USD Fork Oil Change - - Dirtbike at Off-Road.com
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USD Fork Oil Change

Source: Dirtbike at Off-Road.com
I’ll be perfectly honest with you. Even though I’ve played around with a huge number of “regular” forks throughout the decades, I have utterly no experience changing fork oil in the modern USD (upside down) forks. Yep, my expertise took a vacation when the newer bikes came out. Call it lack of interest, or the fact the most of the new bikes that I rode were at press previews.

So, it was with a world of shock that I started to take apart the forks we installed on the Project Honda CRF 230, and ran into the proverbial brick ball. Installation was a straightforward process, but getting the forks “right” was confusing, at best.

I searched through several hundred recent dirt bike magazines and failed to see one article on how to make the fork oil swap. Oh, there were plenty of articles and which titanium pipe to buy, and several dozen pictorials of the very latest sticker kits, but as far as anything useful, forget it.

It was then that I turned my attention to Keith Lynas, owner of OSSA Planet, and all around good guy. I explained my plight and he said “Bring ‘em over.”

Keith walked us through the process, and noted that all cartridge style forks, including a large number of conventional (normal configuration) forks had the same basic system. This meant that many, if not most, of the forks produced since 1986 are cartridge style. You can tell at a glance if the inner rod is hooked to the fork cap when the fork cap is removed.

Refer to your owners manual for the correct oil quantity and type for your particular forks. Ours were 1997 Honda CR125 KYB forks, just about the same (with minor damping variations) all the way up to 2006.

If the photos and captions in our step at a time seem too much for you to handle, then you can have Keith do it if you’re in the area. He doesn’t take phone calls, or nothing gets done in his shop, so it’s best to reach him at: klynas@aol.com, or for general or OSSA information, log in at www.osssaplanet.com. He’s in the San Diego area and knows more about dirt bikes than any man has a right to know.


A spare top triple clamp was used to hold the forks in place while working on them. If you don't have a spare, you can use the top clamp from your forks.

Tighten a fork tube in place using the pinch bolts.

Loosen the fork cap with a l9 mm wrench.

Put a fairly clean drain pan in place. Clean is because you want to measure the oil that's taken out.

Raise the fork tube up and the internals can be seen.

With the internals exposed, the locking nut is clear and a 19mm is on the fork cap.

Hold the fork cap with the 19mm and the lock nut below can be loosened.

With the jam nut loosened, the fork cap can be turned loose easily by hand.

Fork cap can now be removed.

Now the fork spring (and end spacer) can be taken out.

Fork spring removed; the cartridge will fall to the bottom of the forks now.

Remove the fork tube from the clamp holder.

Drain the oil into the drain pan.

Pump the oil out gently. It'll shoot all over the place if you rush it.

Slide the inner rod out.

Here's the complete inner rod removed.

Now pump the oil from the fork tube once again ... slowly.

Take your time and get all the oil out. Do not rinse out with gas like in the old days.

Now you can slide the fork internals out.

Take the fork cap and adjust the rebound damping with flat bladed screwdriver. We used all the way in, then 20 clicks out.

On the compression side, we used 25 clicks.

Reinstall the fork tube in the clamp holder.

Keith used a specal rod holder to keep the assembly in place.

If you don't have such a holder around, you can get by with a large pair of open end wrenches.

Pour the fork in very slowly. Each year has a different capacity. Ours used 460 ccs.

Stroke the inner rod slowly to get the oil to settle.

At first you think that there's too much oil. Keep pouring slowly and pumping.

When the oil is done, reinstall the inner rod.

Insert the fork springs.

Make sure all of the spacers are in place.

Screw the fork cap back in.

Tighten the jam nut securely.

Put a dab of fork oil on the O-ring before the cap is screwed in.

The fork cap can now be tightened down fully.

Replace the rubber plug in the bottom and you're done.

Completed forks, ready to ride.
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Comments and Questions from our Readers
 Posted 2007-08-16 17:29:34.0
I have a question aboout bikes. When comparing a xr200 and a crf230 how much of a difference is there? I know the 230 has only 23 more cc but is it so much of the same bike you wouldnt advise upgrading to a 230 from a 200??
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