KX Riders
Maintenance & Technical => KX250 / KX125 => Topic started by: needsatopend on August 14, 2015, 01:21:02 PM
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'01 kx250
When the short tooth on both subvalves are lined up with the mark on the main rod, my subvalves won't fully open
Here in the correct timing, the short tooth is aligned with the line on the rod mark
(http://i.imgur.com/5l5mP93.jpg?1)
And when I look down the exhaust, with KIPS at fully open position, the valves are barely half way open
(http://i.imgur.com/im3B2r9.jpg)
Now if I rotate both subalves out by one notch, it seems like it would be the correct way they should go..
Here short tooth is to the left of the rod mark on one side. Same done to the other
(http://i.imgur.com/GqeIzQI.jpg?1)
And the valve is more fully open. flat surface of the flash i flush and makes a fully open port
(http://i.imgur.com/dG81alr.jpg)
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Check the timing on your Main / Center valve, if it is not timed correctly it will prevent the Side / Barrel valves to not fully open. Hope this helps.
DoldGuy
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The center flapper valve is completely closed when aligning the 2 side valves and idle gear
It works perfectly, just the two side valves needed to be rotated by one tooth to line up
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The center flapper valve is completely closed when aligning the 2 side valves and idle gear
It works perfectly, just the two side valves needed to be rotated by one tooth to line up
I understand it is fully closed, but, it also needs to be correctly timed, otherwise, it will prevent the side valves from fully opening.
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Nope I'm confident I have the main valve lined up; at the upper side cover, the dot on the gear tooth lines with the mark on the smaller rod that runs off one of the side valves...I did that first
From the manual(after doing center valve installation):
-Turn cylinder upside down
-Push main valve rod as far as it will go
-Insert the exhaust valves in the cylinder. The right exhaust valve [A] is smaller, etc tec
-The punch marks on the valve pinions should align with the grooves [C] on the rod
.......
Well in that "correct" orientation, the side valves are not fully open. Unless I shift them one notch...one goes clockwise and the other counter-clockwise
Try these videos:
This is the "correct" assembly with the marks aligned----> http://gfycat.com/LegalDesertedClumber notice the side valves don't fully open
And when I shift them one tooth out from the alignment mark-----> http://gfycat.com/DearWellmadeAmericancrocodile
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Needsatopend,
A simple confirmation that you do (or don't) have the main valve timed correctly....
Turn the cylinder upside down, remove the center valve and pinion rod & gear. Now only install the side / barrel valves with their marks / dots aligned, pull the rod out & back in to confirm they open & close fully. The rod will be stopped from the bushing that holds the power valve seal on the lower right of the cylinder (lower right in the upright position). I think once you "See" this opening / closing of the side valves it will explain more than I ever could behind a keyboard. Again, hope this points you in the right direction.
DoldGuy
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There is only 1 way to time the flapper valve, and it's on the left side of the motor(upright) with the timing dot on the upper rod gear and alignment mark on the smaller rod
Ok we I lldisconnected the flapper gear upper horizontal shaft, and small rack rod so only the main rack rod and side valves / idler remained....
The side valves do fully open and close when aligned with the timing marks....but as soon as I reinstall the the upper mechanisms for the center / flapper valve, the opening and closing is limited by the flapper (the main part of the center valve that pulls out, it bottoms out and prevents further action)
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I think you found your answer...
Leave your cylinder upside down with the side valves aligned with the marks, center/flapper valve should be in the raised position (gravity), open the side valves fully & then insert pinion rod in the center valve. Just remember when you turn the cylinder right side up, the side valves NEED to be held in place or they will fall out of time.
DoldGuy
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This really doesn't make sense, no matter how many times I take it apart and reassemble it following the manual intructions
Here is the flapper valve assembled first
(http://i.imgur.com/UTyXuge.jpg)
Here is the flapper valve timed correctly from the left side
(http://i.imgur.com/7Mbr8Hx.jpg)
So now I flip the motor upside down and install the 2 side barrel valves so the punch marks point straight out. Then lift them to slide in the main rod(all the way), then push the barrel valves back down to line up the marks
(http://i.imgur.com/vpNckcC.jpg)
Well this is the result after full assembly, when I open the KIPS by hand...the barrel valve aren't even half way opened
(http://i.imgur.com/aQNCP0m.jpg)
Now if i lift the barrel valves and reposition them by 1 gear tooth from the indicator, then when I open the KIPS, they fully open...doesn't make sense!
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Ok...I tried your method of installing the barrel valves and main rack in the fully open position first(using the marks and short tooth indicators), then installing the flapper valve assemblies(small rack, upper pinion rod and flapper fork)
There are a couple problems. A. there is no way to line up the upper rod pinion gear mark with the small rack line indicator
Not lined up:
(http://i.imgur.com/EuRya6k.jpg)
B. The short rack protrudes from the hole when in fully open position:
(http://i.imgur.com/8a2Zvme.jpg)
C. The barrel valves are open by a hair when they should be closed
(http://i.imgur.com/Et04Xx4.jpg)
And for good measure, I don't think the main rack rod is able to fully close to catch the side lever (if i reinstalled the jug back on the bike)
This REALLY doesn't make sense. I'm definitely familiar with KIPS and how they work because I owned a KDX first. This mst be some factory defect where the short tooth indicators on the barel valves were placed incorrectly from the factory.
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See here:
http://www.thumpertalk.com/topic/940930-02-kx250-kips-powervalve-timing/
And here:
http://www.thumpertalk.com/topic/706213-exhaust-valve-timing/
Others with the same issue
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Does your main valve also hang down into the exhaust when its fully open? I actually had to machine a "pocket" into the upper part of the cylinder to let my main valve open on my 2000 kx250. Otherwise it hung down about 6mm.
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Nope the flapper / wedge is ok, you mean it was hitting the piston?
Fwiw I read something about burs building up over time on the flapper valve, you'll have to skim over Eric Gorr's document here:
http://www.eric-gorr.com/images/documents/2-StrokeTopEndAndPerformance.pdf
Somewhere starting on page 18
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If it were mine I would start by taking it apart and cleaning everything.
You may very well discover your issue.
When they are dirty it can be very difficult to see what may be completely worn out.
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Noo they're clean, read the thumpertalk links a few posts back..it's the same issue im having
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My valves SEEMED like they were a tooth off, but as soon as i fully assembled the valves they were fine. The main valve on.mine just wouldnt sit flush with the top of the cylinder when opened. Eric gorr mentioned machining a pocket into the cylinder top as well, but I didnt realize until after id already done it.