Need help with tank/petcock interchange

[althomas101]

Hi all, I did search the forums for the answer first. I recently purchased a 1979 GS100L and the petcock diaphragm is leaking. I don't like the design of the one I have on it, as it has no reserve function nor an Off position. It simply has run and prime. Here is the one on the bike now http://www.newmotorcycleparts.com/fu...cocks_suz.html it is the second one down PETCOCK-4357. I would especially would like the 1978 petcock as it not only seems to be vacuum operated but it is full function: Off, Run, Prime, Reserve.
However it seems that Suzuki used a number of different petcock designs around that time even on the same model but between the different designs like my L. Mine has a 50mm bolt spacing and it appears that they came in 40mm, and 44mm. My question is what model/year petcocks will fit on my L tank? If any of you don't mind measuring some petcocks you have in your parts bin or on your bike that interchange information I'm sure will come in handy for others down the road. Any information provided would be greatly appreciated on my part.

[Guest]

All I can say is a stock '79 GS1000L has what I believe the lever for switching around the various settings, at least thats what I believe from looking at the parts fiche. Perhaps an '79 GS1000L owner will chime in and give us more insight.
Item 15 in the parts fiche, $80 and change at Boulevard Suzuki.
http://www.boulevardsuzuki.com/fiche...1979&fveh=2147

[althomas101]

From what I can tell the stock 79 L petcock had a lever and only had a run and reserve function but it was superseded by the 80 petcock that only has run and prime.

[althomas101]

Well after ordering a rebuild kit for my bike the diaphragm was the wrong size then I ordered a suzuki replacement petcock that also was WRONG!! The mounting bolt spacing is 45mm instead of the required 50mm. So if Suzuki parts fiche is wrong I don't know where to go now other than getting some sheet metal and cutting out the old mount and fabricating a new one. I guess I'll get started today on that. This is a real bummer since I got her running on all 4 cylinders now, tuned her up and synced the carbs. And while the tires and brake lines are ancient it is ready for a test ride. I really want to see what she's like.

[tom203]

That's a drag- maybe someone replaced your tank with a 80 tank with the dreaded leverless petcock. Who knows what suzuki was thinking that year! The 50 mm spacing with a lever doesn't appear common in a vacuum petcock.

[althomas101]

Someone else suggested that as well and I think your right. I wish I had know it had the wrong year tank before all of this I'd be $80 ahead of where I am now. I decided to make an adapter out of bar stock, I'd rather have a reserve.

[tom203]

Someone else suggested that as well and I think your right. I wish I had know it had the wrong year tank before all of this I'd be $80 ahead of where I am now. I decided to make an adapter out of bar stock, I'd rather have a reserve.

If you can make one (have access to CNC milling machine ?), make a few- others have lamented having to use the dreaded 80 petcock.

[althomas101]

I made it with a drill press and a bench grinder, I'll post some pics and dimensions.

[Rover]

Please post some pics of your bike and tank also,curious what you have with the 80 petcock.
Thanks

[althomas101]

I have a 1979 GS1000L here is my picasa link. https://picasaweb.google.com/1026018...4202563/GS1000

[althomas101]

Here is a link to my picasa album detailing the conversion to a 1979 petcock.

https://picasaweb.google.com/102601857000444202563/GSPetcockConversion