GS750 master cylinder parts availability

[mattd1205]

I’m rebuilding my front MC on my 1978 GS750C with single front disc. I apparently ordered the wrong OEM rebuild kit and found out I need the 59600-45821 instead of the 59600-33811 that the parts fiche specifies. I was reading on here that the ‘77 Gs750 MC used a diffent Kit than the later models.I also noticed the oring between the reservoir and the MC is wrong too. The oring (59686-33620) i ordered is thinner than the one I pulled from the MC. Does anybody happen to know what the proper o-ring part number is?

thanks
Matt

[mattd1205]

For reference for anybody who finds this in the future: apparently Suzuki used two master cylinder manufacturers (Asco and Nissin for the single disc models. The parts fiche makes no acknowledgment of this. They are both 14mm master cylinders. The main identifier in identifying Nissin vs Asco is the reservoir. The Nissin has 5 holes at the bottom of the cup while the Asco has 2 holes and an elongated passage at the bottom that runs the width of the cup. The Asco requires the 59600-33811 piston and cup set with the 59686-33620 oring for the resovoir. The Nissin has the 59600–45821 piston and cup set with the 59686-33600 oring.

[Gorminrider]

Thanks! I'll save this.

[Justin]

Thank you for updating this after the fact!