hi brand new member here and just recently got my first kdx its a oldie but goody i love this thing.but i am having some front fork problems and wont to replace the forks with some better than whats on it.but my problem is money so if anyone has any good ideas for me that are kinda cheap it would be great to here them.I am around 220 with gear on.thanks
front forks 1989 kdx 200
- Thread starter bttow49
- Start date
dirt bike dave
Sponsoring Member
- May 3, 2000
- 5,348
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The cheapest things you can do are add some oil to improve bottoming resistance, and stiffen your springs by cutting off a few coils. Those two things are very cheap and will make a big improvment.
Short of replacing the forks, you can make your forks much much better by buying the right springs for your weight and adding Race Tech cartridge fork emulators. Not sure what the emulators cost these days, but it's a night and day improvement on the old '89 damper rod forks.
Short of replacing the forks, you can make your forks much much better by buying the right springs for your weight and adding Race Tech cartridge fork emulators. Not sure what the emulators cost these days, but it's a night and day improvement on the old '89 damper rod forks.
You can use kx forks but you'll need the entire front end including triples. It takes some minor modding to get them on. You can also use KX500 front end as a bolt on, but again, you need the complete front end. There is a lot of information in the fork conversion section on kdxrider.net. I'm currently working on getting a set of yz250 forks installed. There not great forks, but should be a worthwhile upgrade considering I got a complete front end for free.
J.
J.
- Thread starter
- #7
well i have a major leak in the seals but i also don't have rubber boots on i know i need to have them on got the bike with them already removed.so with the seal facing up they collect alot of dirt so i was thinking of pulling them off and cleaning real good and put boots back on for now.hope to completely rebuild forks over the winter but want to still ride.whats the best way to clean them and how much fluid should be in them?
dirt bike dave
Sponsoring Member
- May 3, 2000
- 5,348
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Joburble said:
Cutting a spring makes it stiffer through all the remaining travel. Adding excessive pre-load is not the same thing, and would be very resistant to initial movement. Also, have you ever tried to install a fork cap on a spring with 2" of preload? Might be tricky.
Here is how cutting a spring makes it siffer:
Let's say your spring is 0.35 kg/mm and it has 50 coils. If I put a 3.5 kg weight on the spring, it will compress 10 mm. Basically, the gap between each coil will decrease by 0.2 mm.
If I cut 10 coils off the same spring and put the same 3.5 kg weight on it, the space between the coils will by compress 0.2 mm x 40 coils, or 8 mm. The spring has got 20% stiffer, and would be 0.4375 kg/mm.
You usually can't cut 20% off a fork spring length because you will coil bind when the suspension bottoms out. YOu need to measure the gaps between the coils, multiply by the # of gaps, and find out how far the spring can compress before coil binding. Let's say it's 13". Then deduct how far your forks can travel, say 11.2". Also deduct the amount of pre-load you want to run, say 0.3". So of the 13" of compression the spring can make, you have already spoken for 11.5". You could safely shorten (and stiffen) that spring about 11.5% (1.5"/13").
I've cut 10%+- off of KDX springs before and it worked great. Noticeably stiffer.
After cutting the springs (with a torch) he will have to add spacers to regain normal pre-load. Washer's work great and are cheap, as well as easy to fine tune.
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There are lots of forks that can be had cheap which are much better than the spindly and generally crappy KDX forks, especially the old 89-92 models. Problem is, most forks you get cheap are going to need extra work to get them up to snuff. They will have to be rebuilt, sprung for your weight, and set up correctly. Then you need the front wheel, caliper, triple trees, etc. By the time your done your cheap forks are no longer anything even remotely close to cheap. However, it's not cheap to build up the forks you have either. The cartridge emulators are not cheap, and even if you build them up you still have a set of forks with no rebound adjustment. The rebound can be adjusted by using different weight oils, but that's quite a hassle for a small adjustment.
Anyway, just throwing some info out there. There are certainly mods that will make those 89 forks perform better. If feasible, a set of MX forks is the way to go IMO. Do some reading on fork conversions over at KDXRider and go from there.
Anyway, just throwing some info out there. There are certainly mods that will make those 89 forks perform better. If feasible, a set of MX forks is the way to go IMO. Do some reading on fork conversions over at KDXRider and go from there.
domino dave
Member
- Sep 24, 2003
- 136
- 0
You said you have a major leak. You can't just clean and put the boots back ... you need to replace seals and boots or your forks will never work right. It's not that hard a job. You also said money is an issue. Jeff Fredette sold me some takeout springs that were heavier than stock... CHEAP!I'll be back in just a minute.... Davebttow49 said:
domino dave
Member
- Sep 24, 2003
- 136
- 0
For your weight, and money issues, you could call Fredette and see if he has some heavier takeouts he could send you. He also gave me complete instructions how to set them up. Fluid , preload, etc. I've never tried cutting the springs ... but sounds like that could be another alternative...cheap. Click on here.http://www.shopfrpoffroad.com/index.htm
domino dave
Member
- Sep 24, 2003
- 136
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Whatever you do , get those seals replaced... Dave
i am very new to KDX and off road bikes in general. How can i tell my front forks are ok with the oil level?. I also own a kdx 200 1989. When i ride in a very rocky road, i can hear some snaping on the front, but not very shure where it came from. I guess the forks. Never done anything to the forks sonce i have the bike. 5 years. Thanks !!
