1980 petcock

[Anonymous]

Hi everyone!
I bought a 1980 550L with a leaking petcock, He told me it leaked. $400.00 bucks for it was to good to pass up. got it for my 18 y/o son to learn on and ride.
I bought a new petcock off ebay. $42.28 delivered.
This year petcock has no lever on it, only a slot that looks like a small scewdriver will turn it.
Looking at the petcock, At 11:00 oclock on it is the letters PRI. At 12:00 oclock there seems to small raised arrow pointing down. no other marks! I guess they have no reserve on this model. I am sure I will have to prime the carbs as I keep just enough gas in it to start it now and then.
How do I prime this bike and then return it to the run position?
I did use the search feature and found no answer for this. Tech area also with no luck.
I am glad I found this board! Ive ridden the bike a few times now, These Gs bikes are quite neat!
The amount of information you all have here is awsome!!!
Thank you
marty

1980 GS 550 L
1995 Shadow 1100 ace
1988 Shadow vlx 600

[KGB]

It's a complete vacuum system
Same as on my 1980 GS1000S.

Once the bike is started, like after sitting for the winter, leave it horizontal, this is "on" it will go over to reserve on it's own.

If you have agas guage, and trip meter, learn how far you can go and where the guage sits for how many gallons you've used.
My tank is 5.5 gls US.
When it hits the red mark on the guage I look for afuel station,quickly.
I have about 1 gl left. Or about 200 miles used.

[Planecrazy]

Hey Keith,

I was unaware that turning the "slot" did anything on the '80 petcocks. Someone once said that turning it did absolutely nothing. Are you sure there is actually a difference depending on position?

Thanks!
Steve 8)

[KGB]

Hey Keith,

I was unaware that turning the "slot" did anything on the '80 petcocks. Someone once said that turning it did absolutely nothing. Are you sure there is actually a difference depending on position?

Thanks!
Steve 8)

Yes.

It moves the internal valve to allow prime.
I tried it a few times, just to make sure it worked.
I needed it again this spring. The S sat for almost a year, elctrical
Tried a 130 watt bulb 8O and fried some wiring and the fuse block....
Now that it's fixed, many $$$$,yes 4 figures
It runs fine.

It does work, at least on mine there is adifference.
I used it a few times to drain the tank, like this year and it still works.

Don't know who said otherwise, but I can prove mine works.

[Anonymous]

KGB,
Thanks for the info! I think I understand what ya said. But I am a little fuzzy on one part of this.
Do I turn the petcock to prime manualy, And then it automaticaly resets to the run position once it starts running? So do I turn the slot vertical to prime with a screwdriver., And then it resets itself to a horizontal run position itself after its running.
Jeepers, Ive changed petcocks on both of my shadows, but this vacuum type is new to me!
I know there is gas in my oil so that is getting changed along with the petcock.
Thanks Guys, This board rocks!
marty


1980 GS 550 L
1995 Shadow 1100 Ace
1988 Shadow vlx 600

[KEITH KRAUSE]

The correct starting prodedure for that petcock is: turn the slot to vertical, which is prime. Start/crank the engine. This petcock needs engine cranking vacuum to make the fuel flow, even in the prime position. Once the bike starts and is operating smoothly, turn the slot to horizontal, which is on.
There is no reserve as said earlier. You need to watch the speedo and learn what your mileage is.

[Anonymous]

Thank you!
Pat yourselfs on the back!!! this is a great place!
Glad I found you all!
I'am very pleased with the brotherhood shone on this board!
marty

[Anonymous]

If the petcock needs vacuum to make fuel flow in the run position, why do you need to put it on pri. if it will still need vacuum for fuel to flow?

[Anonymous]

I agree with rphilips. If you needed vac to operate prime, it would be no different from run.

[KEITH KRAUSE]

I agree with rphilips. If you needed vac to operate prime, it would be no different from run.

I've wondered the same thing.
I can see the need for a gravity fed prime, but not a prime that still needs cranking vacuum to operate. It seems that you would just have two "ons" then.
I'm just telling you what the Suzuki factory manual says about its operation. And it says the engine must be cranking to initiate fuel flow, even in the prime position.
The 1980 petcock always was an oddball.

[Anonymous]

I suspect that we now know why this design was abandoned, either that or the manual may have had a typo.

[KEITH KRAUSE]

I suspect that we now know why this design was abandoned, either that or the manual may have had a typo.

Well, I don't know. I'm just glad I don't have one of em'.
KGB says he has one and he drained the tank with it in prime. I don't know if he "initiated fuel flow" by first cranking the engine and it just continued to flow after he stopped cranking? I'm sure you wouldn't crank it the entire time until the tank was dry. If he did neither, and the tank drained, then the manual's wrong I guess. The diaphragm/parts illustration of the 80 petcock IS different than the '79 petcock in the same manual.

[KGB]

I suspect that we now know why this design was abandoned, either that or the manual may have had a typo.

Well, I don't know. I'm just glad I don't have one of em'.
KGB says he has one and he drained the tank with it in prime. I don't know if he "initiated fuel flow" by first cranking the engine and it just continued to flow after he stopped cranking? I'm sure you wouldn't crank it the entire time until the tank was dry. If he did neither, and the tank drained, then the manual's wrong I guess. The diaphragm/parts illustration of the 80 petcock IS different than the '79 petcock in the same manual.

I opened the fuel cap and it flowed.
I guess once any pressure in the system was released, it let it flow.
Unless mine is defective, which if it is after 16 years.....I'd have found out.
This does need to be put back to "normal" horizontal position after starting. It does NOT go back on it's own.
Suzuki is good, but not that good

Be careful you don't crimp the gasket around the petcock when re-installing it.

[KEITH KRAUSE]

Keith, just curious. If you have a factory manual for your bike, does it say the same thing about the engine must be cranking to initiate fuel flow, even in the prime position? I have the manual that covers the '79 model line and also the '80 GS1000E/ST.

[KGB]

Keith,
All I have is a clymer, British version.


When I swapped tanks a few years ago, I drained it thru the petcock.
Opened the cap and it flowed.