Author Topic: Help with woods conversion  (Read 4464 times)

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Offline kawi600

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Help with woods conversion
« on: April 08, 2009, 01:37:45 AM »
Hey guys, Ive got a 02 KX250 that I just picked up used. Came with a bunch of mods and extras. Looks like factory connection revalved the suspension for a rider of the same weight. Was set up as a track bike so the suspension is all wrong for woods. Its like riding a jackhammer. This is rocky singletrack in the northeast.
I have no idea whats in the front forks, im assuming 5w (I know different brands have a variance on true viscosity) .. but the ride was bad even at 0 on the damping settings. The rear shock was close with a couple clicks of rebound and no compression.

Do you think:
that I can get the suspension to be compliant in the woods by tweaking fork oil weight and level? Looks like redline makes a very thin oil that might lighten the damping.

that its worth sending the suspension out for revalving, or should I have bought another KDX?

That the power delivery is useful for woods riding compared to a KDX?

If I cant get it dialed in Im going to sell it and get a KDX I think. =(


Offline gwcrim

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Re: Help with woods conversion
« Reply #1 on: April 08, 2009, 02:36:25 AM »
A 250 will never make mellow power like a KDX.  Just ain't gonna happen.  Buy the heaviest flywheel weight you can get.  That helps a lot.  Make sure the jetting is right.  Advance the timing.  Drop down a tooth  or two up front.  I love the power of an MX bike in the woods but they can be a handful in real slow technical stuff.

Changing the oil is an inexpensive thing to try for the suspension.  I'm not good with that stuff at all.
~Crim~
You raise the blade
You make the change
You rearrange me 'til I'm sane

Offline KXcam22

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Re: Help with woods conversion
« Reply #2 on: April 08, 2009, 02:55:59 AM »
Keep in mind that the guys who race GNCC start with the KX and not the KDX.  There is lots you can do to make that a great bush bike.   The suspension might be tought to fix if the guy had it revalved.  For starters the PO migh have the forks setup all wrong so a good start would be to take them apart, change the oil and make sure the springs have no preload.  For starters I would look on the race tech site to find the spring rate for you for bush.  Lighter springs, lower fork oil level (smoother) I haven't had much luck on using <5wt oil in forks.  You could try some 2.5W since its a cheap easy test.  Flywheel weight, Vforce 3, Gnarly all make for better bottom end.  Cam.

Offline cxcmoto

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Re: Help with woods conversion
« Reply #3 on: April 17, 2009, 12:30:54 AM »
I have an 03 250 that I use for woods riding almost exclusively.

I have the Gnarly pipe ( huge gain on low end ) and it allows me to ride a gear high and lug it around in tight stuff. Just have to get the jetting right for the pipe and lower RPMs. Vforce3 is also good for improving low-end throttle response. Of course the rekluse does not hurt either for the woods. I run a 14/50 gearing, but am considering going down one more notch in the front. Getting a pro to help on the suspension will shorten the adaptation time drastically. But if you want to do it yourself, use the race tech spring calculator, get the correct springs, then start with factory compression/damping settings or softer and go from there.

Offline The Flyin Hawaiian

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Re: Help with woods conversion
« Reply #4 on: April 17, 2009, 08:16:51 AM »
Ive been racing KX250s in enduros for a while now and they make great woods bikes! There are things that can be done to them that will make them more user friendly. Some things were already mentioned, flywheel weight, FMF Gnarly, V Force etc. I can lug my 04 down to a snails pace and claw through some of the nastiest, slipperiest terrain there is on the east coast! My girlfriend races a 04 KX250 in the B250 class with excellent results. Hers is very smooth. A very good suspension tuner here on the east coast would be Drew Smith from WER or Works Enduro Rider. That is if you cant tune the harshness out the way it is. He's in Northern NJ and does great work. You can also pre load the power valve governor with some shims that are available through your Kawi dealer. This pretty much takes most of the hit out and makes it very controllable. I may have the part number lying around here. Ill post it up if I find it.
A couple of 03 and 04 KXs, a few YZs, 3 PE 400s, a DR and a TS.

Offline kawi600

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Re: Help with woods conversion
« Reply #5 on: August 04, 2009, 03:43:38 AM »
Ok I had the forks and shocks reworked by a local place thats reputable.. but the front end is super harsh despite the valving. They said to go with .42 sprigns due to my weight, but when I slide the forks up in the trees they start feeling more compliant which tells me the springs are too much for the rocks im hitting.
What do you guys run in your woods KX's? I ordered some .38kg/mm springs gambling that they might help get rid of the harshness and let me use the damping.

Offline The Flyin Hawaiian

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Re: Help with woods conversion
« Reply #6 on: August 04, 2009, 07:27:57 AM »
Everybody says to go to a heavier fork spring. I have always gone with lighter springs. All of my YZs, CRs, and KXs were changed to .39s. I dont go by the "spring calculator" that everyone tends to go with, I go by what feels good to me. The suspension guys that I have used here on the east coast all race enduros and have suggested the lighter springs because of our rooty/rocky conditions. Even in the sandy Southern NJ woods, I just adjust the compression and rebound to better suit the terrain. My bikes are well balanced and dont have any weird traits associated with a soft front end.
A couple of 03 and 04 KXs, a few YZs, 3 PE 400s, a DR and a TS.

Offline kawi600

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Re: Help with woods conversion
« Reply #7 on: August 04, 2009, 08:52:55 AM »
My 94 KDX has .35's and it takes the rocks really well. So I think the .38's should be ok if the damping in the forks isnt really tight.
I dunno about the spring weights.. just feels like theyre thinking motocross and not woods. I dont do those insane jumps, this is just a woods bike to me.
Good to hear someone else has gone with lighter than recommended and its worked out.