4 in 1 or 4 in 2 exhaust

Basically on a 4-1 system, as one pipe expels exhaust into the collector it creats a vacuum on the next pipe which helps draw the exhaust out faster. Which creats a vacuum on the next pipe, etc. Pretty simple and effective design. 4-2 systems will give slightly better bottom, midrange where as 4-1 give better mid to top end. I just love the look and sound of my old Kerker

Jeff touched on the collector issue. I have two pictures here from both a Vance & Hines, and a Super-Trapp header collector. I'm using the later of the two.


Vance & Hines Collector


Super-Trapp Collector

You want a "merged" collector for best flow, but ground clearance in corners under our bikes is probably the limiting factor for why most are like the pictures above. Cleaning up the welds a little would improve the flow, and seeing on how mine's off right now, I'll be looking into that area. Will I notice the difference? Nope, but it's something I want to do.

I don't know how many of you noticed it, but there's a trend in the car world toward smaller, higher velocity header pipes.

The higher the state of tune of the engine, the more important pipe tuning becomes.

larrycavan wrote:

I don't know how many of you noticed it, but there's a trend in the car world toward smaller, higher velocity header pipes.

The higher the state of tune of the engine, the more important pipe tuning becomes.

yep;)

larrycavan wrote:

I don't know how many of you noticed it, but there's a trend in the car world toward smaller, higher velocity header pipes.

The higher the state of tune of the engine, the more important pipe tuning becomes.

Larry I need some exhaust/intake port modeling.

Peace&Love:blink: , Darren

kyradawg wrote:

larrycavan wrote:

I don't know how many of you noticed it, but there's a trend in the car world toward smaller, higher velocity header pipes.

The higher the state of tune of the engine, the more important pipe tuning becomes.

Larry I need some exhaust/intake port modeling.

Peace&Love:blink: , Darren

As in a port mold?

dutchz wrote:

Got a set of 4-2 hooker pipes with a crossover on mine, similar to the milkman's Jardine but the headers cross differently. Great mid range, looks good and sounds even better...

Those are nice looking pipes... I was running a MAC 4-1 that I really worked hard on tuning the bike to... then just for kicks one day, I cut off the stock pipes right in front of the baffle, bolted them on and was suprised at how much the power seemed to be spread out... the power was a lot broader and I liked the look a little better for my cafe project.

They work very well. I've put in the baffles from the old set that came on the bike, the straight-thru tubes are a little larger diameter than the ones on the NOS set I found. No packing tho :whistle:
These pipes sound bitchin... completely different from a 4-1

a bit of a side note here, how does running a 4-1 without the megaphone at all compare to running the same 4-1 with the megaphone with no baffle? both are wide open, but one is longer and has the funnel shape....
Scott

Seems to me that having the megaphone on would create a bit more of a vaccum on the other pipes creating a better scavenging affect, and being a megaphone wouldn't it make it a little louder?
Just my thoughts.
Les

if the megephone started back a ways from the collector would it still make extra vaccum or just if it started right at the collector?

This is getting very interesting!! I did have a home build 4 into one with a header of approx 20 cm long and diameter of 10cm. No bafle and big diameter pipes. It pulled very hard on a standard KZ900 from 8000 to 10.000 but it was very loud and fuel consumption was poor. I replaced it for an original one, gave more low and mid and no hard pulling engine above 9000rpm. Now I do have a shitty marshall, stock diameter pipes and very restrictive above 7000rpm. I do have the same damper on my kz650... I can't get it tuned propely with pods.
Anyway I was making plans to use the stock pipes making a two into two system. So first qeustion. Do you have to pair 1-4 and 2-3?? easier is 1-2 and 3-4 or do you get a harley effect 0 and 180 degrees fire...

I would make an oval header with the surface of the 2 incoming pipes. Headerlenght approx 20cm going fluently in a megaphone/trumpet minimal damped muffler, what do you think (especially Larry?)

Martijn