I just bought myself a '92 gs500.  I got a pretty alright deal on it, but it needs some work.  I'm pretty mechanically inclined (I have a ton of experience with cars) but I have never tackled a bike before, but I am trying very hard to learn.  This site has deff. given me a lot of info as far as what to do and where to look for a number of things I plan on doing in the near future, and hopefully in time I'll have some good input myself.  Anyway, the problem.....

I did search but I could not find the exact answer I was looking for.....
I pick this bike up the other day, I knew it needed a bit of T.L.C. when I purchase it and I'm more than willing to give it just that, but did not really expect this to happen.  When I get there to look at it the first time the bike is already warm so I test drive it and there are no problems.  I guess the bike had been sitting for the winter but the guy I got it from says it starts right up every time and that he has done a little bit of work to it to keep it running.  I decide that this is the bike for me and I pay the man and make arrangements to pick it up the next day.     The next day I show up and I start the bike cold.  It idles pretty rough, jumps rpm's pretty dramatically and I'm thinking that it's just due to sitting for a while, carbs need cleaning etc etc....   I let it run for about 5-10 mins and decide that I have to get moving because it looks like rain in the near future, and I'm 20 mins away from my house.       I take off and have no problems what so ever, however once I make it about 10 miles or so the bikes starts to stutter while I'm in motion and just looses all power.  I roll the throttle all the way back and just watch as my tach and speedo drop down to nothing and the bike stalls.  I pull over to the side of the road and it will not restart so I decide to  just wait for a few mins.  After about 5 mins I try to start it again and it starts right up.  I continue on for about another 10-15 minuets and all of a sudden the same exact thing happens, the bike stutters and coughs and bit and completely dies out, try to restart and nothing.  This time it takes more than 5 mins, probably about 15, to get it to restart but at least I get it going and take off.  5 minuets later I have the same problem again.  This time it takes another 10 minuets to start, but this time I get it home and park it safely in my garage where it has sat for a few days due to this being exam week for me.  Something else I noticed on the ride home is that there seems to be a bit of a lag in rolling on the throttle and actually accelerating sometimes.  Sometimes it just did not feel smooth, like I would give it gas and then a second later it would jerk a little bit and speed up, but other times it was right on.

I plan on doing all of the recommended maintenance for a bike in this conditiong, change fluids/plugs, clean carbs, clean gas gap, but I'm curious to find out if this has happened to any one else or if anyone has advice on what area I should focus on to take care of this specific problem.  Sorry to make my first post so long and drawn out I was just trying to cover all the details.  Thanks in advance for any help, but all is appreciated.
-Brendan

Sounds like she needs abit of PM to get her up and going. Do you know if the gas was on? The PO might have turned it off since the day before when you test rode it. Another thing could be that the bike has been sityting for so long that the gas has carmelized in the carbs and is clogging up the jets or simply your petcock took a crap and after a 15 minute spirited jaunt on the GS. the vacuum cuts out leaving you on the side of the road for about 5 minutes.

Clean,tune, and try again and don't forget to change the oil.

Thanks for the quick reply,

It's funny, it almost felt as if it were running out of gas when it stalled but I didn't think anything of it untill the second time it stalled out.  It took a bit longer to start again so I started trouble shooting and the petcock was set to reserve.  At that point I flipped it over to the on position and thought that that took care of the problem because as soon as I did that it started right up, but low and behold  5 mins down the road it died on me again. 

Yeah that's what I'm planning on doing, changing the oil, cleaning the carbs and all the fun stuff.  I'm really just trying to gauge to see if this problem is something that the regular maintenance can fix or if the problem is something more specific that i'd have to look into or take it to a shop.

Nope, with limited wrenching skills and reading here on the forum, you should be able to get most of it done yourself. I'm still iffy on the carbs and I've had my bike for over 10 years. Just get yourself a sixer, sometime to do it, and a place like the parking lot or manroom aka garage if you have on; and your all set.  :huh:

Tank vent (check the faq section, there's a good write-up on cleaning it out).

If the tank vent is the problem, 5 minutes at the side of the road will become no time if you pop the gas cap open when it stalls out. That's the part of your story that puts it at the top of my list.

http://gstwins.com/gsboard/index.php?topic=41061.0

Various possible iterations of actual problem with vacuum petcock (common, but it also gets the blame when it's not at fault if people don't look for other problems) and misrouted hoses, leaking vacuum hose to it, etc.

http://wiki.gstwins.com/index.php?n=Main.HoseRouting

Sometimes the upper vent hose gets clogged, mud wasps build a nest, etc.

If the problem is the vacuum hose to it or the vacuum petcock itself, putting it on "prime" will solve your running problems, though the prime passages are slightly smaller - but those don't seem to affect real running until you're in high-speed freeway mode well beyond most posted limits. But don't leave it on prime when you stop - any problem with the floats can lead to bad ju-ju and a crankcase full of gas.

I like the 5/16 polyurethane fuel hose from Cycle Recycle II - get 5 feet and replace them all - get two feet of 1/8 as well and you have a handy way to get stuff out of the carb drains and check your float height as well.

How much gas is in the tank? filling up solves more problems...the last half gallon or so is not really usable. I haven't used it (hadn't heard of it before this forum) but some folks seem to like "seafoam" as an additive, though others claim you have to engage in some more complex procedure for it do any good. Just plain "fresh gas" (drain out & run the old stuff through a lawnmower or whatever) solves lots of problems.

Use the drain screws on the carbs - get any watery crud that's sitting in the float bowls out.

When starting the GS cold, you need the choke. Depending on exterior temperature, you need the choke on for some period of time - since I don't like hanging around, I only warm up for a minute or two, and then ride off on partial choke. If you don't have a stop sign nearby, you can actually shut the choke off as soon as you start riding, but if you do need to stop "nearby" you'll want it on, or the bike will stall. In summer I'm fine at the stop 1/2 mile down the road, right now it drops dead if choke is off at that point.

DoD#i

Wow, great info, thank you so much.  These are all things I'm deff. going to do.  If it doesn't correct the problem it can't hurt the condition of the bike.  I do have have a fresh tank of premium gas, and I did drop some seafoam into it.  I know seafoam isn't the fix for problems and can tend to mask others but I figured if it helps me get home on this bike that's been sitting for a while that I don't know too much about, then it can't hurt too much, and I didn't put a lot of it in tank anyway.   Also I do know about using the choke and understand that this bike is "cold-blooded,"  but even with the choke on it was idling funny.  The actual clutch lever itself is kind of funny though, it doesn't glide easily kind of sticks a little but I'm assuming once it's oiled up it should be ok, plus I'm in the process of ordering a replacement left side handle.

So your saying as a quick fix I can just ride with it set on Prime?  Is this bad for the bike, what affects might it have?  I do want to fix the problem not just kind of by-pass it.  Any advice as far as that's concerned? 

I wish I had more info at this point but it has been raining just about all day everyday since I brought this thing home and haven't had a chance to take it out again, hopefully in the next day or two I will though.  Thanks so much for the fast info. I really appreciate it.   I'm trying to figure out exactly what I'm getting myself into so any more advice/insight is more than welcomed and greatly appreciated.
-Brendan

Read what I actually said. It only helps if the problem is a certain subset of things. What does or does not help leads towards certain diagnostic paths of what the problem might actually be.

If the problem is the tank vent, "prime" won't do a thing for it. Popping the gascap will help instantly if/when it dies again. Don't try that while riding, but you should see prompt response when you pop the cap and the bike starts right up again.

If the problem is the upper vent hose,  "prime" won't do a thing for it. Neither will popping the gascap. Clearing the blockage out of the hose helps.

Riding with it set to "prime" will let you see if the problem occurs still (see above) or not. If the problem goes away, look at vacuum to petcock and the petcock itself as possible culprits. However, there may be other problems - scott mentioned over in the forsale section that he changed out two petcocks and his actual problem was a torn rubber carb boot.

If the problem is the petcock not providing fuel due to either a common failure mode of the petcock, or a leaking/disconnected vacuum line to the petcock, "prime" will help - just remember to turn it to "on" when you park the bike, to avoid the only bad thing that can happen due to running it on prime (other than running out of fuel at 85 mph, and the cure for that is to stick to the speed limit, or choose a road other than a high-speed freeway, at least until you sort that out, if that is the problem).

<edit-add> Premium gas is a waste of money on a GS. Plain old unleaded regular is all it needs or wants, unless you've been shaving the heads or something like that to raise compression.

Ahhh, ok I understand you better now, sorry.  I don't know what I was thinking the first time I read that through.   The premium gas is just a habit from the car I drive, but the first time I filled it up, I wasn't sure what kind of gas was actually in the tank already so I figured it couldn't hurt.     Thanks so much again for all of your help man.  I'll start on doing all of that hopefully tomorrow if the weather clears up at all and see what results I can come up with.