Topic: CB550 MC piston bore size?

[n9viw]

Hey all,
   I'm considering some brake work, but I need to know what the original bore size of the 550 is to know if my new master cylinder is a sufficient bore size. The one I'm looking at is 5/8" (15.875mm), but I can also get one in 3/4" (19.05mm). Will the smaller one provide sufficient brake pressure?
Thanks,
Nick

[bwaller]

I thought most modern masters were 5/8 which is larger than the 550 original. What does the 3/4 belong to?

[volz1fsu]

The 5/8" will give more pressure and less volume of fluid than the 3/4".  If you use the 3/4" the lever will move less and it will be harder to pull.  You should go with the 5/8" if you have the stock front caliper.

[dusterdude]

3/4 is for dual discs

[bwaller]

I'm curious to know what bike uses a 3/4" cylinder, anybody know? Maybe a big ole cruiser. I have seen a 17mm model but alot of sport bikes use 5/8 and they all run dual discs.

[dusterdude]

i know harley uses 5/8 on single discs and 3/4 thereabout for dual discs.