Hello everyone, Boo here.
This time I'm looking at improving the front brake on my Honda XR250 BAJA (the Japan-market XR250 / MD30).
Partly because of my own limited riding skill, I find the XR's brake hard to control.
As I squeeze the brake lever, the brake suddenly bites at a certain point.
To put it bluntly, the brake feels like it only has ON and OFF.
I'd felt this for a while, and riding other bikes made me feel it even more strongly.
One of the other bikes I rode had a front brake that was very easy to control.
Thinking "I wish the BAJA's brake could be like this" is what got me started.
Looking into ways to improve brake control, I found the following options.
- Change to a smaller master cylinder piston
- Change the caliper pistons to Kashima-coated ones
Change to a smaller master cylinder piston
Let's think about option 1.
Making the brake master cylinder piston smaller makes the brake easier to control.
On the other hand, the lever travel gets longer.
In some cases the brake may still be weak even with the lever pulled all the way to the grip, which can put your life and other people's lives at risk, so this needs careful thought.
Now for the planning.
The BAJA's standard master cylinder piston is 1/2 inch (12.7 mm).
A smaller size than this is 11 mm.
Honda bikes with an 11 mm master cylinder and a twin-piston caliper include the following (Japanese-market model names; I only had a quick look, so there may be mistakes).
CBR250 Four (1986)
FTR250 (1986)
Nighthawk 750 (1988)
Africa Twin 650 (1988)
AX-1 (1987-1989)
CB-I/TypeII (1989-1991)
Transalp 400 (1991-1994)
Xelvis 250 (1991-1994)
JADE250 (1991-1994)
VT250 Spada (1988)
Nighthawk 250 (1992-2000)
V-Twin Magna (1994-2007)
CB400SS (2002-2007)
HORNET250 (1997-2007)
VTR250 (1996-2009)
CBR250R without ABS (2011)
CRF250R (2007-2022)
Daytona also sells a Nissin master cylinder (11 mm piston).
Parts for very old master cylinders may stop being supplied, so I ruled those out.
That leaves these as the likely candidates.
CRF250R, and the Daytona Nissin master cylinder
These would cost money, and I'd also have to think about the handlebar area and brake hose routing, so I'll take my time looking into the details.
Now, the other way to improve brake feel.
Change the caliper pistons to Kashima-coated ones
I've heard that switching the brake caliper pistons to aluminium Kashima-coated ones improves brake feel.
I don't know the theory, but perhaps the Kashima coating works better with the piston seals, or slides better?
If there are Kashima-coated pistons the same size as the originals, it would just be a straight swap, which would be very easy.
I'll look into these two options in more depth from here.