'79 vs '80 GS1000 E/S/base-model gas tank differences?

[Chuck78]

Are there any major cosmetic differences between a 1979 GS1000 fuel tank and a 1980? I know the petcock location is supposed to be different between the two, the '80 had CV carbs & as such the new Petcock had to be moved rearward more toward the seat. I also had read that your earlier petcocks do not even fit on the 80 model, I assume a different bolt spacing length.

Are there any major aesthetic cues as installed on the bike that would differentiate them?

Are there any other imposter tanks that to an untrained I would look very appropriate? I know I have read that the 80-81 GS750E and possibly 1100E tanks are a direct swap, correct? But to the trained eye, are they immediately apparent?
Are there any aesthetic obvious differences such as the 80 or the other compatible model tanks being taller, more angle sweep back from the center to the sides up front, making the sides of the tank a lot shorter visually front-to-rear than tank measured at top front to rear?

Thanks!

Chuck

[80GS1000]

IIRC the 78/79 tanks had the grooves down the sides of the tank and tail cowl for the "Skunk" paintjob. My 80 GS1000E has no such grooves.

[Chuck78]

The tank in question:

[Chuck78]

IIRC the 78/79 tanks had the grooves down the sides of the tank and tail cowl for the "Skunk" paintjob. My 80 GS1000E has no such grooves.

It's just the '78 tanks that had the sides indented for the skunk stripes, 79 and 80 were smooth sides.

[Griffin]

The '79 tank has the petcock location farther forward with mounting hole spacing for the old style lever petcock. The '80 tank has the petcock location farther aft, with wider hole spacing for the dreaded '80 leverless (insert screwdriver) petcock.

This was deemed necessary to allow clearance for the change from VM to CV carbs on the '80 model. The other '80 models that use that petcock are the 1100E/L, 750E/L, and 550E/L.

The 1980 GS850G and GS1000G use the older lever-style petcock.

[Chuck78]

The '79 tank has the petcock location farther forward with mounting hole spacing for the old style lever petcock. The '80 tank has the petcock location farther aft, with wider hole spacing for the dreaded '80 leverless (insert screwdriver) petcock.

This was deemed necessary to allow clearance for the change from VM to CV carbs on the '80 model. The other '80 models that use that petcock are the 1100E/L, 750E/L, and 550E/L.

The 1980 GS850G and GS1000G use the older lever-style petcock.

Were the 79 vs 80 tanks the same otherwise?

The GS850G & GS1000G don't bolt onto the GS1000 chain drive non-L models, do they?

Is a GS1000G tank shorter in length than a chain drive E?

[Chuck78]

So one coukd differentiate a 79 vs 80 by measuring the petcock bolt hole spacing?
But identifying an unknown tank - it could still be perhaps an incompatible GS1000G shafty model then?
Are shafty gas caps all offset? Or are some centered?

Any other ID pointers appreciated. Thanks for the help thus far, Griffin.


Perhaps a Pingel adapter would be in order for a leverless 1980 petcock tank then? If such adapter exists.

[Griffin]

So one could differentiate a 79 vs 80 by measuring the petcock bolt hole spacing? Yes.

But identifying an unknown tank - it could still be perhaps an incompatible GS1000G shafty model then? They are not directly interchangeable. The 1980-1981 GS1100E tank is a direct bolt on, as is the 1980-1982 GS750E tank. I actually prefer the way they look on a 1000E to the stock tank.

Are shafty gas caps all offset? Or are some centered? The GS850/1000/1100G tanks all have offset filler hatches. The GS 750/1000/1100E tanks are centered.

Any other ID pointers appreciated. Thanks for the help thus far, Griffin.


Perhaps a Pingel adapter would be in order for a leverless 1980 petcock tank then? If such adapter exists. They do exist. Just make sure you have clearance for it.

I have not checked clearance of any petcock on an '80 1000E because I've never had access to one to see what tank/petcock combinations may fit. I do have a spare GS1100E tank, haven't measured it to see if it is an '80 or '81. I know the '81 GS750/1100E tank with the '80s style (small lever) petcock will fit on a '78 and clear the VM carbs, but not sure with the CVs on the '80.

Here is my "Wall of Spares":



Top Row, left to right:

'80 or '81 GS1100E
1978 GS1000E
1984 KZ700A
1985 GS700E/ES
1982 GS650E
1981 GS850G

Bottom Row:
1982 GS450E
1981 GS450E
1981 KZ550A
1983 GS1100ES
1982 GS850G

I could take some measurements on specific ones and let you know what they come out to if you'd like.

The toaster oven is for powder coating, not making sandwiches, by the way.

[80GS1000]

Hope this helps - the bolt hole spacing on the Pingel for my 80 GS1000E tank is 50 mm.

The Pingel application chart shows either 44 mm or 50 mm bolt spacing for the adapters. Presumably the earlier GS1000s had the 44 mm spacing for the VM carbs and the later (80+) models had the 50 mm spacing for the CV carbs.

http://www.pingelonline.com/images/Pingel_Powerflo_Fuel%20_Valve_Application_Chart.pdf

Apparently I need to clean the bottom of my tank but here's the spacing.

[Chuck78]

I posted a thumbnail/link above, but this is the tank I'm looking at buying. I have a 78 GS1000C that Joe Humbert sold me minus wheels, carbs, & airbox, & included a very smashed up 78 tank. I bought another 78 tank on ebay, rattle can exterior with only a few very minor little dings in it, but it turned out to be the most internally-rusted gas tank I have ever set my eyes upon. The metal is very thin, the interior is completely rusted with all kinds of loose rust scale shaking around inside of it. It'd do okay as a restoration candidate for a show bike, but I'm looking for something with more integrity (metal thickness,no pinholes to worry about patching with tank liner kits).

I honestly think that the 78-79 GS1000 tanks must have been made out of some different steel alloy than other GS models, similar to how 1980's Toyota pickup truck beds rust out SEVERELY, while the truck cabs have a normal automobile corrosion life... I have read of more pinhole repair jobs and liner jobs in 1000 tanks than I have any other GS model!

Again, this is the tank I'm trying to I.D.:


Griffin, if you don't mind measuring the 1980 leverless petcock style petcock bolt hole spacing for me, that would be much appreciated. I have two trashed 1978 GS1000 tanks here, as well as a couple 77-79 750 tanks with the same spacing, so I can compare pretty easily.

Thank you.

The tank in question here is of the centered gas cap variety, so according to your information is not a shaft drive model thankfully.

[Chuck78]

Aha... Posted as I was typing, thank you sir!

[salty_monk]

Pretty sure this was an 81 tank. I think I actually ended up using an 85 750ES petcock, jacking the back of the tank up slightly & reshaping a spare carb top with a dremel to get clearance. I reverted back to the proper skunk tank after the trip....

P1000074 by salty_monk, on Flickr

[Nessism]

1978 1000 C/E had the indent and large petcock.
1979 1000 N/E lost the indent but kept the large petcock. Emblems attached to a recessed bar. 1979 1000S tank is same but has no recessed bar for emblem attachment.
1980 1000 E used the leverless petcock and the recessed bars to attach the emblems. The 1980 S tank has no emblem bar but the leverless petcock.

[kochic]

I only have skunk tank I cannot really help but
if you trim a little the rear top bracket of the carburetor number 1 you can fit a later style petcock (gs1150- GK) with CV carbs on a GS1000c/e with a '78 tank.
Marc