Changing Fork Springs?

10 replies to this topic
  • Chris_in_the_Mojave

Posted April 06, 2000 - 07:57 AM


Okay, After last weeks MX races I now know I need stiffer springs in both ends of the bike.

I understand how to do the shock, but the forks are another matter. I read the manual, but it's not that much help on JUST changing the springs.

Okay Guys, what's it take? What "special" tools do you need? Do I really need to do an oil change at the same time to get the oil levels right? Can I do it with the forks still on the bike?

Chris in the Mojave
'98 YZ400F

[This message has been edited by Chris in the Mojave (edited 04-07-2000).]

  • Kevin_in_New_Hampshire

Posted April 06, 2000 - 08:23 AM


It would be much easier to do the forks off the bike. What I do, is loosen the triple clamps and slide the fork leg so the top is between the upper and lower clamp. Snug up on the lower clamp bolts enough to keep the upper tube from spinning as you break the fork cap off it's seat. Don't remove the cap yet. Loosen the lower triple clamps and slide the fork out. Now holding the upper fork leg, spin the cap off. Inside, you'll find the upper cartridge. There is a hex head that is at the top of the cartridge. You'll need to use a wrench on the cap and a wrench on the cartridge leg. Once you break the cap off and remove it, you can pull the spring right off. You do not want the upper fork leg to drop, which it will. This will dump fork oil all over your wifes beautiful white carpet. The spring will be dripping w/ oil also. I hold it above but still inside the fork leg to contain the dripping fork oil. On Honda Showas, it is imperative to not allow that upper tube from dropping all the way down. I would use a zip tie around the lower leg to keep it from dropping all the way down.
It would really behoove you to drain out the fork oil. You will also have to pump the cartridge to get all the oil out of it. I let my forks sit upside down over night to drain them completely. The damper adjuster at the bottom of the forks holds the cartridge in the fork. You'll need something to hold the damper rod to remove this bolt, if you so desire. With the forks apart, you can clean up the inside of the tubes all spick and span with acetone or freon. Don't get any on the seal though. With the spring out, but everything else back together, dump in half of the recommended amount of oil. You'll have to stroke the fork up and down to get the oil up into the cartridge. I have not looked at the book, but it should give you some guidance on how to properly bleed the forks properly. Keep adding the oil and pumping them forks. The level is measured with the springs in and fork fully extended. Remember, it is easier to ADD oil than to suck it out w/ the turkey baster.
Please bounce everything I have said off the manual. If it doesn't jive, ask.

  • Steve_B

Posted April 06, 2000 - 06:34 PM


[The level is measured with the springs in and fork fully extended.]
My manuel says forks fully compressed without spring :)

  • Kevin_in_New_Hampshire

Posted April 07, 2000 - 01:44 AM


Gosh Dude,
That may be absolutely correct...In fact come to think of it, I did have my CR forks completely collapsed. I have yet to work on these specific forks. It has been awhile since I rebuilt forks, and I was WRONG.

Sorry, but I am very glad you asked!!

[This message has been edited by Kevin in New Hampshire (edited 04-07-2000).]

  • Chris_in_the_Mojave

Posted April 07, 2000 - 04:12 PM


Steve and Kevin Thanks for the info! :)

Anybody out who's done YZ/WR forks care to build on their comments? Just looking to get all the info I can from those who've been there before I dig in :D

What I'm trying to avoid is getting in the middle and needing something I don't have, tools, info or parts :D

Chris in the Mojave
'98 YZ400F

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  • Kevin_in_New_Hampshire

Posted April 07, 2000 - 04:52 PM


I used a 14mm wrench to hold the upper cartridge while separating the fork cap from the cartridge. I had to fit the wrench between the spring coils and rotate the spring clockwise (counter-clockwise?) to slide the wrench up through the spring to reach the cartridge bolt. I had to grind down my Craftsman wrench in order to fit it between the spring coils. This may seem difficult to understand. Once you get the cap removed with the spring staring you in the face, you'll understand. If you have any problems or just aren't sure anymore, you can put the cap right back on the fork with no harm done. You'll be fine, Dude!

99 WR, 84 Kaw 900 Ninja, '82 Honda CB750F clothes hanger, '84 Honda Z50 "Berm Destroyer". Always thinkin' "Hell, this worked on my 2 stroke!!"

  • Chris_in_the_Mojave

Posted April 07, 2000 - 06:27 PM


I ordered the springs today should be here around Tues. I'll let you all know how it go's :)

Chris in the Mojave
'98 YZ400F

  • Kevin_in_New_Hampshire

Posted April 08, 2000 - 12:36 AM



If you need my help, you are more than welcome to call me @ 603-942-7105. I start mids next Wednesday night. I work (now this is eastern standard time, mind you) 9:30pm until 7:30am during that lovely time frame. Otherwise I am on day shift until then. I do not expect you to have any problems. I have complete and utter faith in you!

The lower triple clamps need to be carefully torqued. It is imperative you do not over torque them. You can squeeze the tube possibly damaging or hindering your forks operation.

You'll still be alright doing this!!

[This message has been edited by Kevin in New Hampshire (edited 04-08-2000).]

  • YZFWrench

Posted April 08, 2000 - 06:07 AM


Hey Chris-

These forks are really easy to work on, much more so than Showas. I suggest you buy a 19mm 6 point socket for the fork caps, they are easy to damage otherwise.

'00 YZ426

  • Chris_in_the_Mojave

Posted April 13, 2000 - 06:17 PM


It's a done deal :)

Springs came in on Tuesday. Had a couple of false starts, but got it done that night. Lessons learned on the KYB's:

Just remove the handle bars, right off.

Break the caps on the forks loose BEFORE you loosen the triple clamps. This is in the manual, I missed it and had to "reinstall" both legs. You can't just drop down to the lower clamp and use it to hold the fork because the tops are smaller diameter.

Get a bucket to dump the old oil into before you start.

New oil goes in before springs go on...or you GET to take the springs back off :D

You need something to "suck" fork oil out of each leg to set the level. I just dipped a straw and put my finger over the end, slow but effective.

Other than that these forks are easy to work on :D

I changed the shock spring as well. Man what a difference, the bike handles VERY differently. It feels "busier", that took a little getting used to, man what a difference in the woops!! Instead of pounding up and down like a ship in heavy seas, now it just skips across the top. I could ride them much faster!

To my fellow Clydesdale size riders, respringing you bike for your weight is a MUST. :D

Chris in the Mojave
'98 YZ400F

[This message has been edited by Chris in the Mojave (edited 04-13-2000).]

  • Kevin_in_New_Hampshire

Posted April 13, 2000 - 09:53 PM


Sorry about the bum dope on the lower triple clamp to secure the fork in order to spin off the cap. I was relying on my knowledge of my old CR's non tapered forks to get you through your fork spring swap. I am glad it worked out for you!

99 WR, 84 Kaw 900 Ninja, '82 Honda CB750F clothes hanger, '84 Honda Z50 "Berm Destroyer". Always thinkin' "Hell, this worked on my 2 stroke!!"


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