SS Brake Piston

[philward]

Just thought I'd give some feedback on a SS front brake piston I bought several months ago but problem has occured on first roadtest.
Bought this of ebay

 - https://www.ebay.co.uk/itm/Honda-CB750-K-Four-Front-Brake-Caliper-Piston-Stainless-Steel-Seal-KIT014/252510162295?fits=UKM_Make%3AHonda&epid=0&hash=item3acac74d77:g:Wy8AAOSwHnFV2rbG

Fitted it and only just road tested the bike (after recent completion) and had loss of presure in caliper. On inspection the seal was damaged and so ordered another seal but same issue (piston was a struggle to get in). On checking the piston and mictometering the diameter is spot on to original Honda. However, the leading edge taper is smaller and this 'sharper' leading edge of the piston catches the seal and damages it when fitting the piston into the caliper. Fitted new seal with original piston and slotted in easier. I then machined the taper on the SS supplied piston to the same as the genuine Honda item and SS piston slotted in fine and sealed properly.
I have contacted the seller to advise and it may be a batch issue but thought it might be worth letting members know to avoid potentially dangerous consequences

[Bryanj]

I have fitted several 400/500/550 sets from him with no problems so you are probably correct about batch problem