Kawasaki Sportsbike Riders Club - Australia - Online Forum

Wondering if someone could measure their ZRX headers if they have them off the bike. The bit where it enters the cylinder head. Diameter and width of the raised bit,. Thanks! I scored some GPZ900 headers and they may become a turbo manifold if they are the same size.

I've got a spare head sitting at home and could measure up the exhaust ports if that helps

That would be great! Thanks

Righto, so it seems that the maximum OD head pipe you could squeeze in there is 48-49mm (I couldn't tell if there was a slight taper to the casting). From the port face to the base of the exhaust stud is ~21mm (without the gasket), with the stud extending another 22mm beyond that, 7mm of which is unthreaded.

Going by the soot mark it appears that the head pipe, or at least the gasket, has an ID of 38mm with the maximum dimension of the exhaust port being slightly smaller at ~35mm.

Hope that helps

Thanks for that. Much appreciated.

I've got a spare header & pipe at home, courtesy of Strika, so I was able to measure the pipe.
The external diameter is 47mm.
The internal diameter is 38mm.
The width of the "raised bit" is 23mm.
Centres are at 90mm
Pretty much aligns with JB's measurements

The bit that surprised me is that the headers are not even. That is to mean, if you put a straight edge across the 4 header pipes, it sits evenly on the two inner pipes leaving the two outside pipes about 5mm short.

Good to know. Will have to look at 900 headers tomorrow. Cheers!