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Old 02-14-2012, 10:57 AM
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Default 2002 yz250 vs 2002 yz250F forks

Afternoon all,

After doing the customary search I was unable to find the answer I was looking for hence my post for some assistance.
I just bought a very nice 2002 yz250. I was told the front end was overly stiff and would probably want to change to a lighter spring for my son who is like 180 lbs. Some detail was thrown in by the seller that even after they backed out both compression and rebound clickers the forks were still too stiff. Before I bought the bike I called a suspension shop out in Cali just so maybe they'd might be able to shed some light on what I might be up against with these stiff forks. I told him about the clickers and the stiffness being unchanged. The first words out of his mouth were, "there is either something wrong with the fork or the installation of the forks to the bike". End of story he said. He said that if you back out both compression and rebound clickers all the way there is no way the the forks could be still way too stiff. They certainly wouldn't be dialed in by any stretch, but with no matter WHAT spring you have in there, all the way backed out on the clickers would never give you still a stiff feeling. he said to check for fork bind by the forks and front wheel not being assmbled back correctly or something worn, broken or not assembled back correctly in the inards of the forks.
Now that you got the history, heres the question:
My friend has a complete front end off of a YZ250F 2002. If I get into my bikes forks, can I use his as a guide or worst case scenario for parts if something is out of wack? Were the forks the same for the four stroke vs the 2-stroke in that year? I have read where the forks on the 2002 YZF 426 are the same as my YZ's or very similiar where as I can use the 426s' manual to service mine.

Any help would be greatly appreciated. Have a good day all.

Sid
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Old 02-14-2012, 11:11 AM
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Sid -

Welcome to the site.

I still race a 2002 YZ250. I am fairly confident the forks you are asking about are the same.

Tear into what you have and make sure everthing is good to go with fresh oil. A manual would be helpful, too.

If you're in the Tidewater area I can help first hand if you'd like. I have parts and tools for these forks.

Scott
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Old 02-14-2012, 11:49 AM
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Sounds like too much oil to me if the forks are way to stiff. Some people overdo the oilfilling, better first checking that.
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Old 02-14-2012, 11:57 AM
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i am quite sure they are the same. i ride an 02 yz125 and am rebuilding some 03 i think yz250f forks. 96-03 i *believe* are compatible
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Old 02-14-2012, 11:58 AM
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I agree that something is wrong. the first thing i would do is to loosen the axle nut and the pinch bolts. if you still dont have free movement I would then take the caps off the forks and remove the springs and the front wheel and see if you can slide the forks up and down by hand. then you can see if it is one or both of them.
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Old 02-14-2012, 01:08 PM
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I had a 2003 yz250 that i installed 2002 yz250f forks on. They bolted up fine and i ended up liking them a lot better.
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Old 02-14-2012, 01:30 PM
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Default Good replies

Thanks a ton guys. I have my homework cut out for me tonight in the basement. 1st round of the MEGA series is in 3 weeks.

Gotta get ready.

Thanks again.

Sid
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Old 02-14-2012, 07:03 PM
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Default Goin in

Evening guys,

Ok, I loosened the axle nut and pinch bolts for the axle. I then tried to wiggle the lower fork tubes a little now that the stress was relieved by the axle nut. Either of them did not budge in 1 direction or the other. I thought that was strange because at this point you are able to do just that with my CR even though it is a different set-up. I then went to remove the axle through both lower fork points and through the wheel. The axle was fully greased but was a b**ch to get out and through the wheel. I had to get a wooden dowel and use a hammer to drive the axle just about all the way through. Again on my CR, I usually just have to tap the axle a little just so I can get my fingers on the other end to pull it out. Again, I thought this wasn't right. After I got the axle out I looked at it closer and I could definitely see where someone had been sanding or filing on the opposite end of the axle from the axle nut where the axle gets pinched. It wasn't gawled or anything just had been touched. With my eye I took a look down the axle axis to see if I could see any obvious runout or non concentricity between both diameters of the axle. It looked ok and I even slid it back into the wheel to see if it was the axle in the wheel that was tight. Nope, that slid back and forth fine. The axle pinch bolts were just about all the way backed out to ensure to friction on the axle pinch surfaces. I do not think this is right. I'll have to look at this further.

Ok I figured since the forks were off the bike I should probably open them up to check the oil and insides of the tubes to make sure all parts are ok and to make sure they are filled and bled correctly. I loosened the top caps before I removed the forks from the triple clamps. On my CR, I have to either totally run both the clickers all the way in or all the way out in order for one of my adjustments or disassembly sequences to be correct. In this 426 manual I am using for reference I see nothing mentioned at all about this. Should I be doing something with the clickers before disassembly?

Thanks guys.

Sid
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Old 02-14-2012, 07:57 PM
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Yes, runn all clickers all the way out from seated.

Paw Paw
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Old 02-14-2012, 08:38 PM
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Default clickers

Ok, got them both empty of oil and I cycled the damper rod assembly back and forth to get all the oil out. I have not separated the tubes from each other. I only have the top cap off, push rod out, and the spring out. I followed the video from Rocky mountain ATV. This service manual for this 426 leaves alot to be desired. I did not back the rebound clickers at the bottom all the way out as the video didn't say to do so. As I cycled the push rod assembly all the way back and forth to its limits to remove all of the oil, never did I feel any rough spots, sticking feelings or anything on either fork. I also slid the inner tube back and forth inside of the outer also almost to its limits. Never did I ever feel any sticking, binding, rough sections at all. It felt just like they are supposed to. At this point I don't know if I need to disassemble any further or not. I'm thinking now either I have either of a few different things going on giving the "overly stiff" feeling that was described to me. 1. Something was up with that axle being really tight and almost stuck and hard to get out. On reassembly of the front wheel you are supposed to grab the front brake with pinch bolts loose and compress up and down on the forks so that the front axle can find its natural home/resting place. If that axle was that tight coming out, it might be possible that it is never allowed to find its home thereby not letting the forks align correctly. 2. I do indeed have a too stiff spring. Trouble is I do not know what the rate is on the spring that I just pulled out. The manual for the 426 says free length to be 18.1 inches I am measuring 18.25 inches exactly on both springs. This leads me to believe the spring rate with this spring is greater. I also measure a spring wire diameter of .193". Unfortunately the manual mentions nothing of wire diameter. So I have no idea where at above stock rate I am. Any way to find out or tell? 3. Possibly wrong oil weight, oil height, or air not being bled out completely or a combination of any of these three.
Like I said, I do not think I need to go any further with the disassembly of the forks. I have enough possible causes right now and the action of the cartridge assembly and inner to outer tube felt fine. The oil was clean and new that I emptied out so I doubt any ports are clogged or I thought I would have felt that.
Any recommendations for a fork weight for an intermediate 180 lb rider? I will put the new oil back in to the correct height paying careful attention to the air bleeding step. Put the forks back into the bike and try to address the axle tightness problem as well. As far as the spring rate, I have no idea what I have in there now so I don't know where to go.

Any help at all would be greatly appreciated.

Thanks and have a nice night.

Sid
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