Header diameter increases

[CROS]

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?

[Hooli]

I can't remember what 14 you have but the K5 onwards headers are larger than the early ones due to being single skinned.

[Eric GSX1400K3]

Try Akrapovic? Mine are stainless and single skinned, no idea about the ID, never measured.

[GSXKING]

My bike was delivered with Yoshi 4-1, titanium headers, not sure of the specifications. They've been on the bike 25 years.

[Irish in Oz]

My 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.

[GSXKING]

My 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 🥵🥵🥵

[Irish in Oz]

My 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 🥵🥵🥵

My 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.

[CROS]

Bike is K7 so that means header is not the issue. Mid pipe maybe? Some more head scratching to do!

[KiwiCol]

What symptoms / issues are you experiencing?

[CROS]

See dyno last week pre and post tuning. Rough at low revs. Loss of smooth power delivery.

[Hooli]

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.

[grog]

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👍

[CROS]

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.

[Hooli]

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.

[gsxbarmy]

Bike 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.