Vacuum petcock not functioning?

[mrhedges]

On the highway last week on my way to visit a friend the bike died. It was unresponsive at quarter throttle then it just died. I could tell by looking at the inline filter that it wasn't getting gas. I put it on prime and ran fine. Back home I replaced the vacuum line which seemed a bit dry, and I wanted to replace anyway because it seems a bit to short making putting the tank back on a pain.

The bike sits up a bit because I decide to bleed the brakes and I strip out a bolt in the master cylinder (which probably had never been off) . I order a new one, install it bleed the brakes. Ride the bike over a mile and start having the same issue. The bike is unresponsive at quarter throttle. I get home put it on prime and the fuel flows again. I go in my house for a sec to get ready for work, leaving the bike on prime come back out and notice a gas leak. At first I think maybe my floats are bad but the leak seems to be coming from the petcock. Would a leaking petcock cause the an issue with fuel delivery when the petcock is set to ON? With the petcock set to prime the bike runs great, starts easily, throttle response is good and it idles and never dies even when cold. The carbs have been cleaned and orings replaced recently.

Should I just go ahead an order a new Petcock? Is there some way to test the vacuum feature on the petcock so I can be sure this is the issue?

[Rust_to_Redemption]

So you had a gas leak from the petcock when it is set to prime? Am I understanding that correctly? If so, if gas can get out, air can get in. I assume that would hinder the vacuum operated nature of the petcock when in the "ON" position.

[mrhedges]

Yes, it leaks a bit when set to prime. But not right away, it takes a while

[tom203]

"Should I just go ahead an order a new Petcock?"

yes

[mrhedges]

"Should I just go ahead an order a new Petcock?"

yes

cool, so someone recommended Z1 aftermarket petcocks but I only see ones listed for the L model of my bike. I need Part # 44300-45011 should I just order the OEM one for $95 ? I found one on ebay for $30 that might be ok, does anyone have any experience with after market vacuum petcocks? not really interested in the pingle ones If I'm gonna spend the money i'd go with OEM.

[hannibal]

Where is it leaking from?

[Grimly]

cool, so someone recommended Z1 aftermarket petcocks but I only see ones listed for the L model of my bike. I need Part # 44300-45011 should I just order the OEM one for $95 ? I found one on ebay for $30 that might be ok, does anyone have any experience with after market vacuum petcocks? not really interested in the pingle ones If I'm gonna spend the money i'd go with OEM.

Gorminrider and myself tried the el-cheapo aftermarket petcocks a couple of months ago and we weren't impressed.
Superficially, they seem ok, even quite well-made, but they fall down on the details inside.

https://www.thegsresources.com/_forum/showthread.php?254803-Cheap-petcock-for-GS850s&p=2533941#post2533941

https://www.thegsresources.com/_forum/showthread.php?254803-Cheap-petcock-for-GS850s&p=2534481#post2534481

[mrhedges]

it drips every so slightly out of the handle it seems

[mrhedges]

Gorminrider and myself tried the el-cheapo aftermarket petcocks a couple of months ago and we weren't impressed.
Superficially, they seem ok, even quite well-made, but they fall down on the details inside.

https://www.thegsresources.com/_forum/showthread.php?254803-Cheap-petcock-for-GS850s&p=2533941#post2533941

https://www.thegsresources.com/_foru...81#post2534481

That's good to know, I went ahead and ordered the OEM one for $94. I'm planning a big trip and would rather it not crap out on me. Thanks for sharing

[HiSPL]

Seems like you already ordered one, but here is my solution from a long time ago. Several people did this mod to the stock petcock and had much success.

https://www.thegsresources.com/_forum/showthread.php?78551-Vaccum-petcock-convert-without-replacing&p=300816#post300816

[mrhedges]

Seems like you already ordered one, but here is my solution from a long time ago. Several people did this mod to the stock petcock and had much success.

https://www.thegsresources.com/_foru...816#post300816

Thanks for sharing this is useful

[mrhedges]

Hello, I wanted to post a pic of how I currently have the fuel line ran to see if I did it right:

[Grimly]

There will be some who say - "You don't need the filter, junk it."
My view is; having been stuck broken down because of junk in the tank that blocked up the tiny little filters in the entrance to the carbs, I've fitted a filter to every bike since and that episode has never repeated. I'd rather replace the external filter once in a while (and I keep a visual on it every so often, as it discolours through doing its job) than be stuck like that again. Hell, even if it does block up on the road, you can either find another one locally or run without it for a while - although if it's just started to block there might be a lot more crud in the tank to come out yet.
Just make sure the filter is big enough to flow what your engine needs; many of them sold for bike use are too small.

[Gorminrider]

(PS to Grimly...in case you return to this petcock someday, untested yet but I put a spring from an old stock petcock in WITH the existing one-it is larger diameter. The smaller one holds it in place... this might make our cheapie-but-decent petcocks useful someday. I wonder if the wimpy springs suit a weaker fuel pressure..perhaps from bikes that use a vacuum fuel pump??? ...)