When replacing diapragm, where she the petcock be turned to?

[Guest]

Im replacing the diaphragm in my petcock today on my 80 GS1000 and I dont know what direction the petcock valve thing is turned to. How do I know which direction its at and when replacing the diaphragm, where should it be turned to?

[chuck hahn]

leave it in the run position and as you take the two halves apart note where the hole in the diaphram is sitting and insert the diaphram the same way and reassemble. thats how i do it anyway. And some people suggest giving the spring a slight stretch to asure it applies enough pressure to seal good when the vaccum isnt there..

[sedelen]

I had two leaky petcocks, one leaked externally (around the selector lever) and the other leaked internally, (would'nt completely shut off the fuel in run or prime). I fixed the one that leaked externally with a new O ring from a kit. The other one I failed to fix by replacing the diaphram, still won't shut off the fuel. Chuck I'm gonna tear that one apart again, check the mating surfaces, and try what you did, "strectch" that spring a little
and see if that does the trick, otherwise I feel it's just bad internally and then I have to try to locate another one. Can't seem to locate a new aftermarket one anywhere for a '78-'79 GS1000 and I'm not going to pay
$200+ for a new one from Suzuki.

[TooManyToys]

Stretching a spring is really not a good idea. The spring height has lessened due to metal fatigue and stretching it in the opposite direction just fatigues it more, which will cause it to shorten more during use worsening the condition.

The ideal is shim it so the tension is correct given its installed height. One of two problems is we don't have that spec, and the second for me is I've never disassembled one of these petcocks to see how to shim the spring.

[bonanzadave]

The ideal is shim it so the tension is correct given its installed height.

Couldnt a guy buy a new spring from the same place he gets a new diaphram ?

[sedelen]

Stretching a spring is really not a good idea. The spring height has lessened due to metal fatigue and stretching it in the opposite direction just fatigues it more, which will cause it to shorten more during use worsening the condition.

The ideal is shim it so the tension is correct given its installed height. One of two problems is we don't have that spec, and the second for me is I've never disassembled one of these petcocks to see how to shim the spring.

Stretching the spring is almost a last resort to tossing the petcock away. A longer spring would certainly add more pressure to the little O ring on the diaphram to help seal it. I would measure it first and only increase it say by 10% or so. Before I do that I would check the mating surfaces to see if there is dirt or something not allowing it to close all the way and seal properly. Because of the design of the diaphram any shim would not be secured and if you could it would cause other problems with the diaphram. Another last resort would be to remove the tab on the selector cover allowing the selector switch to be turned up (opposite the run position), this would shut off the fuel, but you would have to remember to do that everytime you shut the bike down. Unfortunately the kits don't come with springs. To top it all off I haven't been able to find a aftermarket petcock for a '78-79 GS1000 and Suzuki wants $200+