Born Dead 2 wrote:loudhvx wrote:
You have to remember Cylinders 1 and 4 are opposed in timing, and 2 and 3 are opposed in timing (by 360 degrees). Those are the pairs that should be combined into a pipe. 1 with 4 and 2 with 3.
If you combine 1 with 2 and 3 with 4, the pulses are unevenly timed, so one cylinder's pulse will affect the breathing in the other cylinder in an unequal way. You may even have to alter the jetting like the way they are in uneven twins (like the Honda 350 or various v twins).
(KZ 400 and 750 twins are 360 twins so they are evenly timed.)
To get around that problem, you install a crossover pipe to even things out, or combine all four into one at the same point.
Yes this is true, and when I built this exhaust I based it off my 750 which has the xover pipe. Reason I didn't do the Xover origionally was the exhaust Z1 sells is 1 and 2 into the left side and 3 and 4 into the right side. So I based it off that system. So are you saying that when you buy an exhaust from Z1, it's not going to run right since there is no Xover pipe?
Well, I'm no expert by any stretch, so I can't say for sure it won't run right. I don't think it will affect things to the point that it will stumble or bog, but it just won't be optimum.
I'm just basing this on experience and from what I've read. (I've built a few muffler systems for various bikes, I have a thread going in the engine section called "I'm Baffled".)
In my experience, the lack of a srossover is not a significant problem, but it's not perfect either.
If you notice, in engines with uneven firing intervals (like harleys, CB350, CB450, some Ducatis) they keep the exhaust as one pipe per cylinder. But on twins like the KZ400, where the intervals are evenly spaced at 360 degrees, they actually had a factory 2 into one setup (The KZ400 S model, I believe). It weighed less and was cheaper, but worked well even though the layout was funky with a 90 degree T connection.
But Like I said, it's probably not that big a deal unless you are trying to get maximum performance.
