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I've read many threads discussing the inverted USD forks vs. conventional.
If I understand this correctly, The 1989-92 KDX had conventional damping rod forks, with the unpopular underhang. The 1993-94 KDX had the inverted USD cartridge forks. Then the KDX went back to the conventional cartridge forks with the unpopular underhang?
While reading the forums, I've noticed the kx125/500-/klx300 USD fork conversion is very popular. Why didn't Kawasaki leave the USD forks (like the ones on the 93-94) on the KDX?

Im sure others can say more and correct

I just came to the conclusion it was a matter of cost for production that and coupled with the fact it was a shorter frame compared to earlier or mx styles. I still like mine but love other brands. The only real thing changed other then fuel injected is front forks really well four stroke as well. The rest is damn near interchangeable for a lot of years and models.

Ive rutted so much rofl but guess used to it now. You've seen one set of handlebars at your ankles you've seen em all.

For what its worth if set with right springs its a great setup for what they intended for the build. Lightweight trail bike. Anything else or aggressive well that's why we are all here reading.

But for sure a downgrade. Picture 160 lb Japanese guy selling a 220 lb American guy a dirtbike. Regardless the kdx has been the most fun project Ive worked on in years.

Thanks for the reply ICRage42. I guess what you say makes sense, the combination of cost and limitations of the bikes intended use.

I think the general perception in the 90's was the USD forks were for motocross and conventionals were for enduro/trail riding. Also Showa and KYB had not worked out there issues with the USD's. Suzuki went back from USD's to the Showa 49mm Conventiionals for I believe it was 98 & 99 on their RM series which were highly praised. Those same conventional forks would come out again on the DRZ series and from what I have read are the best conventionals ever made. if you follow the ol' timers threads on many posts they still say the conventionals are better than USD's and will take a perfectly good set of USD's and get an older set of conventionals. You here the pro's and con's either way. I know when I had my KLX 300/331, which came with USD's they only put one bolt in the lower clamp vs. the standard 2 bolt setup and the reasoning was to give it more flex like the conventionals. I personally think they both can be made to work very well.

I have ****'s racing suspension set up on my KTM USD's, which was very pricey, but an extremely nice setup. I have a set of XR 400 conventional forks on my XR 200, which I am still trying to dial in, (just removed 6 hs shims from stock stack of 12, have yet to ride on trails). With removing the 4 shims from the high speed stack in the stock KDX forks and changing to Mobil1 synthetic I like this setup a lot. It addresses the jarring effect from hitting rocks and the thicker atf slows down the rebound, which they both need to be addressed if you make a change to higher rated fork springs IMHO. I may take out another hs shim or two in the summer, just see if that doesn't smooth things out even more.

In the mid 90's conventional forks had a resurgence. In the Nov. '94 issue of Dirt Bike where they did the first test of the "new" H model KDX200, there is a huge KTM ad in the middle touting the new Marzocchi Magnum conventional forks for 1995. The magazines praised the 45mm Marzocchi's, and most the Euro companies used them in the mid 90's. KTM/Berg then used the excellent WP 50mm Extremes before going back to USD's. As mentioned above, Suzuki RM/RMX also went conventional for a few years.

It's funny the magazines never seemed to mention the crappy under hang and downplayed the flexing in the XR forks. (I remember hating XR600 forks) But then, they never said anything bad about XR's, and ignored it When Scott Summers used USD's. Mcgrath and DeCoster had to fight with Suzuki to use USD's on Jeremy's bikes. The 49mm Showas and 50mm WP are still held in high regard as off road forks.

I don't think it's money, KLX forks can't cost more than KDX units. It seems Kawasaki was just following the trend at the time. Then the H model just got stuck in time since it was never remodeled. The USD fork upgrade for the KDX is almost a must do, even for us trail riders who don't have Mcgrath's or Summer's skills. I did the KX swap to cure flexing and get more precise steering, loosing the under hang is just a bonus.

bcdonyo wrote: The USD fork upgrade for the KDX is almost a must do, even for us trail riders who don't have Mcgrath's or Summer's skills. I did the KX swap to cure flexing and get more precise steering, loosing the under hang is just a bonus.

Is the fork upgrade also a "must do" on the '93-'94 e series? Can those USD's be reworked to be in the same ballpark as KX USD's?

Look on Ron Ayers or some other OEM parts store. There is a huge difference in price between the 1995+ KDX forks and the KDX USD forks.

Keystone wrote: Is the fork upgrade also a "must do" on the '93-'94 e series? Can those USD's be reworked to be in the same ballpark as KX USD's?

I have a 94 and just had my forks reworked. Here is the info I got from the builder;
The forks can not be "tuned" they are fixed dampening and that needs to be balanced using oil volume.
I had .41 (I think) springs installed and he drilled a "balancing" hole in the dampening rod to help the oil balance the fork better. The forks are awesome "right out of the box", he did really good work.
My forks, over all, where in great shape, except the oil and seals. Meaning I didn't need new bushings or anything "fixed".
In the end, the forks work great, but I've only ridden in the trails, including high speed trails. I could live with them as a trail bike but for really high speed stuff, like the dessert, I don't think that they would be nearly as good as a set of tuned KX forks.
I will most certainly let you know after April 6th! I have a 94 KDX with rebuilt forks and a 95 with KX forks (that need to be rebuilt and tuned). I will be riding both bike out in the DEZ in April and can give real world feed back after that!

Was a Race Tech Gold Valve not mentioned as a tuning option?

Jason wrote:Was a Race Tech Gold Valve not mentioned as a tuning option?

It was mentioned, but add $200 to the $250 I paid and your looking at a pretty nice set of (ANY MODEL) forks. So I bought a set of KX forks.
I will have those rebuilt as well, but a little stiffer set up (I think).

I think the general perception in the 90's was the USD forks were for motocross and conventionals were for enduro/trail riding. Also Showa and KYB had not worked out there issues with the USD's. Suzuki went back from USD's to the Showa 49mm Conventiionals for I believe it was 98 & 99 on their RM series which were highly praised. Those same conventional forks would come out again on the DRZ series and from what I have read are the best conventionals ever made. if you follow the ol' timers threads on many posts they still say the conventionals are better than USD's and will take a perfectly good set of USD's and get an older set of conventionals. You here the pro's and con's either way. I know when I had my KLX 300/331, which came with USD's they only put one bolt in the lower clamp vs. the standard 2 bolt setup and the reasoning was to give it more flex like the conventionals. I personally think they both can be made to work very well.

That's me. I've just never warmed up to the USDs. In fact, I still like damper rods.lol

I think the conventionals can be set up very well and that the flex is what makes them so comfortable and forgiving. A USD (with the real difference being the rigidity) wears me out quicker and feels more "twitchy". I don't think I'm any quicker on one or the other but I've always felt like I could settle into a pretty fast pace while conserving my energy with conventional forks. On the other hand, I've never tried a steering stabilizer on a USD fork. That might be a nice setup.

6 Riders wrote:

Jason wrote:Was a Race Tech Gold Valve not mentioned as a tuning option?

It was mentioned, but add $200 to the $250 I paid and your looking at a pretty nice set of (ANY MODEL) forks. So I bought a set of KX forks.
I will have those rebuilt as well, but a little stiffer set up (I think).

OK, it is tuneable, just not cost-effective.