New member, 1980 GS550L

[Hoppy]

Hi folks, thanks for having me!  I just picked up this bike, seller could not get it started. 

Going through it now, got good spark and it runs (rough) on starting fluid. So going through fuel.

Will have many questions, I'm sure. First one: what's up with the petcock? There is no switch and a guy told me it runs on vacuum? Trying to rule it out but need to understand it first. 

Thanks in advance!

[TonyGee]

yes its just a vacuum tap. no RES or ON position, but using a screwdriver you can use prime

[Hoppy]

Thank you TonyGee. Can I run it on prime (that just means the valve is fully open?)  until I get her running, then hook up the vacuum to test out the petcock? I know it will spill some gas, but I am in problem solving mode 

[TonyGee]

58 minutes ago, Hoppy said:

Thank you TonyGee. Can I run it on prime (that just means the valve is fully open?)  until I get her running, then hook up the vacuum to test out the petcock? I know it will spill some gas, but I am in problem solving mode 

yes you can if you are trying to rule out a faulty fuel tap, but when done don't leave it on prim 

[Hoppy]

So, bike is running great on auxiliary fuel, but starving for gas when tank is on.  Looking like the original diagnosis was correct, petcock not working.

Can these be rebuilt? Looked for a kit with no luck so far. Can they be replaced with regular petcock with manual valve?

[TonyGee]

plenty of good used taps around with a lever and with ON and RESERVE, just make sure they are the same hole spacing. 

[Dezza]

What Tony said: your fuel tap is broken. It should have a lever so it can be moved between on, off and prime. It's also been leaking, which is why there's a brown stain around one of the mounting bolts. I'd go for a replacement tap and new seals between the tank and tap. When it's drained it will also give you an opportunity to flush the tank out and check the cap, vent and so on .

[Poldark]

Yes, you need to replace that petcock.  When in the "on" position, engine vacuum is required for fuel flow.  "PRI" or "prime" does not require engine vacuum, constant fuel flow.  California models did not have the prime position.

[ProducerBill]

I replaced my 1981 GS550L petcock with: https://www.Eblag.com/itm/292730824423?chn=ps&_trkparms=ispr%3D1&amdata=enc%3A1V4YqbfPfQ7SMg-BvYRYsvw76&norover=1&mkevt=1&mkrid=711-117182-37290-0&mkcid=2&mkscid=101&itemid=292730824423&targetid=&device=c&mktype=pla&googleloc=9017453&poi=&campaignid=20394363341&mkgroupid=&rlsatarget=&abcId=9317265&merchantid=101499179&gclid=CjwKCAjwxOymBhAFEiwAnodBLE6g5tp_oqQGXci5qTgkh1_8HsJapdCJWZ7eghnEuZYYGb505dgdmRoC1uoQAvD_BwE

Didn't cost an arm and leg and worked just fine. Vacuum function works correctly.

Good luck on getting it on the road my 1981 GS550L adventure has been fun. Here is my sister learning on it.

Also if you need/want a LED headlight upgrade idea let me know.

[Thierry]

ProducerBill, did the original petcock on your GS 550 L have a lever, or was it a vacuum one?

I wanted to replace the vacuum petcock on my 1979 GS 1000 E with a petcock sporting a lever, however I was advised by a mechanic specialising in 1970s Suzukis that it is not possible, as the spacing of the holes is different  (GS 1000 Es came with both types of petcock).

Hoppy, hopefully the spacing is the same for both types of petcock on your GS 550 L; if this is not the case, then you may have to carry on with a vacuum petcock.

Edited March 20 by Thierry
clarity

[ProducerBill]

On 3/20/2024 at 7:26 PM, Thierry said:

ProducerBill, did the original petcock on your GS 550 L have a lever, or was it a vacuum one?

I wanted to replace the vacuum petcock on my 1979 GS 1000 E with a petcock sporting a lever, however I was advised by a mechanic specialising in 1970s Suzukis that it is not possible, as the spacing of the holes is different  (GS 1000 Es came with both types of petcock).

Hoppy, hopefully the spacing is the same for both types of petcock on your GS 550 L; if this is not the case, then you may have to carry on with a vacuum petcock.

The original petcock did have a handle. It was tiny, but there was one. It is true the replacement is a bit larger, but it fit. Maybe it will not fit a 1000E because the engine might be larger, but the 550L had more then enough room for the replacement.

Here is a picture of an old from one at a show.       Here is the replacement on mine.

Wish the pictures where more straight on but this is the best I have on hand.

[gs7_11]

The problem Hoppy will have is that there are 2 tap mounting hole spacings on Suzukis of this era, 44mm and 50mm.

The taps with no lever have a 50mm spacing and so far, I've never seen a suitable replacement with a lever.

[TonyGee]

4 hours ago, gs7_11 said:

The problem Hoppy will have is that there are 2 tap mounting hole spacings on Suzukis of this era, 44mm and 50mm.

The taps with no lever have a 50mm spacing and so far, I've never seen a suitable replacement with a lever.

yeah ive looked for a tap with the lever with 50mm spacing and had no luck !!!!  the tap on my ET tank is 50mm but would prefer a RES position as I probably won't have/use a fuel gauge. 

[Gixer1460]

None of my bikes has ever had a fuel gauge and although they do have reserve i've never actually run out. If you have a trip meter, re-set it everytime you fill up and providing you know approx tank range, you know when to start looking for fuel!