Honda XR250 BAJA Front Fork Rebuild (Part 4): Setting the Oil Level and Fitting a Thrust Bearing Between the Springs

Hello everyone.
This is the final part of my front fork maintenance on the Honda XR250 BAJA (the Japan-market XR250 / MD30): setting the oil level, fitting the WPC-treated springs and completing the assembly.

Home-made fork oil level gauge for the XR250 BAJA, made from a syringe, clear hose and a metal pipe.

This is my home-made tool for setting the oil level.
It's a syringe that can be used with oils, clear hose from a DIY store and a metal pipe that fits the hose.
It's cheap but a bit awkward to use, so if you set fork oil levels yourself, I think a proper tool is a better choice.

I haven't used them myself, but among commercial tools, the DRC gauge apparently lets you set the level with one hand. If you can keep the fork standing upright, a syringe-type oil level tool (such as Daytona's) could also work.

Metal pipe of the oil level gauge marked at 107 mm, the service manual figure for the XR250 BAJA (MD30).

I marked the oil level from the service manual (107 mm for the XR BAJA (Y)) on the metal pipe.

Setting the fork oil level in an XR250 BAJA inner tube with the home-made gauge.

This is how it's used.

WPC-treated fork springs and a can of parts cleaner.

Once the oil level is set, it's time to prepare the springs.
I had the springs WPC-treated (a fine-particle shot-peening surface treatment), and a note came with them.

The note said: “After WPC treatment the parts have been ultrasonically cleaned, but please clean them with parts cleaner or similar before use (on arrival).” So I cleaned them with parts cleaner.

Parts cleaner after washing the WPC-treated springs, slightly cloudy from the cleaning oil.

This is the parts cleaner after washing. It's cloudy, but I think this is probably residue from the cleaning oil. There were no visible particles.

Rag showing the dirt wiped off the fork springs after cleaning them with parts cleaner.

This rag is what I used to wipe the four springs after cleaning them with parts cleaner. This much dirt came off, which shows that cleaning before fitting really is necessary, just as the note said.

Inserting a cleaned fork spring into the XR250 BAJA inner tube while holding the damper rod up with a wire.

Now to put the springs in. Keep the wire that holds up the rod straight, or it will catch on the springs and give you a hard time.

The washer that sits between spring A and spring B in the XR250 BAJA front fork, with slight marks from the springs.

Between the long spring (spring B) and the short spring (spring A) goes the washer in the photo above.
However, I decided to replace this washer with a thrust bearing.

The thrust bearing (needle bearing and washers) to fit in place of the washer between springs A and B.

This is the thrust bearing I got.

Measuring the stock washer between springs A and B with a calliper: 1.56 mm.

The stock washer was 1.56 mm thick.

Measuring the thrust bearing to fit between springs A and B with a calliper: 4.00 mm.

The thrust bearing I'm fitting is 4.00 mm, so it adds about 2.4 mm (4.00 − 1.56) of preload.
I sometimes fit a screen, a smartphone and a 360° camera at the front, which adds weight, so I'm happy with this.

Thrust bearing fitted between springs A and B in the XR250 BAJA front fork.

I put the thrust bearing between springs A and B.

Compressing the springs by hand to fit spring A on top of the thrust bearing.

Next, spring A goes on top of the thrust bearing.
At its free length the spring stands taller than the rod, as in the photo. So the job is to compress the springs and fit spring A before the rod drops down.

I took the photo above while stopping the rod from dropping with my thumb and middle finger, holding spring B down with my thumb and ring finger, and supporting spring A with my index finger and thumb.

Top bolt fitted after installing the springs and thrust bearing in the XR250 BAJA front fork.

I just about managed to fit the top bolt.

Close-up showing that the thrust bearing has the same outer diameter as the fork spring.

The spring and the thrust bearing have the same outer diameter.

Tightening the top bolt and lock nut of the XR250 BAJA front fork.

Tighten the top bolt (22 mm) and the nut (17 mm) to secure them.

Tightening the top bolt into the inner tube of the XR250 BAJA front fork.

Once the top bolt is secured to the inner tube, the job is done.

Both XR250 BAJA front forks fully assembled after setting the oil level and fitting the springs.

Maintenance on both front forks is finished!!

XR250 BAJA inner tube after re-chroming by Toyo Koka.

The inner tubes, re-chromed by Toyo Koka, a plating company in Japan!

Fork bottom (axle holder) cleaned up by DIY wet blasting with glass beads using a Kärcher pressure washer.

And the fork bottoms (axle holders), which I wet-blasted with glass beads using a Kärcher after a lot of trial and error.

: Wet Blasting Fork Axle Holders with Glass Beads and a Karcher (Honda XR250)

Wet blasting the aluminium fork axle holders of a Honda XR250 (XR250 BAJA) with #120 glass beads and a Karcher: masking the anodised tubes, baking soda vs glass bead results, and why the clean-up put me off.

It took a long time to get here, but I enjoyed doing it bit by bit.

If you're working on XR250 BAJA forks, my teardown series compares the internals of these forks (ME08 springs and damping) with the stock MD30 parts:

: Finding a Hidden Racer Setup: Honda XR BAJA (MD30) Front Fork Teardown (Part 1)

Hey everyone! There is always a unique, treasure-hunt-like thrill to buying secondhand parts, isn't there? You never quite know what kind of custom work the previous owner left behind. Recently, I picked up a set of used front forks for my own Honda XR BAJA (Model: MD30 / conventional fork model) and set out to perform a complete overhaul and oil change. Overview of the secondhand front forks waiting for a rebuild However, as I got deeper into the project, something started to feel slightly off. As I tore the forks down, a shocking truth came to light: these weren't ...

Earlier in this rebuild, part 2 covers fitting the seals and slide bushes and tightening the centre bolt:

: Honda XR250 BAJA Front Fork Rebuild (Part 2): Seals, Slide Bushes, Seal Driver and Centre Bolt

Part 2 of rebuilding my XR250 BAJA forks: taping the inner tube, greasing seal lips, using a fork seal driver without scratching the tube, fitting the snap ring, and tightening the ME08 centre bolt while holding the cylinder.