Porting the Z1 by Joe Hooper

Hi Folks,
Joe Hooper of Pit Stop Performance has written a great article on porting a KZ.
You can peruse it here:
www.kzrider.com/articles/283-porting-the...0-kz1000-and-zx1100a

Enjoy
Bill/KZQ

Wow!  A very comprehensive guide.  Doesn't get any better as a reference source.  A big thanks to Joe H. for writing it and to Bill/KZQ for highlighting it.

Mike

Fantasic read and information. Thank you for sharing your secrets Joe!

I deleted several posts having to do with accessing the article. Not sure why the permissions didn't work properly. But it's fixed now.
Sorry
Bill/KZQ

That´s a great piece of knowledge!
but I think I have a understanding Problem of the "C" Value.
It is described as: "DO not touch blue Of seat, measure below seat use an old valve turned to XX". Valve Should go in until it touches the Valve guide."
So we are talking about a round Area we can access through the seat via a "feeler Valve".

Using the Values for a KZ 1000R Stage I Value for "C" 1.387"= 35,2298 mm with a std. Valve of 37 mm this would mean that we have Throat of 95%, which seems to be huge to me.

I am convinced that the values given are correct, so could anybody explain where I turned wrong in my thought?
 

My understanding is that 90% of the valve diameter is the sweet spot for the throat 

Exactly, but in that case we would not be able to get our "feeler valve" in there.
So the numbers given for "C" have to be ment somehow differently.

The "C" values quoted on the chart are based on the largest valves that can be used on the stock seats not the stock size valves.
The "C" value will have to be adjusted to suit the valve sizes you are using and the percentage figure you require.
 

It does seem strange, when I did my 1000J I used the 90% figure given by zed1015 which is 33.3mm for the throat. Even at this you are cutting into the steel seat so at 35mm you would be into the valve seating area with very little seat left. (37mm valve with a 1.0mm sealing area would be 35mm if the contact area was on the very outside of the valve)

zed1015 wrote:

The "C" values quoted on the chart are based on the largest valves that can be used on the stock seats not the stock size valves.
The "C" value will have to be adjusted to suit the valve sizes you are using and the percentage figure you require.


 

that does not seem to be correct since the "C" value is given for each stage incl. the Stock values


A Measurement behind the seat bigger than the Throat is reasonable but this does not work withe the "measurement valve".
The only Way this Could work, is to cut the valve, first to the according diameter and than cut the Valve, so it looks more a less like a "T" so you can angle it into the valve seat.
But the description of the "to dos" is quite clear and does not describe such a process.