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1983 GS850GL - Fuel Petcock return spring for vacuum operated diaphragm?

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Hello GS forums, this is my first post.

I am the new (to me) owner of a 1983 GS850 GL that had ~6000 original miles on it. I was sick of the cheap bike I had ($600 Kawasaki KZ750) and decided to spend a little more on a low mileage bike. It starts right up, but as old bikes go it has a couple issues.

The issue I will bring up in this post is in regards to the fuel petcock. In other vacuum operated petcocks I've seen there is a return spring for the diaphragm that allows fuel in. The spring holds it closed until the vacuum from the carbs opens it to allow more fuel.

However, when I look at parts websites such as Rocky Mountain ATV, they only blow up the front half of the petcock.

Fuel.jpg

Anyone have any idea what size the spring is or where I can buy a replacement without buying a whole petcock assembly?

Or better question, is it supposed to even have a spring?
 
I'm nosey, What's the problem? pet cock not shutting fuel off? lost spring? weak spring? Ebay, Suzuki pet cock rebuild kit. should be around $10.00. Some come with spring, some don't show a spring in pictures . Did you lose yours? they're made of very fine wire & hard to find when dropped. Oh yeah, Welcome.
 
rphillips said:
I'm nosey, What's the problem? pet cock not shutting fuel off? lost spring? weak spring? Ebay, Suzuki pet cock rebuild kit. should be around $10.00. Some come with spring, some don't show a spring in pictures . Did you lose yours? they're made of very fine wire & hard to find when dropped. Oh yeah, Welcome.
Click to expand...

Hello. Yes, I should have clarified, the fuel does not shut off when the bike is not running. I took it apart and found there was no spring behind the diaphragm. If there was supposed to be a spring, the previous owner I bought it from must have lost it because I had never taken it apart before.

Thank you for link and thank you for the welcome!
 
I just looked up the repair kit for a n "83" GS850GL, on Ebay. Looks like you would need, in the K&L brand, part # 18-4344. The pictures of that kit do not show a spring. I've not worked on your particular model petcock, but all the Suzuki pet cocks I've worked on had a spring, & I can't imagine how it could work without one. Sorry, I have no answers.
 
rphillips said:
I just looked up the repair kit for a n "83" GS850GL, on Ebay. Looks like you would need, in the K&L brand, part # 18-4344. The pictures of that kit do not show a spring. I've not worked on your particular model petcock, but all the Suzuki pet cocks I've worked on had a spring, & I can't imagine how it could work without one. Sorry, I have no answers.
Click to expand...

Thanks for doing the leg work for me! I'll order one up and try it out.
 
Save your money and time; the petcock rebuild kits are useless.

This has been proven over and over and over and over and OVER again, and it's one of the top newbie mistakes.

Install a replacement petcock and worry about something else for the next 20-30 years. It's well worth the modest investment. The OEM petcock is around $70, or there are some reputable suppliers such as Cycle Recycle II or Z1 Enterprises.


This is a valve that controls the flow of a incredibly flammable, highly explosive substance a few inches from your crotch. Even if rebuild kits worked more than rarely, it's really not worth messing around here.
 
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If there was supposed to be a spring
Click to expand...

Sadly, I don't think any rebuild kits come with a spring. AND it's required for the vacuum petcock to function and, it must be the correct spring to resist a full tank's fuel pressure and still be "overcome" by the engine's manifold vacuum... (I mean to measure the gauge of wire used for the springs someday...)

The o-ring on the plunger is also crucial....
 
Amazing how simple these things are. If you have a clean smooth seat for the "O" ring to seal against, a proper fitting "O" ring on the plunger, & the proper spring pressure & tension, there is no reason for the pet cock not to seal off the fuel, till vacuum is applied. Either 2 or 3 winters ago, my "05" Bandit 12 leaked a bunch of gas into the crankcase, over the winter. Not wanting to remove the carbs. & find & fix a leaking needle & seat, I took the pet cock apart & inspected everything. Saw nothing on seat, polished it good with a pencil eraser, "O" ring looked fine, no burrs, cracks, nor rough spots, & stretched the spring appx. 3/8", & luckily no problems since. Wish I could help with finding a spring. Good luck
 
I rebuilt a petcock a few years ago with genuine OEM Zuk parts, but only the multi-holed front rubber plate and small o-ring were available.
I faced the inside of the lever casting with 1000 grit wet'n dry, cleaned it all up and crossed my fingers.
It worked.
I don't know how long it would have worked, as it was on the other tank, and I'm not using that right now.
 
mean to measure the gauge of wire used for the springs someday...
Click to expand...

and so I did on a couple of petcocks...

Length of spring 1.83cm
Diameter of spring 0.92 cm
Turns 6
Wire spring wire diameter 0.5mm ..not exact as using the vernier scale on my calipers to measure..but as measured 0.6 mm springs I have are definitely too thick.

I have a wire gauge too but forgot to note it.

Some variety of guitar string (dulcimer, mandolin?) should do to wind one
 
Just get a new replacement from Z1 Enterprises -- change it and go on with your day ;)

That's what I did a couple of years ago and no trouble ever since
 
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