Master Cylinder sight glass rebuild? 1982 GS650GLX

[orangechicken007]

Well after 42 years the sight glass on the master cylinder finally gave out. It's been cloudy the entire time Ive owned the bike but it never gave me any issues leaking from the sightglass (or leaking period once I replaced the internals). Then when I went to pull it out for spring I noticed no brake pressure and after a little investigating I ran my finger over the sight glass and a piece broke off lol.
Ive seen some people have luck replacing the sight glass, but those are the master cylinders with the 18 mm sight glass and but I have the 22 mm sightglass with the metal rim around the edge. So my question is, is it worth trying to rebuild (jb weld a piece of lexan?) or should go ahead and buy a new aftermarket one? There are dozens of cheap aftermarket master cylinders but I don't really want to skimp on brakes.

 

[Nessism]

EX650 master. Look for the rectangular reservior type. They are 5/8 bore, so good for bikes with dual discs. Commonly available in good condition for $30 shipped or so off eBay. Here is one such example...

https://www.ebay.com/itm/134813243452

And don't forget to replace your rubber brake lines, if you are still using the originals. They are sure to be crusty and full of grunge inside after 42 years.

 

[Cipher]

Well after 42 years the sight glass on the master cylinder finally gave out. It's been cloudy the entire time Ive owned the bike but it never gave me any issues leaking from the sightglass (or leaking period once I replaced the internals). Then when I went to pull it out for spring I noticed no brake pressure and after a little investigating I ran my finger over the sight glass and a piece broke off lol.
Ive seen some people have luck replacing the sight glass, but those are the master cylinders with the 18 mm sight glass and but I have the 22 mm sightglass with the metal rim around the edge. So my question is, is it worth trying to rebuild (jb weld a piece of lexan?) or should go ahead and buy a new aftermarket one? There are dozens of cheap aftermarket master cylinders but I don't really want to skimp on brakes.

Amazon has replacements. They work fine.
https://www.amazon.co.uk/s?k=motorc...ycle+sight,aps,230&ref=nb_sb_ss_ts-doa-p_1_16

 

[Datsa Noydb]

I have seen several reports of cutting/filing a disk of Lexan plastic, then using epoxy to set it in place. Seems to work well enough.

 

[orangechicken007]

Hey guys thanks for the responses. I thought Id show you what ended up working in case someone had a similar master cylinder. I gently pried out the metal ring and what was left of the sight glass. Inside the metal ring was a big rubber O ring holding everything in place. The original sight-glass was around 15 or 16 mm hard to tell because It was tapered slightly. I took a 18 mm sight glass and carefully sanded down the outside diameter until it was close to the original size, about 16mm. The fit for the new sight glass was tight and but once it was in it felt secure. I cleaned the corrosion out of the hole in master cylinder and then tapped the new sight glass assembly with a rubber mallet. So far its working great no leaks after bleeding the brakes and several rides.