Need to determine correct fuel petcock gasket

[GSOH]

I recently bought a 79 GS550E and I believe it does not have the original petcock. The one on it now has a reserve and On function, no prime function. So, it leaked a little bit of gas when I got it so I started only keeping about a gallon or so of gas in it. Running out of gas forced me to look into getting a new gasket/o-ring. I took it to a local used parts shop and they put a used o-ring in it with gas resistant sealer. Installed and still leaks, worse than before in fact. With only a gallon or so of gas it's fine. However, if I fill up the tank it leaks really bad.

I ordered the exact gasket for my bike, but it looks nothing like what was on the bike. Can anyone help me determine which gasket /o-ing I need to get in order to get my back back up on the road?

[kdo58]

not sure what gasket you need but here is some info that will be helpful

http://members.dslextreme.com/users/bikecliff/

[sedelen]

Very peculiar.
I just looked up the petcock for the '77-'79 GS550E and it appears to have the older style petcock on it in the fiche.
But that petcock you have looks to be the newer model. Funny thing is the hole spacing is different between the two I believe, but I could be wrong. So.......... that being said, for that petcock to fit a '77-'79 tank the tank was either modified or it is a later year tank (I believe) You need to find out for sure.

Here's a picture of the old style petcock.


Here's a picture of the newer style petcock in this E-bay auction. If you read in the description it says for '80 and newer.

http://www.ebay.com/itm/Suzuki-GS1100-GS1000-GS850-GS750-GS700-GS650-GS550-GS450-1980-1985-FUEL-PETCOCK-/400329487081?pt=Motorcycles_Parts_Accessories&hash=item5d357f32e9&vxp=mtr

Here's a parts fiche that show's a '80 petcock, gasket is no. 2 and get those sealing washers for the bolts, number 4.

http://www.boulevardsuzuki.com/fiche_section_detail.asp?section=93032&category=Motorcycles&make=SUZUKI&year=1980&fveh=2107

page 262 shows your petcock in this 550 service manual page 262, it is for a T model which is a '80 year model.

http://www.mtsac.edu/~cliff/storage/gs/GS550_77-82_all.pdf

[kdo58]

http://www.buyatvsonline.com/gas-valve-fuel-petcock-07-for-chinese-atvs-dirt-bikes-go-karts-p-9491.html

i bought one of these cheap

[GSOH]

I think you are quite right with this being from an '80 model tank. Thanks for the links. I will have to investigate a bit. I think part of the bike is a frankenride.

Very peculiar.
I just looked up the petcock for the '77-'79 GS550E and it appears to have the older style petcock on it in the fiche.
But that petcock you have looks to be the newer model. Funny thing is the hole spacing is different between the two I believe, but I could be wrong. So.......... that being said, for that petcock to fit a '77-'79 tank the tank was either modified or it is a later year tank (I believe) You need to find out for sure.

Here's a picture of the old style petcock.


Here's a picture of the newer style petcock in this E-bay auction. If you read in the description it says for '80 and newer.

http://www.ebay.com/itm/Suzuki-GS1100-GS1000-GS850-GS750-GS700-GS650-GS550-GS450-1980-1985-FUEL-PETCOCK-/400329487081?pt=Motorcycles_Parts_Accessories&hash=item5d357f32e9&vxp=mtr

Here's a parts fiche that show's a '80 petcock, gasket is no. 2 and get those sealing washers for the bolts, number 4.

http://www.boulevardsuzuki.com/fiche_section_detail.asp?section=93032&category=Motorcycles&make=SUZUKI&year=1980&fveh=2107

page 262 shows your petcock in this 550 service manual page 262, it is for a T model which is a '80 year model.
http://www.mtsac.edu/~cliff/storage/..._77-82_all.pdf

[sedelen]

I think you are quite right with this being from an '80 model tank. Thanks for the links. I will have to investigate a bit. I think part of the bike is a frankenride.

Tanks get swapped around quite frequently providing they will fit.
Then you have problems such as yours where you think it's one year and it's another, so the parts for it don't match. Worse yet some models because of the difference in petcocks and carbs a new tank won't fit because the different petcock doesn't have room because of the carbs.

[tom203]

You need to determine centerline bolt spacing on tank- might be 44mm or 50mm- ( I got older petcock with 46 mm spacing no clue where it came from) and get right petcock.

[GSOH]

You need to determine centerline bolt spacing on tank- might be 44mm or 50mm- ( I got older petcock with 46 mm spacing no clue where it came from) and get right petcock.

i did measure and the spacing is closer to 44 mm. would that make it an '80 or newer?

[Mr. Sinister]

Looks just like the petcock on my 81. The one shown in the Clymer manual I have is different. I got my rebuild kit here: http://www.oldbikebarn.com/Suzuki-GS...category=73759

The large o-ring goes in the base between the petcock and the tank. The smaller o-ring goes on the select lever. You have to pop the little stamped plate off behind the lever to release it. The diaphragm is pretty self-explanatory. Just make sure you don't lose the springs behind the fuel lever and under the cover with the 4 screws in it. I recommend taking a few pictures of what the petcock looks like assembled, so you reassemble it correctly. You know it's fixed when you can apply a little suction to the vacuum hose, and feel the diaphragm pop in and out.

[GSOH]

i was planning on just replacing the gasket between the tank & petcock as that appears to be the source. i would assume this goes in dry with clean surfaces on tank & petcock, no?

that rebuild kit does seem pretty cheap. thanks for the info & the reminder to take pre demo photid for reference.

[tom203]

There are special sealing washers under the petcock mounting bolts- likely available at hardware stores- 1/4 inch size works fine.

Some folks have had no luck with rebuild kits.whole new petcock with tank oblong o-ring can be had for $50 to $60

[sedelen]

i was planning on just replacing the gasket between the tank & petcock as that appears to be the source. i would assume this goes in dry with clean surfaces on tank & petcock, no?

that rebuild kit does seem pretty cheap. thanks for the info & the reminder to take pre demo photid for reference.

Considering you don't have a properly fitting O ring between the tank and petcock, I would assume that's the source of your leak. However you may need to replace those sealing washers that go under the bolt heads because they need to seal also. You can probably get away with some teflon washers if yours don't hold. If you have to order that O ring you might as well just order the washers for it also. See the second link in my previous post to you.
I ususally coat the o ring with a lubricant, what's most important is the mating surfaces being clean so the O ring can seal properly.

[Mr. Sinister]

i was planning on just replacing the gasket between the tank & petcock as that appears to be the source. i would assume this goes in dry with clean surfaces on tank & petcock, no?

that rebuild kit does seem pretty cheap. thanks for the info & the reminder to take pre demo photid for reference.

That's what I did, no leaks.
My rebuild appears to have been unsuccessful, as the bike will only run with the petcock on prime. I have ordered a replacement from Z1.