I took the '91 GS500e out for a ride this morning and when I got close to 80 mph it started to stumble as if it was out of gas.  I was able to pull off the freeway and the Highway Patrol was cool enough not to give me a ticket. Even said it was ok for my son to come and get me in the truck. I was able to restart it after a couple of minutes.  I was thinking that the mains are not big enough to haul my fat a$$ at full throttle.
Sound correct or should I look at something else. 
I'm getting ready to order some gaskets for an oil leak at the crankcase so I figured maybe a couple of new main jets on the stock bike might be in order too.  It runs great at low to midrange.  As a matter of fact we tokk it out for a 100 mile canyon run right after.

Try a search for "fuel starvation"

Basically, though, at full throttle the bike drains the float bowls of the carbs, which means eventually it sucks no fuel, sputters, and dies. I forget the remedy, though.

Possible overheating problem?

I had this happen to me about a week ago. I just let it sit for a few minutes and it started again.

Part of the cure would be not to go high speed for an extended time, especially on hot days.

I read through some of the posts on this problem and did not see if anybody had gone with a bigger main so I'll try that.
I read elsewhere that at full throttle the main jet could be the culprit.  They're cheap so what the heck.

I think this is a common problem with the older GS models.
A larger main is not going to solve it.
It's fuel starvation problem.  Not enough fuel going into the
carbs.  I don't know what the solution is.

Quote from: mp183 on January 29, 2006, 05:34:15 PM
I think this is a common problem with the older GS models.
A larger main is not going to solve it.
It's fuel starvation problem.  Not enough fuel going into the
carbs.  I don't know what the solution is.

I think your right on the mains.  I talked to my motorcycle mechanic and he said to mess with the floats for one thing.  Maybe the petcock is the culprit.
It sounds like since this is a common problem that the petcock could be it.  If I could find a better aftermarket that would be great.   Also really the bike burns more fuel at full throttle than is allowed to enter the float bowl thus -out of gas.  Now how to solve that is the question.
Besides that and a fixable oil leak this is a sweet bike.

Quote from: bubba zanetti on January 29, 2006, 02:27:29 PM
I had this happen to me about a week ago. I just let it sit for a few minutes and it started again.

Part of the cure would be not to go high speed for an extended time, especially on hot days.

Bubba, It's summer where YOU are but it's friggin' winter here
Well kinda, it's not too cold here in Southern California.

Have you tried running with the petcock in prime?

Have you coated your gas tank lately? You may have a gas tank venting problem, which will definetely cause the bike to "run out of gas". Can be caused by rust in the tank as well, which can be clogging the air vent, or the fuel pickup.

Why did a cop want to give you a ticket for your bike dying and being on the side of the road?

-Patrick

whoa whoa slow down, what setup do you have for intake and exhaust.  dont go messing with the jetting right off the bat, 80mph and up there tends to be Vacume issues with the Frame mounted petcock, i dont even run the vacume line anymore i switch to prime and run and havent had a problem with starvation since. Im running a hindle header with a Yosh can, and still filterless but havent been riding the gs much lately. 150 mains, 40 pilots 2 washers under the needle. if your pulling 80 without much of a fuss other then long term running, i dont think jets are your issue.

Quote from: Blueknyt on January 29, 2006, 07:52:15 PM
whoa whoa slow down, what setup do you have for intake and exhaust.  dont go messing with the jetting right off the bat, 80mph and up there tends to be Vacume issues with the Frame mounted petcock, i dont even run the vacume line anymore i switch to prime and run and havent had a problem with starvation since. Im running a hindle header with a Yosh can, and still filterless but havent been riding the gs much lately. 150 mains, 40 pilots 2 washers under the needle. if your pulling 80 without much of a fuss other then long term running, i dont think jets are your issue.

The bike is stock all around.  I had heard of running on prime and that seems like it would work but when you shut off the engine it seems like it might continue to let gas in the carbs and possible leak into the crankcase.  I will look into vacume next or as I said maybe the petcock is old and clogged.
*************
"Why did a cop want to give you a ticket for your bike dying and being on the side of the road?

-Patrick"
I have heard that a cop can give you a ticket for about anything and dieing on the road would be one of those things but I did get off to the side so I was fine. Just paranoid I suppose

it can do just that if left in prime and your float needles arent doing thier jobs. the pickup tube on the tank valve in mine was cut flush by prev owner for the track. he ran the hoses to a T and then to the carbs.  i effectively have no sep reserve or on positions. Prime works as it should. for a long time will running the vacume petcock, a few mins into 80mph it would starve for fuel.  switching to prime solved that. the diaphram started to leak in the petcock sucking fuel into theleft carb, so i plugged the line and just switch from run/res (fuel off without vacume supply) to Prime (On )  prime supplies all the fuel i need with any spirited riding i have done. just switch to prime when you run and back to on when you stop

When I run on the highway (high speed and rpms ) I must run on prime.  If I run on.....ON it will sputter and die.  Here is a thread from before discussing the issue.....

http://gstwins.com/gsboard/index.php?topic=19375.0

Quote from: xtalman on January 29, 2006, 07:29:56 PM
Have you tried running with the petcock in prime?

Quote from: greennug on January 30, 2006, 06:04:02 PM
When I run on the highway (high speed and rpms ) I must run on prime. If I run on.....ON it will sputter and die. Here is a thread from before discussing the issue.....

http://gstwins.com/gsboard/index.php?topic=19375.0

Sorry bout the double post... For some reason couldn't edit first one.