Exhaust valve timing..?

[John]

I would like to go back to the core of this thread; will there be any benefits in changing the opening time of the exhaust valves?

The equation is slightly more complicated than I originally suspected?

I think I am more or less correct assuming that there are two major parameters involved in the KX5 exhaust; KIPS and pipe. The properties of the pipe are most likely more important that the timing of the exhaust valves. I can tell by looking at Mun?s diagrams.

Let?s draw two different scenarios / approaches;
1. The properties of the pipe are fixed ? exhaust valve timings are variable:
In this case, it would be possible to adjust / optimise the timings of the valve to fit the pipe properties.

2. The exhaust valve timings are fixed - pipe properties are variable:
Typically change the properties of the exhaust pipe until it?s optimised with the timing of the exhaust valve.

It probably safe to assume that the original exhaust pipe and the default exhaust valve opening times are optimised and tuned by Kawasaki..?

I don?t think it?s advisable to attack both approaches at the same time. Maybe choosing a pipe depending on the overall desired effect profile (and get the jetting right), then adjust the spring (exhaust valve timing).

I am not sure I fully understand how much or little the exhaust valve timing impact the characteristics of the engine.


Any thoughts?

//John

[YUNGGUNNAZ]

i am hoping that once pipe and carb combo are chosen(fixed properties)then changing the valve spring,washer or both will show itself on the dyno graph.both in rpm opening and power curve andreaching peak hp. sooner(maybe).i believe it will start the hp. climb sooner.

[doordie]

Guys,
You know that KIPS have one more dimension....
When KIPS closes it makes your PIPE "fatter"!
You have a extra volume in a chamber in barrel to make more low torque.
It foul pipe to think it has more volume at low rpm and less in high rpm range.
"You eat cake and have it still"(sorry about my english,John don?t kill me).
(Kx500 have smaller stock pipes than Cr500)

//doordie

[Spider]

"Have your cake and eat it to"

Your English makes more sense than mine.

Dale

[John]

Doordie,

Don't worry, my English seems to be OK because I use an English spell checker and have lived in this rainy country for 5 eyars now. As long as you are making yourself understood you're fine!

I fail making myself understood on a daily basis - it's called work. Noting to do with the English language though, just the English people  

I hope something good will come out of this thread. I am tooo lazy to participate with any real work, just stupid comments.


//John

[John]

YUNGGUNNAZ,

Have you done any Dyno tests? I just read that you were planning to do some tests. Just asking...

//John

[YUNGGUNNAZ]

john,waiting for new o2 sensor to come in.and hopefully weather won't change on that day.(live in the country 25 mi. away from dyno.)will post as soon as done.i'm going to try to post pic's of two cylinders tomorrow just for discussion.

[gowen]

I've kept out of this thread because I've tried all kinds of kips timings, holding it open, shutting it, trying to space it a little, ect. I've really found very little effect in port timings with the KIPS and feel there is little benefit to doing major modifications to it. Stock is best that I've found and according to MUN it looks like it is pretty tuned off the bat. Now what can go wrong is your powervalves stuck or clogged with spooge or just crap from excess oil. Also your govenor spring worn out. Preventing it from opening or closing correctly. Those are the only issues I've found. I guess it depends on where you are looking for power. I'm questing for a spike, explosion type power while most are looking to smooth it down.. If this is the case (smooth power) I am of no help..

I would like to see HP differences with the pipes and valves. I've done my own little dynos, but that was quite some time ago and am due for another one soon (when it is warm enough to pull the bikes out and fire them up).

[doordie]

I have measured with my tachometer that KIPS start opening about 4800rpm
and half open about 5000 and full open at 5300rpm,just wanna share info.

Most of our engines delivery most torque at 5500 rpm and hp at 6500 rpm and signing of at 7000 rpm.

This make you wonder if you change this ramp to......!!!

//doordie

[redlined_KX500]

I just pulled the cylinder on my 97 K5.  The K.I.P.S. valve on main exhaust port looks like it's not at max height with rod pulled out. Also seems to be excessive slack in the mechanism.

Should the valve be even with cylinder at top?  Not sure if I should try and tighten up mechanism or maybe just de-carbon everything, grind the valve till it's flush and go with it.

[KXcam22]

Redline,
  It's the sides that matter most, not the top.  The side spools open up ports on the side.  You can remove the pins from the main top flap rotate them 90 deg and press them back in. Maker sure to meaure the pin height before you remove them.  Grinding in the top flap is essentially porting and will change the power characteristic giving you more top end. Hope this helps. Cam.

PS one of the best things is to adjust the end stop of the horizontal rod with a small ball bearing. Space it until the side ports are covered. Stock the valves overclose makingone of them actually open again.

[John]

I guess this will be one of the unsolved mysteries of life then - standard is actually OK...

//John

[redlined_KX500]

Thanks for the input. As soon as my top end parts come in I'll adjust the valve and see how it runs. I did notice the side spolls over rotating at closed.  The bike had an odd powerband in the sense it would hit the instant you cracked the throttle, pull for a short time then sign off, in my opinion too early, without much top end pull.

Once my valve is timed proper. Since my engine is already apart, what combo of mods between the reed valves, pipe choice, igniton timing, and head/base gasket combo will turn this bike into a mid-range monster?

Cylinder looked great so I ordered a wiseco piston kit and bearings thus far. Rest of the engine is bone stock. I don't use the low -end very much so that's not a concern.

[doordie]

Just a little explansion about that "overclosing".

Kawasaki did this to solve the problem to start a big 500cc engine,at very low rpm
let compression go by in subexhaust ports and as soon over idle close the port again
to still have enough of compression for low rpm grunt.But when fireing 2 times per row it?s not so good, causes that surgering and backfireing when throttle is closed.

IF you CAN kick it already,get rid of that overclosing....

(H..da CR500 have a different way,look at pic over exhaustport)

As always,just my 2 cent 

[kaw rider]

found this on kawasaki website.

qoute
The stroke of the main Kawasaki Integrated Powervalve System (KIPS) valve has a shorter stroke so that it opens quicker to improve mid-range power