YZ85 front brake swap

[wrtimmy]

G'day everyone,

I'm looking at doing some further upgrades to my ('04) YZ85 minimotard braking setup. Currently it's got a standard master cylinder, braided line and an EBC 250mm disc. It's not too bad, but definitely lacks power.

The master cylinder is a 11mm bore, and is the same used in the same year 450f. I've ordered a 450 caliper and aim to make it work. The 450 has 25mm pistons, and the 85, 22mm. So I have some concern of there not being enough 'meat' on the current 250mm disc. Which leads me to my question...

I'd like to mount up a 270mm oversized disc from a 450 to the 85 hub, using 3 of the 6 bolts. I've heard that a 6 bolt CRF disc will fit the 85 hub using 3 of the 6 bolts. Would anyone know, or be able to measure a YZ450 disc/hub bolt pattern so that I could compare to my 85 hub?

Thanks!

 

[wrtimmy]

Might have just answered my own question... been Googl'ing for days and haven't found it but may have just now.

Yamaha:
Front Brake Disc Yamaha YZ450 YZ450F 2003-2010
Dimensions
Diameter 250mm
Thickness 3mm
Bolt Centre 134mm
Inside Clearance 118mm
Bolt Size 6mm
Weight 0.51kg

Honda (CRF250R '07 - that I'm told fits with ever so slightly opening up the mounting holes...)
Front Brake Disc Honda CRF250 R CRF250R 2004-2013
Dimensions
Diameter: 240mm
Thickness: 3mm
Bolt centre: 140mm
Inner Clearance: 101mm
Bolt Diameter: 6mm
Weight: 0.65kg

YZ85:
Wave Disc Brake Rotor Front RM85 YZ80 YZ85
Dimensions
Outer Diameter: 220mm
Inner Diameter: 100.5mm
Thickness: 3mm
Bolt Centre: 120mm
Bolt Diameter: 6mm