1990 KX500 front end - no go?

Questions and comments about converting to beefier forks..
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Kawboykid
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1990 KX500 front end - no go?

Post by Kawboykid »

My current KDX is a 1992 KDX200E4

I just found a local guy selling a complete 1990 KX500 front end (minus the steering stem). Everything else is there and fully assembled: wheel w/new tire, axle, brake caliper, line and master, forks w/guards, both triples, risers & bars. I was all pleased with myself that I talked him down from $450 to $100, but before I get too excited I figured I'd better check with the experts here. Reading some of the other threads in the Fork Conversion board I am hearing that 96-04 KX500 front ends are the ones to find, and wondering if maybe I should pass on this setup.

Will the older KX500 forks not fit at all? Or are the newer ones just more desirable because of more modern design?

Will my KDX stem press into the KX lower clamp?
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Re: 1990 KX500 front end - no go?

Post by KDXGarage »

Be aware that one has to buy custom springs from Cannon Racecraft at around $175. Race Tech and Eibach don't have them. With no stem, that is a bit of a hassle on the stem. If it had the stock stem, it would just bolt right up.

It is tough to find a few rates of springs for even the mid 90s KX forks now.
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Re: 1990 KX500 front end - no go?

Post by Kawboykid »

Thanks KDXGarage. I was concerned about the absence of the steering stem (kind of negates picking one of the "bolt up" fork swap donors, right?) as well as the need for revalving/respringing mx forks for use in the woods, especially the gnarly tight-but-soft sand single track we have to ride here in the Philly/NJ pines area.

I appreciate the honest advice. Sounds like I should either just rebuild/revalve and respring the conventionals that came on it or hold out for a better swap. Thanks!
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Re: 1990 KX500 front end - no go?

Post by KDXGarage »

It is always a tough choice on which way to go. I will give some thoughts on (YES, get it) instead of passing on it.

What is your weight in full riding gear?

If I ended up with the parts you mentioned, I think I would just buy a set of 1990 clamps off eBay and try to sell what came with the front end for ANY price to offset the cost. When one swaps out the KDX stem, then the KDX clamps are pretty useless and sold for the previously mentioned "ANY price".

After the KX front end is set up and tested to work well, the KDX parts could be sold off to help recover the cost of buying the KX parts.

I can't see going to the trouble of swapping a stem into that clamp.

I looked on Race Tech, and the fork springs are supposed to be .39 stock. Maybe that will be close to your ideal rate or maybe close enough in your opinion.

I did not consider the purchase of an additional set of clamps (or a lower with a stem) when I first replied. Considering that and if the rate is pretty close, that makes it much more attractive in my mind.

I AM NO HELP. :-)
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Re: 1990 KX500 front end - no go?

Post by Kawboykid »

Oooh good idea! I hadn't considered trying to find another set of kx500 triple clamps. That would definitely make it easy, if I could find a set for around $50 or so that could tip the scales...
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Re: 1990 KX500 front end - no go?

Post by KDXGarage »

What is your weight in full riding gear?
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Re: 1990 KX500 front end - no go?

Post by Kawboykid »

KDXGarage wrote: 02:54 pm Nov 22 2018 What is your weight in full riding gear?
Wow I snoozed on this thread bad. I have been looking into stiffer springs for rebuilding the stockers as a stopgap, but am still thinking about keeping my eyes open for the best USD.

My weight in full gear is 160-170, so I don't need super stiff. Am currently looking to put 0.33 kg/mm H series stock springs in my E forks and heavier fluid to get me moving this season (my local club's first enduro of the season is in March) and then look out for better swaps.

Any advice as to the best/easiest swap to look for that might not need resprung for my weight?
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Re: 1990 KX500 front end - no go?

Post by KDXGarage »

1995+ springs are 0.35.

If you are 165-ish in full gear, you are going to be pretty close on any stock springs in 1990's KX forks. Check rates on partzilla diagrams.

You would probably be around a .40.

Look at what a current off-road bike weighs, then look at the spring rates on them. You are about what Japan thinks a rider weighs, so you can learn a lot from that.
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