Took the GS for a ride today and got to the end of my street and it stalled so I turned the petcock to Reserve and it was fine. Went and filled it up and accidentally left it on Res. Got to my destination and it stalled before I could turn it off.
Went to start it back up and it would idle at like ~750rpm and as soon as you give it any throttle it just died. I let it idle for a minute or two and the idle climbed to around 3000rpm (I had put the petcock back on ON) and went a whole 4 miles and when I came to a stop it died again. Crank crank crank and nothing. Reached down and turned it to PRI and it started up and did the same thing, idled at ~750rpm and eventually went to 3000rpm at idle. I was able to ride it for a few miles and it died again and wouldn't start before the battery died so I had to park it at my buddy's work.
The only "mods" to the bike are a lunchbox K&N installed yesterday and a YZF250 exhaust silencer installed by the previous owner (don't ask, the GS had a turbo on it before).

What could be the culprit? After i installed the K&N I noticed that the bike is a lot more peppier and throttle response is amazing. One thing I forgot about was the hose at the top of the valve cover that goes into the stock airbox. What do I do with it once the K&N is on?
I was doing some reading and saw something about a vacuum hose to the petcock. I don't recall seeing this. My bike is an '89

Rejet ? K&N and pipe ... big change in jetting needed.
BTW the super low idle and the hanging high idle as well as refusal to start can all be lean ... yes, in rare situations it can also seriously lose Rpm when lean. The sign of being rich @ idle is not the low rpm Idle, its dropping below the set idle rpm and climbing back to the idle rpm when you blip the throttle.
You're lean my friend, very very very Lindsay Lohan lean.
Cool.
Buddha.

So should I throw the stock airbox back in until I can rejet it and such?

I also have a Vance & Hines system I need to install.

Yea you're likely to really make it worse with the pipe.
I'd run the airbox till rejet, and do K&N and pipe and jet all @ the same time. Or, jet it and pipe it before riding it again.
You can jet it, dont need no steenkin shop, you pulled the airbox out right, that is 90% right there. Another 2 mins and you'd ahve the carbs out ...
What year is the bike - the jets depend on that.
Cool.
Buddha.

It's an 89. I took out the carbs before to clean them when I first got it.

You sell the proper jets right? Let me know a price for the ones I need for an 89 GS500 with a V&H pipe and K&N filter Thank you sir, you are definitely one of the most helpful people on here.

UPDATE.

I put the new jets in and put it all back together (minus battery and air filter)
Jumped it and it started up but idled really low. Gave it some gas and it died so I started it up and it did the same thing then backfired out the carb. Then it just cranked and cranked and cranked. Would not start again. I am at my wits end here as to what is going on.
I'm about to just drop it off at the bike shop and say fux it and fix it.

What am I doing wrong here? Mixing up a hose when putting it back together? 

Are you sure there is gas in the carbs? You need to set the petcock to prime id it hasn't had gas in it recently.

yes the petcock is set to prime

Carb Vent hose clogged/kinked ? Why no air filter ?
Cool.
buddha.

Quote from: The Buddha on May 31, 2011, 08:51:19 PM
Carb Vent hose clogged/kinked ? Why no air filter ?
Cool.
buddha.

The carb vent hose is the hose on top, between the 2 carbs, right? The feed goes on the bottom? And no air filter because I just wanted to see if the damn thing would run and it wouldn't.

Assuming your compression is ok, that leaves spark and fuel. Spark is easy to test so that's what I would check next (even though it's probably fine). Either your idle is set way too low (worth checking into) or your pilot jet is somehow dirty already.

Did you check for gas in the carbs? Just because it's on prime, doesn't guarantee that there is gas.

Rust in the tank and flow from the petcocks as well as tank vent are all suspects too.
Cool.
Buddha.

yeh when you left it on res it could have sucked in alot rust. take apart the carbs and check it out

It was PRI which should be unrestricted flow, right? 
i mean should i take the tank petcock out and blow it out? the tank doesnt look all THAT bad inside

Bringing it to the shop next week unless I can fix it.

Quote from: Garrett on June 02, 2011, 12:19:03 PM
Bringing it to the shop next week unless I can fix it.

K we do this the messy way.

Open the drain screw with the petcock in prime. Should flow like a river.
If not, remove the line from the petcock to the carbs. Flow line a river ... If not ...
Remove the line to the frame petcock. Flow like a river ... if not, then the tank petcock is the first culprit.

Cool.
Buddha.

I feel like a dickhead, the drain screw is on the bottom of the carbs, correct? 
When I put the petcock on RES I pulled the feedline off the petcock from the tank and got covered in fuel.

Quote from: Garrett on June 01, 2011, 09:22:03 AM
It was PRI which should be unrestricted flow, right? 
i mean should i take the tank petcock out and blow it out? the tank doesnt look all THAT bad inside

yes please check all possible suspects.  the stuff buddha mentioned and any other component invovled in the fuel/air delivery system

I am wondering if I crossed something when I put it back together.

is this correct? Pic is from ebay.



Where does the vacuum tube for the petcock go? On the side of the one of the carbs, right?