Shim Stack & Valve help

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Shim Stack & Valve help

Postby curtisa » 11:12 am Dec 17 2010

I've got the '95 KX 125 forks on my '03 KDX 200 and was hoping I could get some help on setting up a shim stack for a Sr. B hare scrambler in N. Calif. Also, instead of buying new gold valves, I've heard of guys modifying the OEM valve. I think the idea here is to open up the ports so there's more oil flow, which allows the shims to play a bigger role. If you're familar, have some pics or can help, please do.

The suspension isn't too bad as-is, but I'm a believer that better susepnsion means faster, safer and faster. By the way, I have an '08 KTM 250 XC, but I prefer riding this little 200. It's a great woods bike and a lot of fun to ride.
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Postby TWMOODY » 07:49 pm Dec 17 2010

Although your forks are different, my KX450f forks were
intolerable for woods riding so I modified the shim stack by
removing 7 of the largest shims.
Very noticeable improvement as it took a lot of the harshness
out of the ride although I still may take a few more out when I
do the fork oil the next time.
I did do gold valves on my KDX and Race Tech does supply
shim charting based on your weight and riding style which
takes a good amount of the guess work out of the picture.

Here's a pic from the removed stack on the KX.


Image
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Postby curtisa » 05:29 pm Dec 19 2010

Big Help, thx
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Postby gregp » 07:42 am Dec 20 2010

You will be very limited by the port edges on a stock piston. You will need to leave enough material for the shim stack to seal well. Also, stock suspension pistons are *very hard* and difficult to grind.
I have opened many pistons up, but it is hardly worth the effort because of the limitations of the stock dimensions.
2004 Dual Sported KDX200
1999 Ninja 250 (Daughter's)
1996 DR 650 (stock, mostly street use)
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Postby curtisa » 02:29 pm Dec 20 2010

You're saying buy new valves? Or should I try a new stack first and see if I can get there?
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Postby gregp » 03:13 pm Dec 20 2010

I guess that I am saying it would be best to try re-valving, if you are still not satisfied, get some Race-Tech Gold valves, or some other after market pistons with larger compression ports.
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Postby gregp » 03:19 pm Dec 20 2010

I usually try to keep the overall height of the shim stack the same, so if you remove any shims, just move them to the top of the stack (directly under the thick washer).
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Postby TWMOODY » 04:07 pm Dec 20 2010

>|<>QBB<
gregp wrote:I usually try to keep the overall height of the shim stack the same, so if you remove any shims, just move them to the top of the stack (directly under the thick washer).



Any reason why you try to keep the height the same ?
I have never seen any mention of the shim stack height,
just the positioning and quantity of different shims.
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Postby gregp » 07:15 pm Dec 20 2010

Yes, often times there is a bleed hole in the shaft that the piston mounts on. This hole lines up with a small hole on the inside of the piston bore. If you change the overall thickness of the shim stack, the holes will not line up correctly. You may also run out of threads on the post when tightening up the nut if you shorten the shim stack.
No sense in letting them flop around in my tool box, anyway.
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Postby TWMOODY » 07:42 pm Dec 20 2010

Makes good sense.
I guess I have never taken out enough to lose
threads on the nut though.
I'll have to take a closer look next time I have em apart.
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Postby Mr. Wibbens » 08:26 pm Dec 21 2010

>|QBB<[/url]
TWMOODY wrote:Although your forks are different, my KX450f forks were
intolerable for woods riding so I modified the shim stack by
removing 7 of the largest shims.
Very noticeable improvement as it took a lot of the harshness
out of the ride although I still may take a few more out when I
do the fork oil the next time.
I did do gold valves on my KDX and Race Tech does supply
shim charting based on your weight and riding style which
takes a good amount of the guess work out of the picture.

Here's a pic from the removed stack on the KX.


Image


What year KX450?

Oh I see it's an 09

I just checked my 07's. I only have 10 of the larger shims

Some of the smaller ones were missing on one side

It's great finding more shit this guy fugged with :mad:
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Postby TWMOODY » 10:12 pm Dec 21 2010

Wibb
Can't tell by the pic you posted on another thread but are
your fork tubes dark in color?
Not sure what else changed but in 09 KYB put a "DLC" (diamond like coating)
coating on the inner tubes to reduce stiction.
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Postby Mr. Wibbens » 10:13 pm Dec 21 2010

yes, mine are coated
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Postby Mr. Wibbens » 10:16 pm Dec 21 2010

whoever had these things was a real piece of work :wink:

I'm missing the 2 11 x .25's on one side and who knows what else
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Postby TWMOODY » 12:01 am Dec 22 2010

>|<>QBB<
Mr. Wibbens wrote:yes, mine are coated


You sure your forks are 07's ?
I didn't think they coated them till 09.
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Postby Mr. Wibbens » 12:09 am Dec 22 2010

Dunno?

I just googled 07 KX450 and found a few pics with coated forks
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Postby Mr. Wibbens » 12:12 am Dec 22 2010

http://www.bikez.com/motorcycles/kawasa ... f_2007.php

48mm inverted, Kayaba AOS with DLC coated sliders, 22-position compression and 20-position rebound dampening adjustment / 12.4 in.
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Postby TWMOODY » 07:49 am Dec 22 2010

Looks like 07 according to Bikez.com
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