Petcock questions for my '81 GS650GT and unrelated? fuel leak.

[hank2]

This past evening I was determined to get a ride in for the first time in several days on my '81 GS650G. 95F heat. Since it was so hot, I first tried starting without choke. Sputtered a bit but wouldn't idle. Tried choke and started but ran unevenly, not normal. In a short while I noticed gasoline quickly puddling under the bike. Shut it off. Determined that gas had been flowing out of the vent hose and I believe from carb 2. It did stop flowing after shutdown. Tried again, same result. Petcock was left in the normal middle down on position. Zero ethanol fuel always used.


On a whim, I grabbed a rubber mallet and a box wrench and gave the float bowls on 1 and 2 a few light whacks. I left it sit a couple of minutes and then it started just fine, no further leaking and ran out as good as ever after a short warmup. Did about 50 miles with no trouble including a couple of restarts. I know only enough about carbs to get in trouble or fuddle through. I suppose that with the whacking I freed up a sticking needle and seat? Or sticking float otherwise?

I don't think that the petcock was part of the trouble with last nights folly or was it? Anyhow, I've been considering a new petcock since the bike is 40 years old with nearly 30k miles. I've known that the correct '81 oem "X" petcock is NLA from Suzi. For the '81 only, it's mounted near the rear of the tank, ( not moved to middle like the '82-83 fuel gauge equipped units). Mine has the outlet facing forward. The '82-83, which you can still get, has outlet facing rearward. So that substitute is a deal breaker. Other aftermarket Suzi. ones all seem to follow the rear facing outlet style, including the K&L. I've read that the '81 and '82 have different reserve straw lengths which wouldn't have concerned me much. Mine also was used on the '81-82 E model chain drive bikes but that's no help of course.

So, where does that send me? Thinking Pingel maybe. Pingel doesn't list my bike in their appl. chart. If I can believe some sources, the GS650G has a 44 mm bolt pattern spread ( about 1 3/4 in.) Pingel has adapters with that spread, but no info on length and width of adapter plate. Available in 1/4 NPT or 3/8 NPT. Most of the Pingel petcocks are available in either of those sizes,

Possible problems:

What size adapter screws does Pingle use for their mounts. What did Suzuki use?

What length and width mount plate would work on my Suzuki? That I can measure soon, but don't know Pingel's specs.

What size fuel hose does my bike use? Most or maybe all Pingels seem to be 5/16 barbs about 7.2 mm?

Is my petcock hole in my tank compatible with what size Pingel?

Are the Pingel straw towers too tall?

I'm assuming that my bike uses a single fuel feed, or is it two? Haven't looked yet.

Has anyone done a successful Pingel mount on an '81 GS650G? What did you use? I would enjoy getting away from the vacuum op and to a gravity feed. With reserve and off. Enjoyed the excellent Karcoma gravity feeders on my old Beemer airhead for years.

Any thought on what my overflow situation likely was?

This a lot of questions but thankful for any knowledge on this model and the petcocks.

 

[Grimly]

Not got a 650, but last year I fitted a Pingel 44mm plate to the 850 tank and on it put a Harley copy manual valve.
I had to use a round file to take a tiny bit out of the central slot of the tank fitting, but that's all.

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[rphillips]

Sounds like your petcock is operating properly as leak stopped when eng. was turned off. All the vac. does is automatically turn fuel off when eng. is turned off & automatically turn fuel on when eng. is running. All are just gravity flow. Also the ones I've seen, not seen one from a 650, the back is square & can be rotated so the fuel & vac. nipples point in the direction you need. Yes Suzuki did have 2 different mounting hole spacing. There was a thread on here a few days ago about installing a pingle, info. there may be of help.

 

[hank2]

Thanks for the info and inputs, gents! Grimley, thanks for the photo. It does seem that my current petcock is working properly. I started it up today and didn't have an overflow leak. On looking at photos of the the '82 style oem and aftermarket ones, it does appear that you could remove the 4 screws and rotate the back. Unless I'm just not seeing something, I think that would move the vacuum fitting towards the front but leave the fuel fitting pointing rearward? I may get a Pingel plate and possibly their petcock and do what Grimley did. I hope to get the tank off soon and get a number of delayed things done at that time. Valve lash, oil leaks, new hoses, clutch and throttle cables, etc.

I may add a fuel filter after the petcock if I can get one that won't impede the flow very much.

Anyone have info on fuel hose ID in the GS era? 3/16, 1/4 or 5/16 ID's? I know that 7 mm ID was a thing ages ago on the old fabric covered line.

 

[earlfor]

Thanks for the info and inputs, gents! Grimley, thanks for the photo. It does seem that my current petcock is working properly. I started it up today and didn't have an overflow leak. On looking at photos of the the '82 style oem and aftermarket ones, it does appear that you could remove the 4 screws and rotate the back. Unless I'm just not seeing something, I think that would move the vacuum fitting towards the front but leave the fuel fitting pointing rearward? I may get a Pingel plate and possibly their petcock and do what Grimley did. I hope to get the tank off soon and get a number of delayed things done at that time. Valve lash, oil leaks, new hoses, clutch and throttle cables, etc.

I may add a fuel filter after the petcock if I can get one that won't impede the flow very much.

Anyone have info on fuel hose ID in the GS era? 3/16, 1/4 or 5/16 ID's? I know that 7 mm ID was a thing ages ago on the old fabric covered line.

Gas line is 5/16" I.D.

 

[LAB3]

I've seen the adapter plate you'd need for sale on eBay, you might want to look there.

 

[hank2]

Gas line is 5/16" I.D.

Thanks for that info.