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treelimb
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Location: Cedar Bluff,Al.

What's up? It's me again----

Post by treelimb »

and i'm searching for that extremely VARIED assortment of answers/opinions only aquired here on KDXRIDER. I do appreciate the replies to my last post.THANKS.
Here goes-
The suspension CZAR that did my bike up stated that the forks had been re-valved (or ?) and had a KX 250 valve installed. The original owner,from whom I bought the bike w/the original front tire still on it, had stated that the forks had a KX250 cartridge put in.Apparently he was a bit off which matters not as I remain ignorant regardless,bringing me to you,KDXRIDER's.
What has the KDX250 valve done for the bike as opposed to say a Goldtech Valve or similiar,other than saving the first owner money,if that?
FYI-the rear shock had been sent off to Jeff Fredette for a revalving as declared by the original owner/paperwork/confirmation as to a revalve job by my CZAR, all to my immense delight.FINALLY a straight up and honest seller from whom i bought something!! They still exsist.
I still think that my forks are under sprung for my weight,about 180lbs.in gear w/water or beer,due to the PLUSH feel.Granted I have really not spent enough time on the bike w/re-done suspension;plenty of time on it w/shot fluids and etc., other than the one race i wrote about and ride time in DA woods around here. I know your boy Fredette suggests the .38 springs,but being an OLDMAN from agone by era,I really do not know just what to look for in the feel or ride as I ride.SO can anyone,in layman's terms, describe how my bike and it's suspension should be feeling in DA woods(cool moniker)? Thus far all i have raced the bike in/on is mx.I am about to start SE & TRA and GNCC w/a long time friend and hopeful mentor of mine Gerald Greshem,#1 in super senior B, 50+, GNCC,(and on a 2005 YZ250,STOCK,except different flywheel) at his prodding and HOPEFULLY his guidance.Therefore i need to be confidant in all areas,suspension expecially b4 I am taken in tow by an old pro.I would rather not badger him w/a bunch of ass-wipe questions on suspension,the answers i should know from when i raced long ago,even thougjh i never raced woods/hare scrambles/enduros as i now will be.
YES I KNOW I TEND TO TYPE TOO MUCH but it is another
I GOTS TO KNOW deal and you need as much info as possible to base your varied/APPRECIATED replies on.
Thank you all in advance and i hope to read the entire spectrum in replies.
treelimb
KarlP
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Post by KarlP »

At 180, I'd say the .38 ought to be O.K.. If you got money, you might try the XR400 springs from a '99 and up XR40, I believe.
If you got a bit more money the KX forks are really the way to go. Seems like a whole kx 125 from the late '90's through current models go pretty cheap these days. Take the forks and part the rest or use other bits to upgrade the KDX.
A far as how it should feel when it is suspended right, that ain't an easy question to answer. How about it should track straight and predictable under power regardless of terrain? big difference in set up between MX and woods.
I see you're in GA, come down to AL and race the Clanton enduro in May. Finish that with dignity and you'll be all set!
'08 KTM200xc
'99 CR/KDX Hybrid with that RB stuff done to it
KX100 for the boy
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bradf
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Post by bradf »

To keep it simple, the bike’s suspension has a lot going on at any given time. Valves/shims/oil provide active progressive damping. In simple terms, valves/shims/oil only affects the suspension when the suspension is moving either in or out. They affect the speed at which the suspension moves for a given amount of force applied. The spring’s force is linear and applies force in one direction, to get the suspension back out to neutral (extended). At the same time the springs are continually resisting any added compression so they are active in the compression circuit as well and stay active even when the suspension quits moving.

Balance is critical. Picture a 500 lb weight slowly added to the pegs. This is virtually the center of balance on a bike. If the suspension is “balanced” both ends of the bike will move at the same rate. The added weight is slow enough that the valving doesn’t play a role at all. If this weight is dropped on the pegs suddenly (0-500 lbs in 1/10 second) then the valves will progressively resist movement and it is highly possible that one end of the bike will compress ahead of the other.

The correct spring rate would be one that keeps the bike balanced. Not too heavy as to not let the suspension travel through its entire range of travel but still allows it to bottom out occasionally, and yet not be so weak that the suspension is bottoming on normal hits and landings. That is why the total of unsprung weight including the rider is the major determining factor in spring rates, not riding conditions.

Valves/shims/oil are the major determining factors for riding conditions, not springs. Sharp edged trail bumps usually are contained in the first few inches of travel, i.e., 3 inches of travel in 1/10 second. They are dampened by the valves/shims/oil resisting to the change. Hitting a whoop doing 45 would compress the suspension at 4 times the speed at 12 inches of travel in 1/10 second. Suspension set up for the trail would allow this to travel through the first few inches of travel far too easily with too little resistance and it would shoot through the travel all the way to bottoming. The suspension change to handle the whoops would be to increase valving/shim/oil progressive resistance to slow the travel down by becoming “progressively resistant”. On later KX forks the mid-valve would come into play and handle this load. To make this change from trail to whoops by using a heavier spring would mean probably putting in a 3X larger spring rate. But then back to the balance being way off.

That’s the simple explanation
'04 220 w/'01 KX250 USD forks, '02 RM125 Showa shock, Rekluse EXP 3.0, LHRB & all RB'd
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