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I ride a 94 KDX200 with usd blue forks.They were rebuilt before I got bike and they were done for a 180lb rider.I weigh about 160
Recently I picked up a 1990 with the conventional forks,unsure of condition,probaly stock
Unfortunately my 94 needs a caliper,rotor,and the wheel is pretty hammered and has almost 9000 hard miles on it.
Would it make sense to go to the 1990 entire front end?Every thing on parts bike is good which would make my life easier
Plus it seems like the more people I talk to,the more like the conventional.And seeing as Kawi went back to them in 1995,it kinda makes sense.
Any input is appreciated

Most people don't ride at the level to take advantage of the additional rigidity provided by USD forks,the main benefit is the improved damping capabilities of a modern fork (Which your 94 doesn't have) . If you do this swap the main difference will be in ruts when the underhang catches and knifes you to the inside of the corner. This alone is why I swapped to USD forks.

You should probably stick with the 43mm USD forks on your 94 if you aren't planning to upgrade the front end anytime soon. The 89-93 bikes used 41mm forks, If I'm remembering correctly. Although I think the 93 actually had blue 41mm USD forks. The 94 got an upgrade to the 43mm USDs, and the 95 and up were fitted with 43mm conventionals. Basically the 94 and up forks are quite a bit more substantial than the 89-93 variants, in my opinion and your mileage may vary and all the usual disclaimers.

I do believe the 89-92 N. American conventional forks were a KYB 43mm inner tube and 93-94 USD's were a 41mm. Then back to 43C's in '95+ with upgraded springs/valving. Compression adjuster maybe?

Source: The P's OS used to be on my bike

93/94 forks are the same....added info, the 93/94 uses the same wheel as the 95+ KDXs.
I would rebuild the wheel and caliper and buy a rotor from RMATV for $60. I wouldn't consider the 89-92 forks worth using w/o a ton of $ put into them.

All correct, yes. Sorry I was typing while drinking and watching a movie with the wife and got that all mixed up. Should know this well, as I've had and done at least seals and bushings on all of the above at some point in time.

At any rate, 93 and up forks should still be more competent than the 89-92 forks. My memory might not have matched up the sizes properly, but still, the 89 - 92 forks were damping rod conventionals, right? And 93/94 cartridge style USD, and then 95+ would be cartridge style conventionals. So the reasoning was off, but the conclusion is the same.

Looks like '93/'94 had considerable different spring rates too. I was just checking racetech for fork info, I never realized how much they changed the spring rates each year; Check this out

0.296kg/mm in '89,
0.298 in '90,
0.304 in '91,
0.300 in '92 and '93,
0.296 in '94,
0.345 in '95/'96 and settled on 0.35 for '97-'06

Gotanubike wrote:Looks like '93/'94 had considerable different spring rates too. I was just checking racetech for fork info, I never realized how much they changed the spring rates each year; Check this out

0.296kg/mm in '89,
0.298 in '90,
0.304 in '91,
0.300 in '92 and '93,
0.296 in '94,
0.345 in '95/'96 and settled on 0.35 for '97-'06

And all of those spring rates are pretty useless for a full sized rider. I've ridden all 3 fork styles and my conclusion is that the 89-92 forks suck real bad, there should be no reason to put those on any bike, besides keeping it stock. I put my 93 forks on my 95, just because the forks where built for me and the conventional forks where not. I'm trying to save up enough money to get a set of 95 RM forks mounted up

Yep I spent a considerable amount of time and money rebuilding my '90 stockers last spring(check sig) and now they sit in the corner of my shed

Bottom line I'd say do what you can to make the 94 USd's work You could spring up the 1990 conventionals for your weight and riding style, only thing is being damper rod forks they are really not valved very well and lack compression adjustment.

I agree with everything said above to a point...my brother has a 92 and I have a 97 and I have ridden them back to back and the forks imho were equally horrible regardless of oil height/weight/clicker adjustments. Once I went past third gear I was never sure what the front end would do. That said for tight gnarly stuff both were magic. I haven't ridden better forks for slow stuff.

Swapping...easier? yes. better? no

underhang
cartridge vs. damper rod

DUDE!! They're blue!

masterblaster wrote:I agree with everything said above to a point...my brother has a 92 and I have a 97 and I have ridden them back to back and the forks imho were equally horrible regardless of oil height/weight/clicker adjustments. Once I went past third gear I was never sure what the front end would do. That said for tight gnarly stuff both were magic. I haven't ridden better forks for slow stuff.

After I put in .44 racetech springs in my USD forks they felt amazing (compared to before). I can ride really fast across all sorts of terrain. Feels like I'm riding on a magic carpet. But they're really stiff when it comes to the tight stuff. It's really draining when going slow over rocky terrain. I guess you can't have it all.

I couldn't agree more, I recently did a fork and shock swap and ruined my bike for anything less than race pace...fwiw the very best overall suspension I have ever rode was on a 96 yz125 (set up by devol for a 170lb slow intermediate) seriously it was my magic carpet. When I get around to building a hybrid this is what I'm going to use.

I weigh 165 and .41 springs work perfectly at all speeds for me. The early 2000's yamaha 125's are about that rate and are easily revalved modifying the compression stack only and using 2.5 wt fork oil at 120mm. I've used 3 sets of yamaha 125 USD's on KDX front end conversions over the years and all were great with the stock springs.

Another plus regarding the yamaha triples 2001 and up, is the handlebar position is moved forward about 1/2 inch which really helps ergo-wise and handling wise. I use fatbar adapters that raise the bars enough to clear the raised longer forks in the triples (about an inch or so above the top of triple). Much better ergos for my 5'10" body and better handling too without shortening the forks.

Here's a video of me riding on the 220 with this fork setup - the terrain is rough enough to get an idea how they work.

I fail to see the single track

Nice bike! I kept the stock purple seat and ratty plastics on mine to enhance the whiskey tango foxtrot effect for the 250f guys I pass in the air

Thanks for the great advice.
Im keeping the usd,until I decideto do a better fork swap.
Glad I asked here before wasting my time swapping things to find out it sucked

kawagumby..what do you do when you are zipping along the cliff edge trails and meet someone from around the corner also zipping along the cliff edge trails???

Jason wrote:kawagumby..what do you do when you are zipping along the cliff edge trails and meet someone from around the corner also zipping along the cliff edge trails???

Cali not only has those smooth and wide single tracks, but they are one way also. The two track looks like a road

They are SUPPOSED to be one way.