Rear master cylinder

[Patvail]

Hello,

I'm in the process of turning an 84 GL1200 into a trike. The new axle came with drum brakes, all the lines have been replaced. I bled the lines on both sides and the front. The brake peddle has little resistance, it feels like the master cylinder isn't moving enough fluid. The emergency brake works well, and when I hit the brake peddle I can see the shoes move, but just not enough.

Both front and rear brakes worked fine before the mods. They were a little spongy, that's why I replaced the lines and hoses. Could my master be leaky ? Is there a larger master cylinder I could use ?

Any input will be appreciated.

Thanks