Newby with Lots of Questions - Kawasaki head

[Ozonkiller]

I recently built a flow bench using Flow Performance stuff (Good stuff by the way and John was great to deal with).

This all came about as I am building a Kawasaki motor and decided that all of my years of porting by guess and by gosh needed to be verified. I'm glad to say that as far as I can tell I haven't been making any glaring mistakes but I do have a bunch of questions now.

First is velocities. I've got velocities well into the 300's everywhere. I'm reading 350 or so in front of the divider and when I get down past the divider about 1/2" they go waaay up sometimes to the 400's!! This is of course with the throttle bodies not attached. The CFM is 220 @.400 lift (Not bad for a stock port) If I put a string in the port it starts out straight but as I go into either of the smaller ports it goes ape and spins like crazy. Am I correct in my thinking that I should (can) go bigger to slow things down while bringing up the CFM

Next, while probing around with the velocity probe, I find that there is an area in each of the runners that if i disturb it the noise goes down? I'm not sure what to make of that. In the left runner it's at about 4 to 5 o'clock and in the right one, it's at about 7 to 8.

There is a dip in the floor of the runner right in front of the short radius. With no other port work, I filled that dip in w/ modeling clay and raised the floor a bit to try and improve the short radius. Bang!! 220 to 228 cfm, just like that.

My question is, what's a good epoxy to use on an aluminum head. Are there any special tricks that will help? I'll slit my wrists if the epoxy comes loose and hangs a valve open. A lot can happen at 11,000 RPM. I looked around on the forum but I was never sure if they were doing iron or aluminum heads, if that makes a difference

Last (for now), there's a small void in the roof of the port where the valve guide comes thru'. Do you think that's worth messing with. I guess I could fill it with clay and answer that question myself. I'll let ya' know.

Thanks for you time and I look forward to hearing from yous guys

Tom

[hdwgfx]

Great questions!

search sppeedtalk.com, google this -->


csa site:speedtalk.com

port velocity site:speedtalk.com

[maxracesoftware]

If I put a string in the port it starts out straight but as I go into either of the smaller ports it goes ape and spins like crazy. Am I correct in my thinking that I should (can) go bigger to slow things down while bringing up the CFM


don't always go bigger...instead find the "Best Shape"
that gives you Flow Stability,
then if the FPS Speeds are too high,
tweak that Shape to slow the FPS down
always in conjunction with Flow Stability !

its not so much the hi fps speeds the Problem,
its the Shape that can't handle those higher fps speeds.

[larrycavan]

Adding to LM's advice....

Check both runners FPS at the divider. Probably not equal. I see a lot of that. Air is splitting at the divider, shapes there and prior to there will determine how much air goes in which direction.

First glance ports appear to be straight. Often they're not. Generally one runner get's favored for flow at the divider. Sometimes if you look carefully, the outside wall on one side or the other will need to be worked to aim the air into the split a bit better.

Just prior to the divider a string test, fed down the middle, will generally show the string going crazy as it nears the divider. Sometimes side to side. Sometimes spinning wildly. On some heads, I've let the string feed down one side and held it at a point where the end is just past the divider....only to watch it flip out of that runner and dive down the other, leaving the string bent over the center dividing wall. Port can get real noisey with the string in there at 28" test pressure.

On some heads, I have calmed that down with a combination of shortening the divider and removing the leading sections that form a slightly rounded wedge shape where the finally meet up right at the dividing wall between the two runners, right near the SSR. How you fix it depends on how much bias is cast into the port from the factory.

IMO - focus on fixing that turbulence problem and don't focus on big CFM gains.

Spec the motor out and you'll probably see it flows more than adequate air for the RPM you're after. Calming down that disrupted flow pattern will probably buy you more in real world acceleration than just going after another 20CFM and not correcting that situation.

Is this a down or side draft 4V Kawi?

[Ozonkiller]

It's a Kawasaki ZX14. It would be considered a down draft.

Your descriptions of what happens befor and at the dividers is spot on. The center two ports are a straight and relatively even shot at both valves, whereas the outer ports, the outboard most valves are "around a slight bend". With some very subtle work on the outer walls, I have been able to gradually bring up the cfm and velocity to where they are very close to being even.

I'm going to try and post some pictures. It may be a couple of days as I'm in the A/C and refrigeration business by trade and it's starting to get warm in Phoenix.

Stock this thing makes great power (189.769mph at The Texas Mile and 9.95@142 mph in the 1/4) so obviously they can't be too bad. I'm just trying to make what the engineers had in mind vs. what gets lost in mass production... and maybe a little more.

My wife just shakes her head, smiles and says, "POS won't do 190." ;:):

Thanks again for the input. I look forward to more!!!!!!!!

[larrycavan]

How much do the TBs kill the flow?

You have an advantage of being able to probe with the TBs installed. Use it to your benefit.

No idea why they put that funky dip in the floor in front of the SSR. I don't like the looks of the floor in those ports in general. Obviously it works. The bike is making lots of power. So much they hobbled it with computer controlled secondary TBs and gear specific ignition curves.....don't want people tipping over backwards in second gear!....

Did you yank your secondary TB's yet?

Glad you posted here! Interesting to see your results....

As long as your wife encourages you like that.....it will do 200 if you get things right. Brock did it with a stock head

Here's an article for you that was on dragbike for a short while. Also, there's some info over on zx14.org and a bit on speedtalk about the 14 head. A guy in Mass. digitized the ports and posted some data.



Edited By larrycavan on 1208398709