I want to replace the Front Brake Master Cylinder on my GPX and add some braided hoses as well, just wondering if I could replace it with pretty much anything? Obviously I wont be going to Brembo Radials or anything, but if i could get a cheap master cylinder off ebay from a slightly more modern bike then guessing it should go on fairly easily??
Anything I should avoid?
If the feel of the brakes was ok, stick to the same size master cylinder.Don’t be tempted to go up a size because you’ll decrease braking power and get a wooden lever.
Cool, how do I tell the size? is it the bore size?
yep, most master cyinders will have it embossed on them somewhere - it’ll be an imperial size (don’t know why, but the the Japs are strange about stuff like that.I used to tear my hair out looking at tech drawings from Japan)
Most likely it’ll be 5/8" which is near enough 16mm
Cheers 
