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78 GS1000 petcock info/advice

  • Thread starter Thread starter pitbullmccoy
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pitbullmccoy

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My petcock works good off the vacuum but leaks a steady stream even when the hose is pulled off. This results in one of my Carb (#3 I think) overflowing. I know I need to get that issue straight but I want to fix the petcovk first as I'm sure it will help if not solve that problem. My question being what's the difference between my '78 and '80's model petcocks. After countless searches I've only managed to find one replacement for the '78 @$300 and some change. Which to me is obscene when I can find an abundance of them for '80 and beyond for around $50. I'm sure some of these have to run off vacuum . The only issue I see is bolt spacing which I will measure when i get home from work today. Just for the record I've tried the search option, read several threads and come up with nothing. And ill have to go back and double check but I'm pretty sure the part# is 44300-44011. Any and all info is GREATLY APPRECIATED! if you have an '80's model the does indeed run off vacuum I'd like to know.
 
Measure that centerline bolt spacing. Lots of new petcocks available under $100, some as low as $45 (like mine!). You do not want the 1980 petcock-it has unique features, to be avoided if possible.
 
I read somewhere on here not to waste time with a rebuild and also the PO said he rebuilt it. Of course I realize that means jack. I've. Looked at Z1 many times but I just double checked and it seems I somehow over looked them on my petcock search. Thanks for the reminder I will pull it off today to make sure it has a 44mm spacing b4 I order. I'll keep you posted.
 
The '80 GS1000 petcock has the wrong hole spacing, does not have a lever, has a screwdriver slot to switch between prime and on, no reserve.
I've had my share of problems with GS1000 petcocks, I believe I had four and managed to get 3 working, the fourth was an oddball, think it was a 850 as it had the gas line on the front, didn't bother with it except for parts.
I had external and internal leaks, leaks from the petcock, external, and doesn't stop the flow of gas, internal.
Cleaning helps, especially that little breather hole that gets plugged at about the 2 o'clock position on the front of the block if you look at it from the front. That seal under the switching lever was bad in most cases, gets hard and compressed. There's also a check valve inside the vacuum line port that if it's bad, there's really not much you can do except clean and lube it, I used WD-40.
If you decide to take it apart pay particular attention to where all the pieces on the diaphram block are. Theres a small breather hole that goes from the front through the diaphram, through the diaphram block, they all have to line up for the diaphram to open and "close"

At Boulevard Suzuki you can get a new petcock for $263.01, it's not cheap.
If you clean it, you'll probably want to replace items 2, 3, and 4. and also the special sealing washers it doesn't show a part number for which is 09168-06023 for $1.16 each, or you may be able to get by with some teflon washers at an auto parts store.
http://www.boulevardsuzuki.com/fich...y=Motorcycles&make=SUZUKI&year=1978&fveh=2146

You can get rebuild kits on E-bay or other sources, we've had problems with those also, as some people claim the little O ring on the diaphram is actually too small to seal properly. I only used one kit and it worked for one of my petcocks.
Oh, here's a petcock rebuild tutorial.
http://members.dslextreme.com/users/storagecliff1/images/suzuki_petcock_rebuild.pdf
And two final things, be sure to tighten those screws that hold the diaphram block on very lightly and evenly initially as to allow the diaphram to find it's own center before you go cranking them down and when your finished run a gas line to a fuel can to test it. I've had better luck than most people rebuilding these, but it still was trial and error all the way.
Good Luck!
 
sedelen said:
The '80 GS1000 petcock has the wrong hole spacing, does not have a lever, has a screwdriver slot to switch between prime and on, no reserve.
I've had my share of problems with GS1000 petcocks, I believe I had four and managed to get 3 working, the fourth was an oddball, think it was a 850 as it had the gas line on the front, didn't bother with it except for parts.
I had external and internal leaks, leaks from the petcock, external, and doesn't stop the flow of gas, internal.
Cleaning helps, especially that little breather hole that gets plugged at about the 2 o'clock position on the front of the block if you look at it from the front. That seal under the switching lever was bad in most cases, gets hard and compressed. There's also a check valve inside the vacuum line port that if it's bad, there's really not much you can do except clean and lube it, I used WD-40.
If you decide to take it apart pay particular attention to where all the pieces on the diaphram block are. Theres a small breather hole that goes from the front through the diaphram, through the diaphram block, they all have to line up for the diaphram to open and "close"

At Boulevard Suzuki you can get a new petcock for $263.01, it's not cheap.
If you clean it, you'll probably want to replace items 2, 3, and 4. and also the special sealing washers it doesn't show a part number for which is 09168-06023 for $1.16 each, or you may be able to get by with some teflon washers at an auto parts store.
http://www.boulevardsuzuki.com/fich...y=Motorcycles&make=SUZUKI&year=1978&fveh=2146

You can get rebuild kits on E-bay or other sources, we've had problems with those also, as some people claim the little O ring on the diaphram is actually too small to seal properly. I only used one kit and it worked for one of my petcocks.
Oh, here's a petcock rebuild tutorial.
http://members.dslextreme.com/users/storagecliff1/images/suzuki_petcock_rebuild.pdf
And two final things, be sure to tighten those screws that hold the diaphram block on very lightly and evenly initially as to allow the diaphram to find it's own center before you go cranking them down and when your finished run a gas line to a fuel can to test it. I've had better luck than most people rebuilding these, but it still was trial and error all the way.
Good Luck!
Click to expand...

Steve, does the early petcock have a check valve buried inside the petcock body like the 1980 type? I know the leverless 1980 type does, which is one of the reasons they are so problematic to rebuild.
 
Nessism said:
Steve, does the early petcock have a check valve buried inside the petcock body like the 1980 type? I know the leverless 1980 type does, which is one of the reasons they are so problematic to rebuild.
Click to expand...

Ed, I do believe it does as per the tutorial calling it a blow back valve. I can't say I've ever seen it, have to break one apart for that. I do believe I heard something clicking when I sucked on the vacuum line. If it surely does any dirt would impede it's ability to function properly.
 
One thing to remember about 1980 GS petcocks - the GS1000G and GS850G that year still had traditionally styled (and functioning) petcocks. Evidently there was enough space in the original '79 GS850G design to allow for the use of that petcock with CV carbs.

The main difference between the '78 and '79 1000E petcocks and the 850/1000G petcocks is the tubing/screen design. The chain drive models had tubes that were much shorter and skinnier than the G models.
 
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Griffin said:
One thing to remember about 1980 GS petcocks - the GS1000G and GS850G that year still had traditionally styled (and functioning) petcocks. Evidently there was enough space in the original '79 GS850G design to allow for the use of that petcock with CV carbs.

The main difference between the '78 and '79 1000E petcocks and the 850/1000G petcocks is the tubing/screen design. The chain drive models had tubes that were much shorter and skinnier than the G models.
Click to expand...

Yes, but didn't the fuel line come from the opposite side?
There's a pic of an '80 GS1000G in this tutorial, the fuel line is facing towards the front and for '78, '79 GS1000C/E petcock the fuel line comes out facing the back of the bike.
http://members.dslextreme.com/users/storagecliff1/images/suzuki_petcock_rebuild.pdf
 
sedelen said:
Yes, but didn't the fuel line come from the opposite side?
There's a pic of an '80 GS1000G in this tutorial, the fuel line is facing towards the front and for '78, '79 GS1000C/E petcock the fuel line comes out facing the back of the bike.
http://members.dslextreme.com/users/storagecliff1/images/suzuki_petcock_rebuild.pdf
Click to expand...

Yes, but it should still work on a chain drive 1000, you'd just need to reroute the fuel line, correct?

The G model petcocks are a lot cheaper than the E model petcocks.
 
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Here are pics of the E model and G model petcocks, side by side.

The E model is on the left in both pics.

GEDC0281.jpg


GEDC0282.jpg
 
Griffin said:
Yes, but it should still work on a chain drive 1000, you'd just need to reroute the fuel line, correct?

The G model petcocks are a lot cheaper than the E model petcocks.
Click to expand...

Why didn't I think of that? I guess I did, so I went out to the bike and
really, you just don't have the room with the VM carbs, you got about a half inch from the end of the petcock block before it hits the fin of the carb, when you include the fuel line nipple, there's no room for the fuel line to make the turn without kinking. Unless you can figure out how to route a 90 degree elbow to the fuel line, also the vacuum line is tight, the 1000E goes up at an angle like 10 o'clock, you can see the tubing in the pic. Maybe you can cut enough of the fin of the carb to work, but who wants to do that?
Here's a pic of the area.
100_1521.jpg
 
The body is correct for my 78 GS1000, but the filter appears to be from a later G model of some sorts. It holds back fuel okay, but as far as seeing at what amount of fuel left in the tank before it will need to be switched onto reserve compared to the original one? I can't. The fuel tank is necked...

PICT3548.jpg
 
rustybronco said:
The body is correct for my 78 GS1000, but the filter appears to be from a later G model of some sorts. It holds back fuel okay, but as far as seeing at what amount of fuel left in the tank before it will need to be switched onto reserve compared to the original one? I can't. The fuel tank is necked...

PICT3548.jpg
Click to expand...

I've got a 1000E tank that looks about like that. Used M.E.K. to dissolve the old Kreem job in it, then some stripper to remove the rattle can paint job that was on top of the professional repaint that was on top of the bondo (good job, had no idea it was there until..) that was on top of the original paint (was a black '79 tank at one time).

Eventually I'll fix it up to stock paint and decals, get a '79 tailpiece painted to match, then wither sell them here or use them for a "non-skunk" change of pace on the '78.
 
You guys are awesome. Judging from the picks I at least have the correct one on my bike (E not G) . Unfortunately I have not been able to mess with it. My wife went into labor on Tuesday (6/19) and on 6/20 gave birth to Chloe our beautiful baby girl. First child I might add. I will take the info and hopefully at least have tome to take it off and clean it since I'm taking several days off. The PO said he rebuilt it if that's true the parts should be in good shape still and i can clean it out. I'll get back to you later. Thanks again for all the info.
 
Congratulations! Now you really have your hands full.

In the meantime, I'd just soak your petcock in gasoline and clean it thorougly, blow it out and see if it leaks before you tear it down, dirt, especially that little breather hole getting clogged creates allot of the problems.
 
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