Rebuild 1979 gs 850 petcock

Thanks for the link Gorminrider will check it out

[Gorminrider]

There's a cheapie on ebay that seems to work. $27.99 I even bought one! and it seems good so far. The lever is longer and easier to turn too. You'l want to double check the outlet is on the right side ..but the vacuum inlet can be rotated by undoing at the back if need be. But I found it fit fine on my 81GSX400T
amazon.ca
https://www.amazon.ca/dp/B07GSXY9PD/..._rv_eml_rv0_dp
ebay cheap petcock.jpg

Place strong spring to shut the diaphram in closed position with vacuum blanked off and use "prime' as 'on' and 'ON' as off

Yes I can see where that would be a fix of sorts but then I have no "reserve" function and having 4 bikes my addled old noggin doesn't need anymore confusion. I find it confusing enough just using the standard setup with no OFF other than lack of vacuum! I

Well it looks like my "fixed" oem petcock is now screwed up again. When I disconnected the fuel line the fuel pours out of the tank so the vacuum shutoff no longer works. I see where somebody had recommended https://www.georgefixs.com/new-suzuk...s1150-petcock/ He lists one made in Japan for about half the price of an oem fuel cock. I have sent him 2 messages but no reply. Anyone here that has dealt with him recently?

Place strong spring to shut the diaphram in closed position with vacuum blanked off and use "prime' as 'on' and 'ON' as off

Well it looks like my "fixed" oem petcock is now screwed up again. When I disconnected the fuel line the fuel pours out of the tank so the vacuum shutoff no longer works. I see where somebody had recommended https://www.georgefixs.com/new-suzuk...s1150-petcock/ He lists one made in Japan for about half the price of an oem fuel cock. I have sent him 2 messages but no reply. Anyone here that has dealt with him recently?

I've never had luck greasing petcocks and I've tried several types of grease MAINLY because the gasoline fumes attack them I think...and between any two sliding surfaces the fumes can't go, neither can the grease -it gets squeezed out. I even think Some greases will swell the viton-or-nitrile rubber or the nylon "selector" inside and make it worse but that's just a feeling.But yours may "wear in" and be ok.

Yes I was wondering how long the grease would last.I will leave well enough alone. Just a little stiff to turn the selector lever right now.

[Gorminrider]

I've never had luck greasing petcocks and I've tried several types of grease MAINLY because the gasoline fumes attack them I think...and between any two sliding surfaces the fumes can't go, neither can the grease -it gets squeezed out. I even think Some greases will swell the viton-or-nitrile rubber or the nylon "selector" inside and make it worse but that's just a feeling.

Naturally, applies to carbs too. You can put a drop of oil on shafts and cables but nothing inside.
I've even fiddled with thespring clip (on-off-prime printed) that holds the tap-and-selector. The little tabs that hold the clip, but it's risky.
Some petcocks I have are just really tight and hard to turn, especially with gloves. I mean to give up lubrication and just make the handle longer

But yours may "wear in" and be ok.

BTW does anyone use a smear of brake grease in the petcock to lube the selector & four hole gasket? Just wondering as the new setup is quite a bit stiffer to operate. Could be a good thing I guess but thinking it may wear faster.
Jonesz

My new petcock gaskets showed up so today I took it apart again and put in a new "4 hole gasket". and a new round gasket that seals the selector switch. Only thing beyond that was took Grimly's advice and cleaned up the inner plate on the selector with 1000 then 2000 grit paper on a sheet of glass to keep it flat. Buttoned it back up. threw in some gas and NO DRIPS and when primer was selected the gas poured out as it should. Looks like I got the old one fixed for 13 bucks instead of over 140 Cdn. Fingers crossed, the petcock really had only a little over 10,000 actual miles on it and nothing seems loose or worn other than the 4 hole gasket. Thanks all for the advice.

[superawesome]

I successfully rebuilt mine with a "Tourmax" kit from ebay and it's been working for three years now. Picture shows how much the old washer shrunk in 40 years, no wonder it leaked...
WP_20171020_14_56_36_Pro.resized.jpg

[rphillips]

I'd think the rubber diaphragm + vacuum will control the opening of the valve, the spring, "O" ring, & seat will control the closing & sealing of the valve. Hoping for the best in both directions, good luck.

I had success rebuilding one of mine, but the main reason it failed was the holed rubber sheet had stuck and torn slightly around the holes, so when I replaced that I buffed the mating surfaces inside, to make sure it would take longer to stick and catch. I rubbed the surfaces with 1000-grade emery cloth and polished them with T-cut. If any of the other parts had failed, I'm not sure the rebuild would have been any good, as seems to be the common complaint with the kits.
Also, I used OEM Suzuki parts - I've got no faith at all in the aftermarket rebuild kits.

That appears to be the problem with my petcock. Visually it looks like the rubber with 4 holes has been worn/torn at couple of hole edges. I ordered oem parts and will take your advice on cleaning up the surfaces with 1000 or 2000 grit. Not much to lose in trying other than $20.

[Grimly]

I had success rebuilding one of mine, but the main reason it failed was the holed rubber sheet had stuck and torn slightly around the holes, so when I replaced that I buffed the mating surfaces inside, to make sure it would take longer to stick and catch. I rubbed the surfaces with 1000-grade emery cloth and polished them with T-cut. If any of the other parts had failed, I'm not sure the rebuild would have been any good, as seems to be the common complaint with the kits.
Also, I used OEM Suzuki parts - I've got no faith at all in the aftermarket rebuild kits.

Tried to order an OEM petcock but they are on back order so the dealer ordered me new gaskets and I am going to rebuild the one on my 79 gs850 with only 17,000 kms on it (just over 10,000 miles). Will let you know how it works out when the parts arrive. BTW up here on the Canadian prairies a new oem petcock is $143 Cdn. including tax or approx. 110 US $!!

...the tiny o-rings on the plunger seal are crucial,IMO... In operation, the plunger wiggles in and out per the vacuum applied from the engine...If the diaphragm seems to be ok , I'd go straight to cleaning the bore out and looking for just the tiny o-ring at the hardware store...I'm not sure "rebuild kits" get this right especially as there's bound to be a teeny bit of wear on the alloy bore too.

Will check that as well. Thanx