XJ900f exhaust header pipes

Can anyone tell me the inside and outer diameters of the header pipes for a XJ900f please? I don't own any callipers or gauges so have tried measuring the circumference with a length of string and applying the 2Pi R rule (I think that's what it is!!) but I'm not getting any sensible answers.

The distance between centres of the ports would also be useful as I am searching for an aftermarket option.

Thanks in advance for your help

 

Circumference = 2pi(r)

So r = C / (2Pi)
Radius (r) is half of diameter, were you doubling your answer when you subbed in circumference?

If you're precise with your string measurement this should work. Might be tough for inside diameter


(unless the exhaust pipes aren't perfectly circular)

Can't tell you the distance between center of the ports unfortunately

 

I measured my Jama aftermarket header pipes and they have an outside diameter of 34 mm.
These pipes have a single wall, so inside diameter is probably 32 or 33 mm.
I forgot to measure port distance, I'll come back to that.

 

As promissed port distances:
#1 - #2 and #3 - #4 : 80 mm
#2 - #3: 120 mm