Topic: 1978 550k Master Cylinder Rebuild

[Farley121]

  Hi All,

  Im needing to rebuild my master cylinder and I'm  a little confused about part compatibility.  I see a lot of kits for the 74-76 but not a lot of for the 77-78's.  Some listings show 74-76k and 77F together, but when I look up part numbers, the 77F is the same parts as the 77-78K.

  Is this a mistake by the seller?  would the 74-76K kits work with the 78K?  It seems as though any listings for the 77-78k is much more expensive than earlier models.

  Any help is appreciated.

Thanks

[eastyork1977]

most of the CB master cylinders were pretty much the same up until '76. Up until then 750 and 550 m/c had the same internals.

The 750F models in '77 up have a larger master cylinder for the dual brake system. Therefore that piston inside the cylinder shaft is larger as well so you've got two different kits available.

If its a dual disc, you'll need the larger piston kit for that over sized cylinder.
If its a single disc, the smaller kit will work. (45530-404-315 for 550).

[Farley121]

Thanks Eastyork

[eastyork1977]

If you need the larger master kit, I've got a K&L set at the shop.

Cheers