Brake fluid reservoir viewing window leaks

[alph]

I’ve got an old Yamaha cycle that I’ve been working on and the front brake reservoir window leaks brake fluid.  I covered it with silicone, but now I can’t check the fluid level.  So, I scrapped off the silicone, only to find that the plastic viewing window has a hole in it!  The plastic its self is brittle. 

So, has anyone ever replaced one of these plastic windows?  I’m temped to make one out of a piece of Plexiglas since I can not find one online or at the local cycle shops.  When I ask the service counter guy if he’s ever done anything like that, he says he hasn’t.

Anyone have any suggestions?

[Michvalk]

There are probably several bikes that use the same sight glass. Maybe look at different models and find one close, and cut it down. Might find a complete unit at a bike junkyard.

[97Valk_CT_Euless]

I doubt the window was ever intended to be replaced. Whatver you use you'll want to test for a few weeks in brake fluid to make sure it doesn't fog or deteriorate.  That's pretty mean stuff.  Will be hard to seal also.

Though of pouring it with a clear epoxy?  West Systems may work, but I'd test it first.

[04strider]

This is a common problem with older bikes, and the suggested solution is to replace the plastic lens with a watch crystal of the same size.  Remove the existing plastic window, and find a replacement watch crystal of similar size and epoxy it in the recessed hole.

[alph]

This is a common problem with older bikes, and the suggested solution is to replace the plastic lens with a watch crystal of the same size.  Remove the existing plastic window, and find a replacement watch crystal of similar size and epoxy it in the recessed hole.

that's a good idea!  thanks.

[R J]

My old Yama-hopper the glass leaked, we messed with it for about 6 months and one day I just stuck a dime in the hole and epoxyied it shut.

Every month or so, I'd pull the cap off and check for dark color or low.

Worked for  the last 4 years I had the bike.