question about handling with kx forks

[28marcb]

Brief overview, I just purchased a 2002 kdx220. The bike is a hoot to ride. However, I've run into a major draw back. On flat sweepers and in sugar sand the front end will Knife under and then lose traction and push. I haven't set the sag to my weight but have checked with my daughter on it. Spot on with her on it so I would imagine it to be to low(probably around 4-4.5 inches) with me. There must be a major flaw with frame geometry for it to still Knife under with that much sag. I have since put a 2.2 inch lowering link from kouba, but have not ridden the bike yet. So my question is does the increase in front end height from kx forks aid the bike in cornering?

 

[NM_KDX200]

Stock fork springs? They're really soft. Nearly everyone replaces them with stiffer springs. My KDX doesn't knife under- I think it handles really well, actually. My '96 XR250 knifed under and my '92 YZ250WR pushed. Never had any trouble with the KDX.

 

[28marcb]

No, mine is defintatly knifing under, I've had to dab the foot a couple of times to keep it up. I put .40 fork springs in and now the rear feels like it is wallowing. I think I could live with it, but I am concerned about putting my daughter on the bike. From my searches I've read about steering stabilizers as a possible fix. I will have to upgrade suspension though so I thought the change in geometry with the longer kx forks might take away from that tendency to knife, thereby killing to birds with one set of forks.

 

[foots]

Short wheelbase... :nod:

 

[adam728]

My bike would knife horribly when stock. Stiffer springs (.40's) and a tire more suited to the sand I was riding made all the difference in the world. It's still a bit edgier than most mx bike's I've ridden though.

Can't tell you whether or not KX forks will help.

 

[Ryan12833]

there is no design flaw it is just not set up correctly. Like someone else said correct springs for the riders weight, a correct tire for sand and then adjust the clickers to suit the conditions will make it all better.

 

[NM_KDX200]

Where are your forks in the triple clamp?

 

[glad2ride]

"There must be a major flaw..."

"I haven't set the sag to my weight"

Say the first one, then the second one, then repeat both until it makes sense. :-)


What is your weight in full riding gear???

 

[Green Hornet]

1st off, if you have the STOCK DUNNY 739 on the front (BURN IT) SUCKS FOR SAND, I think it sucks period. Go with a Dunny 756, 742 or Michelin S12. Your front IS NOT set-up properly (Whats your weight) Also when you turn in sand you let off the gas and when you are INTO THE TURN GAS IT. It you gas it as you enter the turn, YOU WILL KNIFE, PLOW, Whatever you want to call it.
The KX FORKS. If you can do the mod, it is the best thing since sliced bread.

 

[28marcb]

Yes, I havn't set the sag to my weight. I have ;however, set it to my daughter's weight which is 45-50 lbs less than mine. Therefore the sag is only going to be increased with my weight, which should rake the riding position out causing a more stable, less knifing condition. Add to this that I increased the fork springs to .40's, and it still hasn't corrected the issue. I think the problem stems from the short wheelbase combined with a tall overall height. Also I will conceed what I call a problem is great for a heavily wooded, or super tight single track riding. The only time I have the problem is fast, flat sweeping corners and powder sugar. I live in Florida, so all our trails are beach sand and the tracks which we spend about 90% of our time playing on are clay with a dusting of sand over it. Outside of this issue the bike has been absolutley the most fun 2stroke I have ever ridden. If I can improve upon this problem and beef the suspension enough to play a little harder at the tracks, it might be the ultimate all purpose play machine. I mention this because we were really heading torwards a crf230, and like this bike light years more.

 

[Green Hornet]

Marc-You are going to have to set the bike up one way or the other. Sag you can adjust per rider, BUT Springs are another story. Sugar Sand is an extreme surface. You may want to stiffen/clicker up the Forks. Sugar sand, has technique, get the sag set FOR YOU, adjust clickers/stiffen the Forks & Shock and consider the front tire D739 is a medium to hard surface tire. Not good in sand.

 

[foots]

As GH said change them tires...stockers are e*ay material

 

[28marcb]

I appreciate the input from everyone. I have lowered the rear a net of 1.25 inches, and am currently awaiting a new air filter to give the bike a go. Next flat I will change the front tire. I think it has dunlop 490 on it currently. I'll post results of lowered rear after next ride. Still curious as to how the kx front end changes handling traits. thanx again.

 

[Green Hornet]

Take a look at the D952. I have one on the rear and it wears great & hooks up awsome. The only down side is it gets a bit squirily on loose hard pack & since the side wall is a tad shorter, its a PIA to install. Oh Yeah-HD TUBES are a must

 

[krazyinski]

get your but up on that tank,lift your head up, look down the trail and gas it man. on the kdx if you dont get out of the apex of that soft seat the front end will do what it wants cause it just has to much flex to try to man handle it with the bars. the KX forks are a good deal more ridged so that would make a big change.

 

[28marcb]

First ride with the rear lowered 2.25 and the fork tubes pulled up an inch in the clamps. I must say it was a solid improvement over stock. The only knifing came when I was setting up for a corner and was coming in real hot and hard on the front brakes. I also observed no pushing. I have won a set of kx forks and will set the bike up to be an inch lower in the rear(which might mean stock rear height if the kx forks are an inch longer). If the bike maintains its current rideabilty with the suspension set up for jumps It may become one of my favorites.