a can on a pipe......
the only up side is you can not see it when you are riding and if you always approch the bike from the left side
I use it to hold down a tarp on my next project works well for that.

 

I like mine on the 650 I don't know much about it this is my first Street legal bike only had it about a week now I am noticing a few downfalls with it like it sits super low to the ground so unfortunately scraping is something that happens I love the new sound

 

The 4-1 you have does not look any lower than the stock exhaust. You might want to revisit your street riding technique, or look at the condition of your shocks to be sure they are not set too soft.

 

The rear end has been dropped 2 or 2.5 inches with some aftermarket shocks idk anything about them it wasn't my doing I haven't really been on it much so now that you that about the shocks it got me thinking and it very well could be too soft i noticed it scraping pulling in and out of my garage only when I was sitting on it

I don't have any good picks of the exhaust but it definitely sits lower than stock I'll try to get some better ones either tonight or tomorrow

 

You don't want that.

Looking at the pic on the centerstand, the rear tire is much higher off the ground than stock. Must be lowered significantly.

 

More than 2" of drop is not good for the u-joint. If the shocks have a spring perload adjustment, dial it up until you get very little sag when on the bike. Then save up for some longer shocks.

 

Neither muffler is lower than stock. Notice how the top edge of the cans are tight to the rear footpeg bracket? Right where they belong. It's what makes the stock exhaust look best on the XJ series. None of the aftermarket stuff I've seen follow the lines like stock. I would think about spending a few bucks to raise the rear up, unless you prefer the look over the ride.
http://www.ebay.com/sch/i.html?_fro...r+shocks.TRS0&_nkw=xj650+rear+shocks&_sacat=0

 

I've got two other pairs of shocks the stock 650 and stock 750 I do like the looks of the shocks on there now kind of sounds more beneficial to change them tho

 

The mufflers are not low enough to scrape, Unless you're on your side.

It's probably scraping either Below your engine, Or your tire scraping on the inside of the fender

 

I do believe this sits lower than stock anyway you slice it my stock exhaust kinda hugged the bottom of the bike and the way it sits right now it's only around 3.5 to 4" off the ground that's with no weight on it when I get on the bike it drops it a little more probably around an inch

Both other sets of shocks I have measure out to 12.5" from the center of the top hole to the center of the bottom hole the shocks I currently have installed are 11" measured the same way

 

Yup, as I said, you're scraping below the engine. It's not the muffler........looking back through the forum now, I see that it appears that the muffler was the assumption, but it's actually the 4-1 union area that is the section in question. I rarely see a 4-1 that hasn't been scraped up and flattened in that area. Maybe thats part of why I don't like 4-1, too........lol

 

Also, thats not the same exhaust as the ones mounted in the previous pictures... at least one shows a chrome system attached. That was the pic I was referring to. This one is indeed low, probably a combination of the suspension drop and the 4 to 1 pipes. They are bulkier underneath the bike where there's the least clearance. Doesn't look like it can get much closer to the frame.

 

The chrome pipes are the stock ones and they are just a little to quiet if the baffle would come out I'd probably still be running with those one