1981 KZ650-CSR w single disk front brake & stock Fr master cylinder.
I'm refurbishing the Fr br master cylinder. It wasn't leaking prior to removing it from the bike. When I removed the piston liner & dust cover, there was what looked like crusty brake fluid residue. not much. I'm assuming a little buildup over time would be normal from the normal action of the piston's movement. Would that be a reasonable assumption?
AFAIK, a new piston assy kit isn't available for the 650-CSR. neither oem or aftermarket. The 650-B2/B3 piston assy appears to be a very close match, so I may try that kit if mine leaks.
That film sounds normal. That said, I'd try to find a new seal for the plunger and maybe a new dust boot too if possible. 35 year old rubber parts should be replaced when possible.
The brake was working fine, but the paint was messed up around the reservoir cap. I was thinking that by disassembling & cleaning it, that the piston might start leaking. I guess I'll find out soon enough. hee. I'm not sure if the earlier 650 kit will work & didn't want to risk wasting money yet. I'm expecting to install a Honda master cylinder anyway, but I wanted to see if my refurbishing stuff worked on the stock unit. Thanks.
