Maintenance & Technical > KX500 Original
Exhaust valve timing..?
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.... :wink:
(H..da CR500 have a different way,look at pic over exhaustport)
As always,just my 2 cent :-D
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
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