Hello
Has anyone had experience of accessing wider diameter headers? I have found one stainless provider Black Widow whose single skin stainless 304 pipes are 39mm internal diameter. Any others?
I can't remember what 14 you have but the K5 onwards headers are larger than the early ones due to being single skinned.
Try Akrapovic? Mine are stainless and single skinned, no idea about the ID, never measured.
My bike was delivered with Yoshi 4-1, titanium headers, not sure of the specifications. They've been on the bike 25 years.
Quote from: GSXKING on Monday, 01 June 2026, 08:16 PMMy bike was delivered with Yoshi 4-1, titanium headers, not sure of the specifications. They've been on the bike 25 years.
Must be why it's so fast.
Quote from: Irish in Oz on Tuesday, 02 June 2026, 07:22 AMQuote from: GSXKING on Monday, 01 June 2026, 08:16 PMMy bike was delivered with Yoshi 4-1, titanium headers, not sure of the specifications. They've been on the bike 25 years.
Must be why it's so fast.
Not as fast as you 🥵🥵🥵
Quote from: GSXKING on Tuesday, 02 June 2026, 07:31 AMQuote from: Irish in Oz on Tuesday, 02 June 2026, 07:22 AMQuote from: GSXKING on Monday, 01 June 2026, 08:16 PMMy bike was delivered with Yoshi 4-1, titanium headers, not sure of the specifications. They've been on the bike 25 years.
Must be why it's so fast.
Not as fast as you 🥵🥵🥵
Quote from: GSXKING on Tuesday, 02 June 2026, 07:31 AMQuote from: Irish in Oz on Tuesday, 02 June 2026, 07:22 AMQuote from: GSXKING on Monday, 01 June 2026, 08:16 PMMy bike was delivered with Yoshi 4-1, titanium headers, not sure of the specifications. They've been on the bike 25 years.
Must be why it's so fast.
Not as fast as you 🥵🥵🥵
And I have a stock K7 with a bazooka.
Bike is K7 so that means header is not the issue. Mid pipe maybe? Some more head scratching to do!
What symptoms / issues are you experiencing?
See dyno last week pre and post tuning. Rough at low revs. Loss of smooth power delivery.
Pre & Post tuning.jpeg
Is it definitely revs related?
I know what your graph shows but I can't remember if they do those runs by slowly opening the throttle or pinning it from the start. I ask as you can get dodgy sections on the TPS & the same amount of throttle causes rough running at any revs.
3.5k rpm is about where it stops using the MAP sensor & the secondary throttles open, so that's a few other bits to poke at too.
Need to get that fuelling sorted. Dont want a 14 with no low down grunt, most important part. Doesnt matter what you do, top end wont match the sports bikes, just a good feel for you👍
Thanks, Hooli
Very useful. May sit on this a while and ride the bike. Been a year so keen to get my hands on it.
Oh I forgot one other thing, there's normally a dip/flat spot around 3.5k as the timing is retarded there so the bikes passed the drive by noise test in type approval. It shouldn't cover as big a range as your rough bit, but it does mean it'll never look a perfect curve. You can't feel it as you ride though.
Quote from: CROS on Tuesday, 02 June 2026, 04:26 PMBike is K7 so that means header is not the issue. Mid pipe maybe? Some more head scratching to do!
If you have the optional Yoshi can fitted then the standard link pipe between the headers and the can has a baffle in it which is virtually impossible to remove without destroying the link pipe. Years ago, when the K7 first came out, one of the members got a batch of straight thru link pipes made which helped the mid-range.
If you get an aftermarket can with link pipe, that also solves the problem.
Can I ask what modifications you have done please? I have a better looking power curve but the numbers are way down on yours, although she pulls like a train. My bike was in standard trim other than a pair of Delkevic cans
https://www.youtube.com/watch?v=eFSN593UieE
Quote from: Hooli on Monday, 01 June 2026, 06:16 PMI can't remember what 14 you have but the K5 onwards headers are larger than the early ones due to being single skinned.
Totally wrong Hooli. Both chrome and stainless headers are double skin. Stainless outer is slightly bigger but the internals are the same.
That's never been the person perceived wisdom on here, but if you've got anything to show that I'm happy to be corrected.
I've never had standard late downpipes off myself so just going on what others have always said over the years.
I don't know the diameters, but I do recall Pete doing some work on the exhausts & had pic's of them off and he was measuring the internals from memory. So if he says they're the same, my coin is on Snapey with this one.
Search "header pipes for k2" and you'll find that discussion, from 2019. I don't know how to link to it, or copy from it.
Admin added
On behalf of
@Pommeroy this is the link https://gsx1400owners.org/forum/index.php?topic=4448.msg57987#msg57987
Quote from: Hooli on Thursday, 04 June 2026, 03:28 AMOh I forgot one other thing, there's normally a dip/flat spot around 3.5k as the timing is retarded there so the bikes passed the drive by noise test in type approval. It shouldn't cover as big a range as your rough bit, but it does mean it'll never look a perfect curve. You can't feel it as you ride though.
The bike is fitted with a TRE (timing retard eliminator - tells CPU that bike is in 6th gear all the time so no rev limit) so this should not occur
TRE's are a complete and utter waste and generally the majority do nothing at all. In over 19 years of owning and working on 14's and being on 2 GSX1400 forums (this one as admin and on the previous GSX1400.org), I've never yet seen a good word said about them, nor anything that claimed they had any real effect - in fact some TRE's in the past actually caused wiring issues and overheated, catching fire.
Personally I'd junk the TRE- if you want to change your timing, do the timing plate mod, much safer and works.
https://gsx1400owners.org/forum/index.php?topic=144.0
Sorry Dave, my Healtech been fitted 14 yrs, never a prob. Gear indicator included, i like that also. If i turn it off, much rougher around town.I dont like backing plate mod as 5&6 gears then go another 4 degrees, they are not retarded to start with, too much imo. All i have to say. :)
Quote from: grog on Friday, 12 June 2026, 06:27 PMSorry Dave, my Healtech been fitted 14 yrs, never a prob. Gear indicator included, i like that also. If i turn it off, much rougher around town.I dont like backing plate mod as 5&6 gears then go another 4 degrees, they are not retarded to start with, too much imo. All i have to say. :)
Healtech are good
@grog, and in their case the TRE element does work - as I said in my previous post, its the majority that don't. I never had the TRE element of my Healtech gear indicator engaged as I used the had a timing mod done instead
Quote from: Will14 on Thursday, 04 June 2026, 07:07 AMCan I ask what modifications you have done please? I have a better-looking power curve but the numbers are way down on yours, although she pulls like a train. My bike was in standard trim other than a pair of Delkevic cans
https://www.youtube.com/watch?v=eFSN593UieE
Hi, engine has had Yoshi ST1 high lift cams and has been ported and flowed (a few other tricks from race team mechanic). This accounts for most of the difference plus tuning in to Power Commander 6. I have just posted a couple of pics. I will likely go to a new header system though.
Quote from: Hooli on Saturday, 06 June 2026, 11:14 PMThat's never been the person perceived wisdom on here, but if you've got anything to show that I'm happy to be corrected.
I've never had standard late downpipes off myself so just going on what others have always said over the years.
This is from a K5 Hooli. Stainless outside, stainless inside.(https://live.staticflickr.com/65535/55335282444_950e67778e_w.jpg)(https://flic.kr/p/2siMua1)
Quote from: Snapey on Monday, 15 June 2026, 07:58 AMQuote from: Hooli on Saturday, 06 June 2026, 11:14 PMThat's never been the person perceived wisdom on here, but if you've got anything to show that I'm happy to be corrected.
I've never had standard late downpipes off myself so just going on what others have always said over the years.
This is from a K5 Hooli. Stainless outside, stainless inside.(https://live.staticflickr.com/65535/55335282444_950e67778e_w.jpg)(https://flic.kr/p/2siMua1)
Thanks, that's a lot bigger gap between the skins than I would have expected too,
Quote from: Hooli on Monday, 15 June 2026, 08:44 AMThanks, that's a lot bigger gap between the skins than I would have expected too,
What's got me stuffed is how they bend the two tubes.
Hydro forming? Nope, wrong for headers. apparently it's done like this:
bending.jpg
Black Widow headers are single skin stainless, inside 39mm, guessing stockers in Snapey photo prob 10 mm less. I like exhausts to be open as possible. Anyone used them? That must give a better flow. $350 plus freight, gaskets, clamps and collector box. Pretty good buying I reckon.
I've got some Black Widow headers but managed to get hold of some original chrome ones for my K2, the reason being purely for aesthetics the aftermarket pipes discoloured very quickly and looked tat, can't say I noticed any difference in performance, but I am an old fart and don't push on too hard these days...
T250, no good to me if they discolour, I'll forget about that idea. Thanks
Quote from: grog on Tuesday, 16 June 2026, 10:17 AMT250, no good to me if they discolour, I'll forget about that idea. Thanks
Having no inner pipe
@grog they will "bronze" almost immediately, probably most of the way down the header as well.