2024 6 into 1 options?

[CBX-tras]

MAC means Make-Another-Choice.

[FalldownPhil]

The Patriot pipe is actually a MotoGPwerks it appears.

[512tr]

There just aren't any. DG is junk, Delkevic not much better. Unless you want to spend a fortune on a basically custom-build one. Your best hope is to find an old D&D or Bassani. They are around.

Dave

Dave, you say DG is junk, what’s the bad experience with the DG headers?
The reason I’m asking is that I have this unused 6:1 lying on the shelf, bought from Tim’s a long time ago, advertised as Kerker 6:1 Competition Exhaust.
I assume this is DG headers with a Kerker can.

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[daves79x]

You are correct - that is a DG with a Kerker can. Lots written about the shortcomings of the DG. Biggest is the huge flat spot between 5-6K, that you can never jet completely out.

The MACs are just not a very good quality pipe and they sound kind of tinny.

I'd get one of the couple of stock reproductions and be happier.

Dave

[SanDogDewey]

That Kerker pipe brings back memories of the 400F, with a couple additions!

[Larry Zimmer]

As Dave said about the flat spot. Same thing with a 4-banger and 4-1. The -into 1 pipes are intended for top end. Generally, need to get above 6k. Better yet, 7k and above. Definitely not good for roll-on throttle. (Ask me how I know.) BUT, if it's top end you want, do it. And, jet for it.

[512tr]

As I have the complete DG/Kerker system, and just out of curiosity I will put it on this summer and see how it performs with my engine.

I will weld in an O2 sensor bung and monitor the AFR (as I do with my current exhaust) and see what’s going on.


My current experimental exhaust is an old Predator 6:1, modified to 6:1:2, which works very well.

[bobcat]

The more I read and see this stuff the more desperate I feel about
being able to get up out of this bed and get to work on my 6-2-1 project.
I got as far as the collector* before I wound up in the hospital (about 4 yrs. ago).
All I need to finish the header tubes is get out the R&D platform mockup motor
and figure out how to route them to maintain the 3 pair staggered lengths.
The Rest of the pipe, the megaphone, will have to be done with the header/collector
assy. on one of my assembled bikes for the routing and mounting points.
Then figure out if it can be made affordable. Meanwhile it's just daily panic attacks.

*see pg. 1

[Rick Pope]

What's being forgotten, and Bob has mentioned it previously, is that head pipe diameter plays a big part in tuning and whether flat spots occur in the rpm range. To this non-engineer, the big head pipes are what makes the D-G perform poorly except at higher revs.

I have an old Hooker header on my CB750/836, and it has no flat spot, pulls cleanly from idle to deep into the red zone. It also has rather slender head pipes, compared to the RC and other popular exhausts of the day.

[CBX-tras]

If there is any question on pipe diameter, just remove one of the center pipes from either side of the stock exhaust.
You'll find that Honda made these tubes, double wall. A tube within a tube.
Measure the ID of the inner tube and THAT'S the size that you should be using. Additionally, the tube is pinched even smaller as in enters the collector under the motor, creating more back pressure.
Without the proper back pressure, these motors fall flat on their face.

Some modern sport bikes have an electronically or cable-controlled butterfly type of restrictor in the exhaust system that doesn't open fully until WOT.

[512tr]

What is the stock header tube ID?

I checked my headers, ID at head side is 29mm (welded in short pipe w/flange) and the rest ID 32mm.
OD is 35mm

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[bobcat]

I was writing about some observations and ideas but it was getting too lengthy
so I scrapped it but looking at the design of the above system I can see all kinds
of reasons why it would kill power at any rpm range. (sorry to be so harsh).

The only problem with the ID of the double wall stock/OEM sys. is that small of
a single wall header tube would look kinda' silly. Ideally I would use the OEM
double wall about halfway down the tube, then single wall outer tube only the
rest of the way to the collector. Something I would like to experiment with bending
given the opportunity. Start with a full length OD tube with a half length inner wall.
If the bend is complete before the end of the short inner wall it should be doable or
at least worth the try. This would give you an internal "step out" to a larger ID leaving
the cosmetic OD of the full length of the tube uninterrupted. You usually see this done
by welding the first half of the tube to a larger DIA second half*, kinda' ugly.

[Jeff Bennetts]

You’re not being too harsh Bob, I have no idea why the exhaust has been so popular over the years. It’s been known that this pipe has a terrible mid range flat spot for the last 20 yrs and verified through Dyno testing, no matter what canister is on the end of this system.

[512tr]

As mentioned, I bought this 20 years ago and have been lying on the shelf unused since then. I have read about that “flat spot” problem on many occasions, so there is a reason (among others) that it has been collecting dust for 20 years.

I will expect it is running lean in the “flat spot” area due to less back pressure and different exhaust flow characteristics compare to the stock exhaust.

Bob, as you have done a lot of research and have unique plans for an exhaust system with different ID pipes, you probably know the stock double wall tube ID ?

[daves79x]

If you look at probably the best 6-1 ever made, the D&D, it has noticeably smaller-diameter head pipes.

Dave