How do you know if the front forks are too long

[Gixxer340]

Hi All,

I have a 2001 KDX that I bought with the front end already swapped to a KX (unknown year and CC at this point). I have a feeling that the forks are too long but I am not sure how to measure to find out since I didn't have the bike with the previous setup to get any initial measurements from. Does anyone know the correct way to measure the height of the bike to determine if the front end is sitting too high?

Here is a pic of the bike for reference.

Thanks

[KDXGarage]

Read around. I think a few have posted stock length. You could use their measurement to compare to yours.

[SS109]

Do you know what the forks are from? They look like '96-'98 KX125/250 KYB's. I just see what the travel difference is compared to the stock forks and slide them up the same amount as a starting point. My current forks have 1" more travel than stock so I have them up 1" above the top clamp. This method has worked great for me on two conversions.

[John_S]

I just measured my stock 02 220. My forks are sitting all the way down in the triple clamps. The bottom of my fork cap is sitting flush with the top of the upper triple clamp.

The bike is on a stand and the measurement from the axle center line to the top of the upper triple clamp is 37 7/8".

EDIT: Eyeballing the tape measure running up the fork tube...it looks like its right at 27" from the axle center line to the bottom of the steering tube for another reference.

[Gixxer340]

Thanks for the reply's. John_S, Thanks for the measurement. I assume "The bike is on a stand" means the forks are fully extended. If not, please confirm.

The forks are from a 2000 KX250 from what I was told.

Again, Thanks

Jeff

[John_S]

Thanks for the reply's. John_S, Thanks for the measurement. I assume "The bike is on a stand" means the forks are fully extended. If not, please confirm.

The forks are from a 2000 KX250 from what I was told.

Again, Thanks

Jeff

No problem Jeff. I just edited my comment with another measurement for reference. Yes the forks are fully extended. I just picked up a set of 2000 KX 250 forks and triples for a swap. With the new forks and triples sitting on a bench (forks all the way down in the triples) the measurement is one inch more (38 7/8") than my stock setup at 37 7/8". I was hoping to run them just like that with one more inch of travel. My bike would be sitting like SS109's at one inch higher but my forks would be all the way down for whatever reason. The spring measurements are right on the higher side of the 2000 KX service limit lengths in the manual. The whole set up looks like they're brand new off of a showroom 2000. I scored them for $130. Forks, triples, and bar mounts. I was shopping for springs for my forks when I found them and couldn't resist. I had them in the living room the other night staring at em lol.
EDIT: I haven't done the stem swap yet so maybe that measurement of 38 7/8" will change with the KDX stem.

To me KDX's look like they sit too low in the front to begin with. Look at the brochure side view for example. I'm interested in hearing from others if the stock geometry is so good that its the number we should be shooting for.

I like the way your bike is sitting. Good luck and let us know what you find.

[SS109]

To me KDX's look like they sit too low in the front to begin with. Look at the brochure side view for example. I'm interested in hearing from others if the stock geometry is so good that its the number we should be shooting for. I like the way your bike is sitting. Good luck and let us know what you find.

Funny as I always thought it looked the opposite! However, you're probably right especially considering how Kawasaki saddled the KDX with an unbalanced suspension.

All geometry is adjustable to suit a rider's preference. It's a balancing act between quick turning vs stability. Lowering the rear or raising the front will normally make a bike more stable at speed at the expense of the bike not wanting to lean over in to a turn and slower turning overall. Raise the rear or drop the forks and tighter quicker turning is the result but high speed stability will suffer.

Whatever you do, make sure you have the proper springs in the forks for your weight and recheck your race sag after your fork swap to make sure your still at your preferred setting. The Pro Circuit Kawasaki guys recommend 100mm race sag on all KDX's with a static sag in the 30-40mm range.

[IceCold4x4]

To me KDX's look like they sit too low in the front to begin with. Look at the brochure side view for example. I'm interested in hearing from others if the stock geometry is so good that its the number we should be shooting for. I like the way your bike is sitting. Good luck and let us know what you find.

Funny as I always thought it looked the opposite! However, you're probably right especially considering how Kawasaki saddled the KDX with an unbalanced suspension.

All geometry is adjustable to suit a rider's preference. It's a balancing act between quick turning vs stability. Lowering the rear or raising the front will normally make a bike more stable at speed at the expense of the bike not wanting to lean over in to a turn and slower turning overall. Raise the rear or drop the forks and tighter quicker turning is the result but high speed stability will suffer.

Whatever you do, make sure you have the proper springs in the forks for your weight and recheck your race sag after your fork swap to make sure your still at your preferred setting. The Pro Circuit Kawasaki guys recommend 100mm race sag on all KDX's with a static sag in the 30-40mm range.

yup the zrx guys flip the eccentrics to raise the back of the bike an inch or so to help it flop into the corner. Set mine that way and never looked back. I do have to wonder how far you could go in that direction on the dirt bike before it really gets unstable at the speeds we honestly travel (doesn't apply to the guys who sumo and ride the street of course )

[Gixxer340]

Ok, I did some measuring. My measurements don't seem to make sense though. I got about 28 1/8 to the bottom of the steering neck and about 36 3/4 to the top of the triple. That is with about 10mm of the fork sticking up through the top of the triple clamp. Now, I do have a TAG upper triple clamp (not sure if that matters). Here are some pics of the measurements and finally, a pic of the bike with both wheels about the same distance of the ground. Thoughts/opinions?

[MaverickAus]

Does it ride OK? If so why worry about it? It looks fine to me.

[Gixxer340]

It does ride fine. I just get wrapped up some time is "is it working as well as it could". First world problems, you know. I did order a set of 15mm handlebar spacers so I can experiment with moving the forks a bit higher in the triple clamps, but it is probably unnecessary. I just can't help but tinker.

Over all it has been a great bike so far, I just need to tackle a bad front rotor and squishy front brake and it will be about perfect for me.

Anybody have a spare front rotor lying around?

Thanks to all for the input

Jeff