intake throat and valve size

So you want a bigger intake valve. Where does the increased flow come from?

Is the inside of the valve seat made larger all the way through? Or

is the valve side only modified to blend to the existing throat taper and dia. ?

If I turn down my valves smaller, opened the throats cut in some angles, did

I just ruin my head or am I going to go faster?

:woohoo: Are the throats on the j heads larger diam?

Dont want too many questions, this should be enough for now.

I'm talking getting hp out of these and how much you gain with the bigger valve.

I gotta have a good head to put a good carb on, I have to heads that are done

Identical.

nads.com wrote: So you want a bigger intake valve. Where does the increased flow come from?

Is the inside of the valve seat made larger all the way through? Or

is the valve side only modified to blend to the existing throat taper and dia. ?

If I turn down my valves smaller, opened the throats cut in some angles, did

I just ruin my head or am I going to go faster?

:woohoo: Are the throats on the j heads larger diam?

Dont want too many questions, this should be enough for now.

I'm talking getting hp out of these and how much you gain with the bigger valve.

I gotta have a good head to put a good carb on, I have to heads that are done

Identical.

Increase the bowl and cut the hole,
Find the Devil and sell your sole,
R6's are quick but R1's are faster
If you do the head wrong they'll both be your master

L8ter Dude

GoNads...you got 'em or you don't :woohoo:




www.cavanaughracing.com/kzdata.html

sounds like you are porting your heads right?

So how is this done, this machining for the bigger valve :blink:
This is a serious question :laugh: A scary one... :huh: If you know how this is done and
speak on it, you will be exected instantly, so go ahead lay it out...

nads.com wrote: So how is this done, this machining for the bigger valve :blink:
This is a serious question :laugh: A scary one... :huh: If you know how this is done and
speak on it, you will be exected instantly, so go ahead lay it out...

Discussed that again, briefly, in this thread.

www.kzrider.com/forum/21-tools/556328-wh...stones-for-this]Over Size Valve Install

Head in the pic is getting 38mm intakes. It's a 1075 motor with Web 109 Grind Cams, APE buckets & Valve Guides, Kibble White Springs, OEM 650 retainers, top secret valve seals.

Gut feeling is that increasing valve head diameter size would increase tendency to develop crack in head between the valves. At least with respect to long term street riding durability.

www.kzrider.com/forum/2-engine/558556-head-crack#558610




Good Fortune!

Did I see a question earlier about that small crack between plug hole and valve seat?
I know that is common. I have used stock heads like this before.
I have a nice ported Mark II smog head.
But I see that tiny crack at the plug hole. You need a magnifying glass to see it.
I would hate to sell it this way.

I used 37.5mm intakes and 31mm exhausts in stock seats before.

z1kzonly wrote: Did I see a question earlier about that small crack between plug hole and valve seat?....

Click > www.kzrider.com/forum/2-engine/558556-head-crack#558610

Good Fortune!

Never saw one crack from installing oversize valves. There's more seat material in those heads than any other Kawasaki head I've ever seen. Besides, it's not the seat that cracks, it's the aluminum.

Your right Larry, it is the aluminum of course. The seats don't crack.
the type was wrong. I was not takling about same head.

I was just talking in my brain and typing to myself.

I have an old Z1 Turbo head that has Manley oversize valves and old school R C Eng.
Valve retainers that are anodized "Teal" color? They are aluminum, I think?
I am not lucky enough to have them Titanium.
This head was done by "Jerry Branch!" from Branch Flowmetrics! How old is this?
They are going to ebay, 8 stainless valves, springs, retainers and keepers (which are rectangular)
37.5mm intakes and 31mm exhaust valves. They are swirl polished.

I have another smog head with the crack, that head is complete but I see that damn crack!.
I don't have much time to type so, I'll post a pic later.

z1kzonly wrote: Your right Larry, it is the aluminum of course. The seats don't crack.
the type was wrong. I was not takling about same head.

I was just talking in my brain and typing to myself.

I have an old Z1 Turbo head that has Manley oversize valves and old school R C Eng.
Valve retainers that are anodized "Teal" color? They are aluminum, I think?
I am not lucky enough to have them Titanium.
This head was done by "Jerry Branch!" from Branch Flowmetrics! How old is this?
They are going to ebay, 8 stainless valves, springs, retainers and keepers (which are rectangular)
37.5mm intakes and 31mm exhaust valves. They are swirl polished.

I have another smog head with the crack, that head is complete but I see that damn crack!.
I don't have much time to type so, I'll post a pic later.

I have some of those retainers. Ti retainers don't buy anything on a street bike. They just cost a lot of money. OEM SOB are the way to go there IMO. The late GPz retainers will give you an extra .100" of coil bind clearance over the old 650 stuff. Sorry for misunderstanding on the crack deal. I was replying to the previous post from Patton.

Thanks for the update Larry. I know these were on a Z1 street bike turbo from the early Z1 days.
This thing was never raced. It was built for show and street light to light on the street!
This was sitting along time as in double digit years.
Here is a picture of them, and the show quality stainless Manley valves :laugh:
Sorry, I forgot to downsize the picture.
They are on ebay tonight.