While dealing with my weeping oil (turns out to be the clutch cover gasket), I tried to start the bike. Bike spewed some gas out the overflow tube so I'm thinking a stuck float valve. After pulling the very full gas tank off, removing the carb and pulling the float cover off, I find that it's clean and works normal. So I test the vacumm pistons and sure enough, #2 is torn, in 2 spots parallel to each other (one tear is 1/4" and the other is 1/3"). Other than spending the $100+ to get a new 1 or spending about $60 for a whole rack with pistons that would fit, does anybody know of any glue that would work?

 

I'm thinking that the type of glue to hold that would mean doing some kind of patch, kind of like you do when you repair an inner tube from a tire. The problem then becomes making sure that it is still flexible enough to allow the Vacuum Piston to move freely up and down as it needs to. That's a tough challenge. I think I'd look for a set off ebay that you could barrow from. It looks like, according to the parts manuals that the '93 - '97 900RR uses the same Vacuum Piston. At least that opens up the search a little.

 

I always thought for these diaphrams to used the hondbond and empregnate a thin cloth as a patch. I do think though since you are working with 4 pistons that need to rise and fall at precisly the same rate patching probably would not work as well as it could.
My 02 cent worth.
honda bond is used for a gasket material but is very durable and remains very flexable.

Big smoooth

 

Anybody think a thin coat of RTV silicone might work?

 

I don't know..., silicone (like caulking) seems to be good in sealing things, but i'm not too sure how well it would adhere to the rubber material. Also with the continious flexing I think sooner or later it would fail. Naturally it would be at the farthest point from home.[&:]

 

The only other thing that pops into my head would be rubber cement (like used in repairing car tires)

 

A friend of mine used a small section of Duct Tape. Worked fine until he could afford new diaphragms. Not perfect, but effective short term......