GPZ750/810 racer running....

nice, i bet just the 7mm diference in bore creates nice band all around.

that said, i am going to stick with the big 34mm inlet of the gpz head

These old Kawasaki heads have no short side height. Always a challenge to get the air to distribute around the valve.

If you'd put a pitot in there though, you'd see the floor is faster than the roof.

Exhaust ports are sometimes dead for half the height above the floor. Cheat the throat to the long side when you punch it.

larrycavan wrote:

These old Kawasaki heads have no short side height. Always a challenge to get the air to distribute around the valve.

If you'd put a pitot in there though, you'd see the floor is faster than the roof.

Exhaust ports are sometimes dead for half the height above the floor. Cheat the throat to the long side when you punch it.

Was that English? :blush: The pictures are pretty, though...

that's excellent english actually...

Speed fastest at floor? intersting though not really surprising considering the strong banana shape the 750 ports have. Havent done rubber casting of the port yet but quite easy to see that the roof is pretty flat while the floor curves up before going down, essentially a wing's airfoil.

in another forum someone posted an interesting section of a fast four valve suzook and looks quite the same, nevertheless tuner added some 7mm of epoxy to the floor.pic is afte this post, havent discoverd how to attach more than one pic per post yet...

Coming to Kawi's after working on small sohc's, whats a bit shocking is that the length of the port doesnt really let you vary much the angle of approach. in my sohc, i managed to build a 10 deg downdraft angle (blue lines) but to do so in a kawi, you'd need to saw most of the port off.... has anybody done this before?

imdb record setting suzi head

www.flowbenchtech.com/porting/CRH/sps.htm

Here's another Suzuki

forgot to say, nice shot larry! would be nice to see the side view too if its not a secret

been crnaking quite a bit in the garage, cycle side is 90% there, so giving some attention agian to the motor.

First step, some port castings, just to really "see" what's going on in there

these are cyls 3 & 4, and the most baffling for me is the strong bulge outwards just after the valve guide, specially in #4

i can see that kawi engineers where trying to aim the flow more symetrically but somehow it looks wrong, but what do i know

just in context

BTW, the "bathtubing" of the heads to get a squish band around is done too, will post a close up later

here are the sections measured, the graph shows how it changes along the tract

turboguzzi wrote:

just in context

BTW, the "bathtubing" of the heads to get a squish band around is done too, will post a close up later

Those heads don't have a lot of meat on in the roof on the long side of the bowls like the old 900/1000's do. At least the 82's didn't anyway. The 83's might be better. Be careful if you cut it significantly deeper on each side of the guide or you'll be getting out the epoxy

If you look at your chart photo, the danger zone is between 2 & 3 for grinding through.

They're not paper thin but they're not overly beefy either.

Punch the throats to 90% if you want and stay under valve diameter in the bowls. Valves should be 35mm if IIRC. Probably pushing around 70 @10 stock.

thanks for the tips larry

so not much to do about the strong "S" line in 1 & 4?

my concern is that flow cant really stick to the outside wall (the right wall in cyl 4 for instance) so essentially the effective section gets chocked there and most of the flow conitnues to the pocket space left of the valve guide

The other thing i was considering was raising the floor a bit around points 4-5 for some venturi effect at the ssr.

Stock valve size in the GPZ is 34mm BTW, both port entry and throat are 29mm internal diameter = 660 sq-mm