Hi, i recently fitted a 3/4 radial master cylinder to my nc calipers worked fine untill i had to use the brakes quite hard. Then the brake lever had no free play and the front brake locked on.
I had to crack the bleed nipples to release the pressure.
This happens everytime when the brakes are used hard.
I have bled a 500ml bottle of fluid and cable tied the brake lever overnite.
No change, its as if the m/c is not releasing pressure. It woks fine cold
Any ideas please

I would check there is a couple of mm clearance where the brake lever touches the master cylinder piston as on some levers you have to file a little bit off to get this clearance i have had to do this twice on two different bikes now hope this helps rick

Was it a "genuine real honest mate" cheap eBay Brembo master cylinder?

If so, throw it in the bin RIGHT NOW. They look ok but aren't made well at all. Poor casting and finishing means you run a serious risk of getting the brakes seized on at any time.

3/4" is usually (depending on stroke ratio) the sort of size you'd need on later bigger calipers anyway, not the nc30/35 stockers.

RICKNC31 wrote:I would check there is a couple of mm clearance where the brake lever touches the master cylinder piston as on some levers you have to file a little bit off to get this clearance i have had to do this twice on two different bikes now hope this helps rick

Sometimes this, sometimes also a need to open up the transfer port hole into the reservoir.

Thanks for the replies, Its a nissin 3/4 m/c, i was using vesrah sintered race pads hel hoses and had good 1 or 2 finger braking until hot .
Ive put the original vfr m/c back on for now but prefer feel of the radial m/c
I do have some 600rr calipers lying around that would need a service and probably work better with this set up but as i need adaptor plates and pads i was going to wait untill the existing pads were worn out.
I will check the lever clearance and does anyone know what size i may need to enlarge the transfer port too
cheers

Cheers rick, when i checked the cylinder was compressed by about 3mm with the lever on its softest setting??
So i took your advice and shortened the piston rod.
I will try the standard setup tomorrow (if it ever stops raining!)
Then retry the radial setup

Still raining!!!

Tried standard m/c and no probs, but i have to admit i preferred the feel and power of the radial m/c
i had mounted the resovoir on a support about 4' long, but noticed the standard gsxr resovouir is mounted on the m/c.
Could this be the problem? If not what size should i open the transfer too

The resovouir mounting will have no effect on the braking.

I just wondered cos thats all i could see that was different to the std gixxer setup