Honda XR250 Front Axle: 12 mm vs 14 mm Thread by Model Year (MD30)

2026-10-17

Hello everyone.

The Honda XR250 (including the Japan-market XR250 BAJA / MD30) first appeared in 1995 and went through a series of model changes.
The models are mainly split into early and later types, but there were many small changes too, so a second-hand part you buy may not fit your bike.

Here I'll show the change I ran into around the front axle.

It all started when I decided to overhaul the front forks.
I couldn't ride the bike while the forks were being overhauled, so I thought, "I'll just fit a second-hand pair of forks in the meantime!" and bought some used forks to fit.

But my bike's axle wouldn't fit the second-hand forks. Looking into it, there had been a model change that altered the axle thread diameter.

https://www.honda.co.jp/factbook/motor/XR/19970300/004.html (Honda Fact Book, March 1997, in Japanese. It says the XR250's front axle thread was enlarged from 12 mm to 14 mm to stiffen the steering and improve stability.)

My bike's axle has a 14 mm thread, and the forks I'd bought take an axle with a 12 mm thread.

So I thought I'd just get a 12 mm thread axle as well, and spent a week searching auctions and the like for a cheap used one...

A new, unopened Honda XR front axle (12 mm thread, early type); the part number on the bag is 44301-KBR-000.

I was lucky enough to get a new old-stock one for a few hundred yen!!

Right, that's sorted!!... or so I couldn't quite bring myself to think.

Had other parts changed as well? If I tightened it to the specified torque as it was, would something break?
I got cautious.

First, I looked at how different they were.

Honda XR front axles and forks compared. Top: 14 mm thread (later type). Bottom: 12 mm thread (early type).

Both the axles and the forks:
Top: 14 mm thread
Bottom: 12 mm thread

Look closely and you can see the axle holes in the fork bottoms are different sizes.
The part of the axle that contacts the hub also looked slightly different in length, so I measured it.

Measuring the hub-contact length of the 12 mm thread axle with a calliper: 125.79 mm.

With each axle screwed into its fork bottom, I measured:the 12 mm thread axle was 125.79 mm,

Measuring the hub-contact length of the 14 mm thread axle with a calliper: 128.27 mm.

and the 14 mm thread axle was 128.27 mm.A difference of 2.48 mm!

So it's not a case of being 2.5 mm short when fully tightened, but the other way round. As long as I'm careful not to overtighten it, I think I can make it fit.