Ghost Leak '85 GS550L Carb #1

[rwbersin]

Hello Listers,
My name is Bob. I have spoken with Cliff and he suggested I put this one to all of you experts!

I will be right up front with you, I am a Yamaha XJ enthusiest, but my wife's ride is a sweet 1985 GS550L with barely 5K miles on it.

The bike had been running great but I did not get her winterized in time and then she sat for nearly 2 years in the tractor shed here at the horse farm where we live. I was able to resurrect the ole girl to a point using Seafoam, but finally took her in to a shop run by a very reputible pair of brothers. I know... I can hear all of you grumbling already!

Anyway, I told you, I am an XJ guy, not a GS guy. Although I have to say, it really is a sweet ride when she's working.

So, the only other thing I had done before taking the bike into the shop was to blow some air into the fuel line just after the petcock connection. I received my reward nearly in my face but fortunately the surge of gasoline hit my shoulder.

The guys in the shop did a soup to nuts job, from etching the rusty tank due to an insufficient level of fuel in the tank for those 2 years all the way to boiling the carbs, replacing the valve seats & springs, several jets, etc, etc, etc...

The bike ran great until we took her out for our first ride. About 15-20 miles into the ride and every ride thereafter, carb #1 starts leaking. The guys at the shop have done the following:

Checked Engine Intake Valves
Replaced Cracked Manifold Boots
Swapped Floats From one Carb to the other
Purchased a whole other used carb, cleaned and rebulit it and still... Gas Leak

There is some Ghost in or around the fuel supply to or from carb #1. I asked them today if they had run it around with a test tank so they could bypass the tank petcock. I did not know how it could, but just wondered if that could be failing some 15 miles into the ride somehow.

Anyway, I thought I would put this out to you all and see if any one has ever come across a Ghost like this one. Believe it or not, my wife has been bugging me about wanting to ride so much, she actually rode my XJ550 Maxim a few times, but she's ready for her "Suzy" to be back!

Thanks for your help!

Bob Bersin

1981 XJ650H Maxim
1982 XJ1100L Maxim
1983 XJ550K Maxim
1985 GS550L
1987 CBR600 Hurricane (for sale)

[rwbersin]

Resolved!

Well, my friend took the bike out with an IV tank; said it looked pretty weird, but discovered that the problem must indeed have been in the petcock itself. All tests that could have been done on the petcock had been done except to check the actual inner workings of the little rubber check valve for the vacuum mechanism.

Apparently there is a "pulse" action to the vacuum mechanism that acts sorta like a "pump". In this case however, he could not check this without taking that part of the petcock apart and doing a visual inspection. However this meant destroying the petcock to do this... Not a problem! the little rubber check valve piece had deteriorated and dissenigrated so that eventually the carb could not keep up with the continual flow of fuel.

Hopefully this makes a great deal of sense and is causing the "ah-ha" response from most of you!

So that's it. New petcock is on order and I should be, well I mean my wife should be back in the saddle later this week.

I will make 1 final post to this thread once we have the bike back and are sure it is in working order.

Take Care,
Bob

Raven 1981 XJ650H Maxim
Dutch 1982 XJ1100J Maxim
Claire 1983 XJ550K Maxim
Suzy 1985 GS550L

[Nessism]

That check valve won't cause the fuel to overflow, but a leaking diapharagm will often allow raw fuel to flow backwards down the vacuum port and into the carbs causing a leak. Oh, and welcome to the GSR. You are welcome to hang out here and learn from the best. GS Suzuki's are superior bikes to your XJ's but any old bike is cool so we won't hold your choice against you.

[BassCliff]

Hi Mr. rwbersin,

Just in case I didn't point this out, Mr. bwringer has a nice article about Overflowing Carbs on my website. Check your "mega-welcome" for lots more fun tips and tricks. Welcome to the forum.


Thank you for your indulgence,

BassCliff

[rwbersin]

Post Mortem

So the bike is working fine for the moment; the carburator leak is fixed. It was the petcock, specifically a little rubber thingy that was behind a hard round plastic disk. This rubber piece was apparently factory pressed into a small hollow and was not replaceable. The rubber piece had turned to goo! This in turn had then effectively turned the inner working of the petcock into a "pump" which is what caused the carb to overfill. In hind sight I should have brought the pieces home with me and taken some pics. Sorry for not thinking ahead.

Thanks again for all of your help.
Bob