front suspension change needed?

jaguar

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#1
Primary Problem: front end nose dives on small inclination lipped jumps.

Solution implemented: stiffer front springs and stiffer front compression damping and weaker rear compression damping

Secondary Problem: front is now too stiff on small bumps and the rear bottoms too much from jumps but if I stiffen the rear compression or soften the front compression then the nose diving problem returns.

Race notes: I am only moderately on the gas in 3rd gear because I don’t want to jump too far on this jump since there’s a turn right after it. I can get the front end up if I gas it more and lean back more but I really don’t want to. It’s kind of a coasting jump and other riders don’t have the same problem (probably because they have real race bikes).

Settings:
13 CW front compression (16 is maximum) with 6.7W oil
13 CCW rear compression (16 is maximum)
measured front spring rate at 10 lbs/10mm (45Kg/cm)
front free sag 23mm, rear free sag 22mm
front race sag 44mm, rear race sag 72mm
my weight is 145 lbs
bike is ’89 KDX200

From the sags I’d say the front is sprung stronger than the rear, so then the springs aren’t the problem. I suspect I need different valving but I was hoping otherwise since I have the official fork tool from Kawasaki but still can’t get the forks apart. So I’d have to spend $100 shipping them to the States and then another $100 getting them back (since I’m in S. America).

Last week I solved most of the problem by changing out the 14 year old shock oil which eliminated the stiction and allowed me to soften the front compression setting by one click but its still a little too stiff as it transmits all the little bumps to my hands. What suspension valving (front) would be necesary for this situation? (needed: softer initial fork travel but progressively harder for normal sized bumps)
 

jaguar

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#3
They are less stiff than all my friend mx bikes and the stiffness of the front end is mostly due to slower compression damping which I need to keep the front end up when going over that jump.
It just occured to me that maybe changing out the bushings may help since they are probably original. Old bushings cause stiction. If I changed them then the initial travel would be smoother although the spring rate and compression damping would be the same.
 
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#4
Jag ---For your 145 lbs, a .45 spring is way too stiff [38 is probably about right]. You can put a lighter spring in one of the legs to get an intermediate weight. You said you have the Kaw tool but cant get it apart - well, you're going to have to. Drain it real good, even rinse it, then heat the bottom end of the sliders to around 300 deg. They use a locking compound and the first disassembly is usually tough. Loctite "melts" at 365F and will soften substantially by 300. There's not much in there that heat will hurt [there is a plastic bushing at top of cartridge in the newer forks]. The "clickers" affect LOW SPEED COMPRESSION only - which is exactly what you want [to increase] for jump faces. For rocks, roots & other sharp terrain, you need to adjust the HIGH SPEED COMPRESSION and this can only be done internally by revalving. With an '89 you may not have cartridge forks and may not be able to replace the base valve with a Gold Valve. On my '99, I scrapped the junk stock base valves and installed the GVs --- going way soft on HSC. This eliminated all of that KDX harshness you feel in the bars -- and probably the best $$ spent on any mod so far. Try race-tech.com and see what they offer for your year
 

jaguar

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#5
Yeah I know its stiffer than what would be recommended but its perfect to match the stiff spring of the rear. Let me explain. The 4.7 spring in the rear is for a 180 lb rider. Race Tech recommends a front spring of 45 for a 180 lb rider. So I'll keep it as is and take your suggestion to look into different valving. Thanks also for the tip on how to get the forks apart. I'll try that.
Race Tech don't sell gold valves for the front of my year bike but they do sell the fork emulator kit for $150.
Anyone have experience with it and motocross use?
 
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#6
Someone on the KDX forum -about a month or so back - mentioned that a suspension shop had installed those emulators for him and that they worked great. I believe the thread was about emulators, gold valves and/or Delta valves