Quote from: jeremy_nash on April 15, 2009, 05:26:33 PM
you did remember to turn the petcock on on the tank back on after you reistalled the tank didnt you?  if thats not it, you may not have as much fuel in it as you think.  try running a gas line directly from the tank, to the carbs, and cap the other one at the petcock, and try that.  if it runs like that, it would indicate a petcock problem

yeah that's what i did. i actually just removed the petcock completely and ran a line directly from the tank to the carbs. i capped off the reserve on the tank and the vacuum port on the carbs. it runs fine in that configuration, so i'm quite certain that something is wrong with the petcock. how much do i need a petcock if it runs without?

Quote from: dleemiller on April 15, 2009, 05:49:06 PM

Quote from: jeremy_nash on April 15, 2009, 05:26:33 PM
you did remember to turn the petcock on on the tank back on after you reistalled the tank didnt you?  if thats not it, you may not have as much fuel in it as you think.  try running a gas line directly from the tank, to the carbs, and cap the other one at the petcock, and try that.  if it runs like that, it would indicate a petcock problem

yeah that's what i did. i actually just removed the petcock completely and ran a line directly from the tank to the carbs. i capped off the reserve on the tank and the vacuum port on the carbs. it runs fine in that configuration, so i'm quite certain that something is wrong with the petcock. how much do i need a petcock if it runs without?

You need it. If you don't, gas will continue to flow to the carbs when the bike is off and could cause trouble. You could end up with a big mess like a crank case full of gas if anything ever goes wrong with your floats. Even tiny float height problems could cause a massive headache. My friend lent me his KLR250 one day that had been sitting with the petcock on reserve for a couple of weeks and I found out on the freeway that pretty much all the gas in the tank had slowly leaked from the carbs and evaporated, leaving me with so little gas I only got about 14 miles before it was time to start pushing. You'll also want a petcock so you can make use of the fuel reserve instead of just running all the way out of gas. I know you might now think that you'll just keep track of all the mileage and never run the tank down, but there will be some day that you'll be distracted and not fill the tank up all the way and then ride really hard and then try to make it that extra couple of miles where you know you've almost got no gas to make it to the cheaper gas station and then end up pushing the bike. Trust me, pushing my friend's KLR250 3/4 of a mile to the gas station took about a half hour and was very tiring and that bike weighs more than 100 pounds less than a GS, you don't want to push the GS if you can possibly avoid it. You need a petcock, it is a really handy thing.

Quote from: fred on April 15, 2009, 07:11:25 PM

Quote from: dleemiller on April 15, 2009, 05:49:06 PM

Quote from: jeremy_nash on April 15, 2009, 05:26:33 PM
you did remember to turn the petcock on on the tank back on after you reistalled the tank didnt you?  if thats not it, you may not have as much fuel in it as you think.  try running a gas line directly from the tank, to the carbs, and cap the other one at the petcock, and try that.  if it runs like that, it would indicate a petcock problem

yeah that's what i did. i actually just removed the petcock completely and ran a line directly from the tank to the carbs. i capped off the reserve on the tank and the vacuum port on the carbs. it runs fine in that configuration, so i'm quite certain that something is wrong with the petcock. how much do i need a petcock if it runs without?

You need it. If you don't, gas will continue to flow to the carbs when the bike is off and could cause trouble. You could end up with a big mess like a crank case full of gas if anything ever goes wrong with your floats. Even tiny float height problems could cause a massive headache. My friend lent me his KLR250 one day that had been sitting with the petcock on reserve for a couple of weeks and I found out on the freeway that pretty much all the gas in the tank had slowly leaked from the carbs and evaporated, leaving me with so little gas I only got about 14 miles before it was time to start pushing. You'll also want a petcock so you can make use of the fuel reserve instead of just running all the way out of gas. I know you might now think that you'll just keep track of all the mileage and never run the tank down, but there will be some day that you'll be distracted and not fill the tank up all the way and then ride really hard and then try to make it that extra couple of miles where you know you've almost got no gas to make it to the cheaper gas station and then end up pushing the bike. Trust me, pushing my friend's KLR250 3/4 of a mile to the gas station took about a half hour and was very tiring and that bike weighs more than 100 pounds less than a GS, you don't want to push the GS if you can possibly avoid it. You need a petcock, it is a really handy thing.

thanks for the info. its only a $50 part, so i think i'll just go ahead and order a new one.

something has been wrong with this bike since i got it and i think the petcock was it. it wouldn't idle correctly and i was totally confused when i pulled apart the carbs to find that they were spotless... just before it stopped working all together it started surging really badly.

on to fixing the tach, kill switch and replacing the front springs! 

ok i'm still having problems  .. here's the state of things.

* only getting fuel into the left float bowl
* carbs have been fully cleaned, no blockages found and were pretty spotless when i opened them up
* brand new petcock is installed
* bike gets gas to both carbs and fires right up when i bypass the petcock and run the tank line directly to the carbs



i'm really confused....what would cause the bike to only pull gas into 1 carb? the right carb (side without vacuum hose attached) is almost bone dry and gas readily drips out of the other side.

That's kinda odd.

Three thoughts:
1-are your hoses routed properly?
  http://gstwin.com/images/how_to/fuel%20hose/www_gs500_de_HoseRouting.jpg

2- floats not set right

3- some blockage in one of your hoses

i know all the hoses are connected right... except maybe the vacuum line. ive checked that picture several times, but i can't see where the vacuum hose goes and there wasn't one connected before i got a new petcock.

it connects to the inside left carb correct?


on a side note, are you an atlanta rider? i live in the city, so i was just curious.

Yes, inside of left carb to petcock. 

Edit:  Didn't read post all the way to the end.  I'm in Lawrenceville actually.  Will be heading towards the city tomorrow.  What part of town you in.

if my bike had been converted to a gravity feed, there should be something plugged right? maybe it's not getting any vacuum... if all else fails, i'm going to buy a metal valve and take out the petcock. do you know off hand if the gas hoses 1/2" or 3/8"?

If you convert to manual petcock, you'd install a vacuum cap to the left side carb.  Same place the vacuum hose goes now.  I'm using 5/16" I.D. X 7/16" O.D. clear polyurethane hose.  I like the clear hose cause I can always see if the fuel is getting to the carbs and if there's any rust or debris coming from the tank.

Edit:  You can check the vacuum while the engine is running by pulling the vacuum line from the petcock and put your finger over the line to see if you can feel any suction.

If I remember correctly its actually some mm size. 1/4 or 3/8 will work though. 3/8 is a bit loose but will be fine as long as you tighten the hose clamp down tight and 1/4 is particulary tight and can be a pain to get on but would probably hold fine without a hose clamp if one were so inclined.

Quote from: woodchuck5515 on April 26, 2009, 06:24:13 PM
If I remember correctly its actually some mm size. 1/4 or 3/8 will work though. 3/8 is a bit loose but will be fine as long as you tighten the hose clamp down tight and 1/4 is particulary tight and can be a pain to get on but would probably hold fine without a hose clamp if one were so inclined.

IMHO, I think the 5/16" is a good compromise. It seems to fit just right.
Didn't like the 1/4" hose cause of the same issue of being a PITA to remove and I'm always tinkering around so didn't want to mess with that.

Ya now that I think about it I think that 5/16 might be the correct size it can just be a pain to find sometimes. I don't believe any of my local businesses stock it but if one does near you then its the better choice. Its just not worth making a special online order just for that.

Quote from: ATLRIDER on April 26, 2009, 06:23:42 PM
If you convert to manual petcock, you'd install a vacuum cap to the left side carb.  Same place the vacuum hose goes now.  I'm using 5/16" I.D. X 7/16" O.D. clear polyurethane hose.  I like the clear hose cause I can always see if the fuel is getting to the carbs and if there's any rust or debris coming from the tank.

Edit:  You can check the vacuum while the engine is running by pulling the vacuum line from the petcock and put your finger over the line to see if you can feel any suction.

ah good point. ill give that a shot first and see if im getting any pull. i think my bike was converted to manual because when i got it there was no vacuum line attached...but there also wasn't a cap on the inside left carb.

unless i'm just totally picking the wrong spot to attach.. i know the vacuum ports on the top of the left and right carbs (by the black plastic tops) that i used to check the vacuum. both of those are capped, but i thought from the picture i was another spot on the inside.


i live close to midtown in an apartment complex just off of peachtree and collier road if you know where that is.

Quote from: woodchuck5515 on April 26, 2009, 06:34:57 PM
Ya now that I think about it I think that 5/16 might be the correct size it can just be a pain to find sometimes. I don't believe any of my local businesses stock it but if one does near you then its the better choice. Its just not worth making a special online order just for that.

If you have a Cycle Gear near you, they'll have it.  It's where I got it. 

Quote from: dleemiller on April 26, 2009, 06:36:29 PMah good point. ill give that a shot first and see if im getting any pull. i think my bike was converted to manual because when i got it there was no vacuum line attached...but there also wasn't a cap on the inside left carb.

unless i'm just totally picking the wrong spot to attach.. i know the vacuum ports on the top of the left and right carbs (by the black plastic tops) that i used to check the vacuum. both of those are capped, but i thought from the picture i was another spot on the inside.


i live close to midtown in an apartment complex just off of peachtree and collier road if you know where that is.

If there wasn't a cap on the left carb (not top plastic of carb, below there should be a metal nipple) the engine would have a pretty good vacuum leak and would probably run kinda crappy.  Also, if you ever tried to sync the carbs with a leak that big, it'd be way off.

Quote from: ATLRIDER on April 26, 2009, 06:42:02 PM

Quote from: woodchuck5515 on April 26, 2009, 06:34:57 PM
Ya now that I think about it I think that 5/16 might be the correct size it can just be a pain to find sometimes. I don't believe any of my local businesses stock it but if one does near you then its the better choice. Its just not worth making a special online order just for that.

If you have a Cycle Gear near you, they'll have it.  It's where I got it. 

Well only kinda near. Its about 45min to an hour away but i've been meaning to go there to check out some new riding gear (mostly pants) in person since my couple of local dealers hardly stock anything and one didn't even have a single pair of pants