petcock nightmares

[94ta]

BassCliff, yes thanks for reminding me of that post.

The petcock that has the mounting points too far away is measureing out to be in the 48-50mm range. The one i have/need is probably a 44mm.

I rearrange the way it was put together, I put the spring in the barrel.. Now when i blow through the vac line, i cant, but with the petcock installed on the tank and the lever in PRI/RES/ON fuel still flows out very very quickly in any position, nothing is restricting it in any position.

I was under the impression that with these vaccum style petcocks the carbs gets different amounts of fuel at idle then it would when revving. This is why i think the carbs are dumping fuel at idle. In the past with the petcock befor it was rebuilt it would dump fuel while idling and while not running. I dont want to make the house smell like gasoline another night but i dont think this "rebuild kit" cured anything and most likly wasted 40$.

The floats being stuck is a possibility, I havent taken these carbs apart yet since i was told they came off a running bike and didnt sit long at all, They probably do need a good cleaning, I dont really want to dive into that untill i get this petcock figured out.

[sedelen]

So.......... before I go any further here, is that the same petcock as the one on page 18 of the owners manual in from the link in my previous post?
And what model GS1000 do you have?

[Bakes]

Yes, the vacuum petcock with the 44mm (approx 1 3/4") bolt-spacing should work on your '79 GS1000.

NO - you shouldn't be able to blow thru a petcock that's not in the PRI position.

However - if fuel is dumping from #2, it's indicative of a float valve (needle & seat) failure.

Not returning to idle typically implies an air leak of sorts. Pod filters and stock jetting shouldn't influence this.

Don't get discouraged - eat that elephant one bite at a time.

[sedelen]

There is a check valve inside the petcock for the vacuum line. You should be able to determine if it works by sucking and blowing air through it. All bets are off if you can blow air freely both ways.
I've had some success rebuilding these petcocks. You have to align the holes on the diaphram, to the hole in the block that fits between the two sides of the diaphram, to the breather hole on the main part of the petcock that goes to the front of the diaphram. I learned through trial and error, but the one thing I was overlooking because it's hard to see is that hole on the petcock, it's about in the 2 o'clock position as you look at the front of the petcock, close to the upper right hand mounting plate that attaches to the back plate, close to one of the 4 back plate mounting screws. If that hole is clogged your petcock will not breathe and allow your diaphram to open and close normally.
Also that 4 hole rubber seal under the selector lever has got to be good, as does the seat the little O ring mates to on the diaphram. Your vacuum line should be in about the 10 o'clock position as you look at the front of the petcock. Any little dirt can cause it to fail, I soaked mine in gasoline and put it together loosely, to allow the diaphram to find it's own center and tightened down the screws evenly.
The carbs flooding to me is normal if the bike sits and has gas going to the carbs. Both my bikes have done it when I left it in Prime, and it is clearly stated in the owners manual that can happen.

Also, there is an old post I have been trying to find that I have not been able to locate. It concerns a "modification" to the petcock that will not allow fuel to flow, but you can't forget to not turn it off. I didn't want to suggest that yet for fear of taking responsibility for it should that fail, so I'm still looking for that post.

[rustybronco]

Also that 4 hole rubber seal under the selector lever has got to be good, as does the seat the little O ring mates to on the diaphram.

And that's all the parts mine needed.

[BigD_83]

There is a check valve inside the petcock for the vacuum line. You should be able to determine if it works by sucking and blowing air through it. All bets are off if you can blow air freely both ways.
I've had some success rebuilding these petcocks. You have to align the holes on the diaphram, to the hole in the block that fits between the two sides of the diaphram, to the breather hole on the main part of the petcock that goes to the front of the diaphram. I learned through trial and error, but the one thing I was overlooking because it's hard to see is that hole on the petcock, it's about in the 2 o'clock position as you look at the front of the petcock, close to the upper right hand mounting plate that attaches to the back plate, close to one of the 4 back plate mounting screws. If that hole is clogged your petcock will not breathe and allow your diaphram to open and close normally.
Also that 4 hole rubber seal under the selector lever has got to be good, as does the seat the little O ring mates to on the diaphram. Your vacuum line should be in about the 10 o'clock position as you look at the front of the petcock. Any little dirt can cause it to fail, I soaked mine in gasoline and put it together loosely, to allow the diaphram to find it's own center and tightened down the screws evenly.
The carbs flooding to me is normal if the bike sits and has gas going to the carbs. Both my bikes have done it when I left it in Prime, and it is clearly stated in the owners manual that can happen.

Also, there is an old post I have been trying to find that I have not been able to locate. It concerns a "modification" to the petcock that will not allow fuel to flow, but you can't forget to not turn it off. I didn't want to suggest that yet for fear of taking responsibility for it should that fail, so I'm still looking for that post.

Is this the mod you are talking about?

http://www.thegsresources.com/_forum/showthread.php?t=130786&highlight=petcock+modification

[sedelen]

Is this the mod you are talking about?

http://www.thegsresources.com/_forum...k+modification

No, but here it goes, and I'm not suggesting anyone do this, as I'm recalling it from memory of something I read about a year ago.

First, you file off the stop on the front piece that keeps the lever from rotating completely around, then you file off enough of the lever so that the lever can point straight up without hitting the gas tank. When the lever points up, fuel is shut off, that's it in a nut shell. But I'd like to find that post to see if there's any more details other than that.

[BigD_83]

No, but here it goes, and I'm not suggesting anyone do this, as I'm recalling it from memory of something I read about a year ago.

First, you file off the stop on the front piece that keeps the lever from rotating completely around, then you file off enough of the lever so that the lever can point straight up without hitting the gas tank. When the lever points up, fuel is shut off, that's it in a nut shell. But I'd like to find that post to see if there's any more details other than that.

Here's a thread with pictures of that mod...

http://www.thegsresources.com/_forum/showthread.php?t=167714&highlight=file+fuel+petcock

[sedelen]

Here's a thread with pictures of that mod...

http://www.thegsresources.com/_forum...e+fuel+petcock

You be the man! That's the thread, last November, knew it was about a year ago, I even posted in there. Thanks! No doubt this is a "last ditch"
effort for a petcock repair.

[chirobo]

Your bike is an inanimate object. If things are right it will run right. You must take your time, be methodical and follow the checklist on BassCliff's site. Buying a petcock which does not fit is not the bike fault. The carbs you bought on ebay must be checked thoroughly - they may have all sorts of problems. There are no short cuts. Sorry but this is the only path to success.

This is my favorite post of any I've seen, especially the inanimate comment...classic. I have actually been quoting this post to explain to my patients how to improve their spines (I'm a chiro). The spine is sort of inanimate and will improve if you do things in the correct order, exactly as I tell you to do...nearly every time, just like a GS will respond to the executed list of "things to do". I get such a kick out of reading DAILY of the malfunctioning GS and all of it's woes (that are this "stupid bikes" fault). And then I wait for it...wait for it..BassCliff and Co. do their thing, and if advice is meticulously followed...the universe falls into harmony again...if they do not the GS gremlins attack at will...squirting gas into eyes, and emptying cans of seafoam into the abyss as valves overheat and are sucked in!! I mean to compliment all of you on your patience pertaining to the redundancy and repetitiveness of this service that you provide for no remuneration except for the love of machinery and your fellow man. I am in awe!! Thank you all.

[sedelen]

This is my favorite post of any I've seen, especially the inanimate comment...classic. I have actually been quoting this post to explain to my patients how to improve their spines (I'm a chiro). The spine is sort of inanimate and will improve if you do things in the correct order, exactly as I tell you to do...nearly every time, just like a GS will respond to the executed list of "things to do". I get such a kick out of reading DAILY of the malfunctioning GS and all of it's woes (that are this "stupid bikes" fault). And then I wait for it...wait for it..BassCliff and Co. do their thing, and if advice is meticulously followed...the universe falls into harmony again...if they do not the GS gremlins attack at will...squirting gas into eyes, and emptying cans of seafoam into the abyss as valves overheat and are sucked in!! I mean to compliment all of you on your patience pertaining to the redundancy and repetitiveness of this service that you provide for no remuneration except for the love of machinery and your fellow man. I am in awe!! Thank you all.

Well, I'm certainly glad someone got something worthwhile out of this post!

[BigD_83]

I wish my electrical skills matched the speed of my search skills in this forum

[allojohn]

Yeah, come on 94ta, where are you on this?

[94ta]

I got busy with work and moving. Havent had a free moment to put into the bike, and any free time ive had its been 110* outside.

I did measure the bolt holes of the petcock, 44mm is what it is. Thanks for the replys and your time. Sorry i didnt get a picture of it, but it hasnt looked like any of the ones ive seen so far.

Just bought one for 44$ on ebay. I guess the tank i have isnt a stock 79 tank as the 44mm spacing is more common on early to mid 80's bikes?

[94ta]

Well heres a picture of the old petcock, just because i finally found a camera. I went through the carbs, wow. One of the main jets was literallya half turn away from falling out, blocked beyond all hell. Ill be doing the soak it looks like! The idle jets are rough too, suprised it even ran. Thanks for all your help as always.

Also here are pics of my intake boots...theres no oring on these, what does this mean?