Help, I rebuilt the Front Master Cylinder

[Burk Ferden]

Hello everyone,

I have a problem and would love the help. I rebuilt the front master cylinder and now it wont pull fluid. I pump the leaver but it doesn't pull the fluid, I think I might have the master cylinder piston in incorrectly. I don't know where the rubber peices go.

Thanks!

Justin

[Nessism]

To prime the master open the bleeder on the caliper and place a piece of tubing on the nipple like you are going to bleed it. Now suck on the line - making sure you don't suck fluid into your mouth of course. As you draw a vacuum the fluid in the reservior will be drawn down priming the master.

Good luck.

[Burk Ferden]

Wow didn't try that

To prime the master open the bleeder on the caliper and place a piece of tubing on the nipple like you are going to bleed it. Now suck on the line - making sure you don't suck fluid into your mouth of course. As you draw a vacuum the fluid in the reservior will be drawn down priming the master.

Good luck.

I thought I put it together wrong because the fluid would slowly leak out the back where the leaver pushes the piston. Its a 1980 gs850.

[Wire Wheel Katman]

I thought I put it together wrong because the fluid would slowly leak out the back where the leaver pushes the piston. Its a 1980 gs850.

Sounds like you have at least one of the seals in the wrong way around. The wider end of the seal goes in the cylinder first.

[Nessism]

Yup, sounds like you put it together wrong - you didn't mention the leak in your first post.

Regardless of that, priming the master is a common issue on GS master cylinders - the vacuum trick works well.

[Burk Ferden]

Or I am missing one. There is a rubber seal I didn't put back in. I thought it was for the circular master cylinders. I have the product pictured below. The way i put it in the cylinder is. Spring, large round seal, piston then the circlip then the rubber boot. What I notice is that the front of the Piston and the large rubber seal are past the intake hole from the reservoir so there would have to be a seal in the back. I don't know. This sucks

[Burk Ferden]

Does anyone have an exploded view of the rebuild kit in the order it would go together. The fiche doesn't really help.

[catbed]

go on basscliff's website and download the 850 shop manual. they tell you how to take it apart and put it back together.

[Burk Ferden]

seems to be down. I guess I'll try sending him a pm

[Burk Ferden]

I have the clymer manual but it doesn't show the exploded view of the front master cylinder, just the brake calipers.

[Burk Ferden]

So at this point I think I would like to just put a new front master cylinder on the bike since I got new Low bars. Would anything with a 13mm Piston work for my 1980 GS 850G? I could just find like a GSXR front master cylinder?

[duaneage]

I bought a Magura generic master cylinder for my GS, actually I ordered it. When it came in I was disappointed it had a plastic body. It's suppposed to be a good unit but I don't care for it.

It's brand new and I paid 90 dollars for it. If you don't mind the plastic you can have it for 30 dollars plus shipping. PM me if interested.,