I have a couple of problems with my 89. First is the amount of gas flow is not enough to keep the bike running at more than an idle. I have a jet kit, high flow jardine exhaust, and a k/n pod filter. I did make the gas lines a bit longer.  Any thoughts I was have been thinking about just replacing the petcock.

The second is the clutch, when I would ride the bike and go through the gears fast the clutch would just go out, like the clutch cable was not attached to anything. It would come back after a minute or some as long as I didn't go through the gears fast again. Now the clutch cover has a circle that is being pushed out from the inside, this is so bad that the metal is cracking , and has pushed a little part out. I have bought a replacement clutch cover. And plan to try and fix but I haven't taken it apart yet. Any thought as what this might be.

What size jets are you running?

Don't remember, it ran great for awhile now there is a air bubble in the gas line to the carb and the gas barely comes out of petcock. I checked the one on tank, and that one seems to have a lot of gas coming out. But then I read on here that they are know for this problem and that he put a different one on for racing.

I was just going to put two new ones on but was.wondering if I would just have this problem again.

I had this problem as well with my '89, air in the gas lines, also fuel starvation at highway speeds. I bought the CFR250 vacuum-less petcock setup, and routed the fuel exit line (to carbs, from petcock), under the little bit of the frame crossmember. I also took apart my gas cap and cleaned out the vent holes (great how-to in the FAQ section), and lubricated everything.  Since then I haven't had any issues. The gas doesn't seem to fill up the tubes completely, but I've never had a starvation or idle issue, unless I forgot to turn on the petcock 

Quote from: knowles on October 25, 2011, 09:11:46 PM
The second is the clutch, when I would ride the bike and go through the gears fast the clutch would just go out, like the clutch cable was not attached to anything.  It would come back after a minute or some as long as I didn't go through the gears fast again.  Now the clutch cover has a circle that is being pushed out from the inside, this is so bad that the metal is cracking, and has pushed a little part out.  I have bought a replacement clutch cover.   And plan to try and fix but I haven't taken it apart yet.   Any thought as what this might be.

Metal fatigue.  Also, check the clutch actuating arm, I've had mine rust away and break apart while riding.

Ok I'm going to try and clean out the gas cap first, when you buy a different pet rock that doesn't have a vac line what do you to the vac line coming off the Carbs?

There is a vacuum cap that goes from the petcock to the carbs, follow it back and put a little rubber cap on it.
Details here:
http://gstwins.com/gsboard/index.php?topic=56352.msg648914#msg648914

Also sometimes you can get so much crap flying off the chain that it clogs the clutch arm and pushrod, check there's not a load of caked on grease and dirt under the sprocket cover

Quote from: knowles on October 25, 2011, 10:08:27 PM
Don't remember, it ran great for awhile now there is a air bubble in the gas line to the carb and the gas barely comes out of petcock. I checked the one on tank, and that one seems to have a lot of gas coming out. But then I read on here that they are know for this problem and that he put a different one on for racing.

Seems everyone is eager to always blame the petcocks. While they can go bad, of all the GS500's around here I think only one had a problem with an old one and put on a replacement and all is OK. No one else has a problem. I wouldn't jump into re-jetting or  other things as a cure for poor fuel flow.
You did change fuel lines. It worked before, now it doesn't. Likely problems are two:
1. Vacuum line not connected well or pinched
2. Fuel lines pinched.

The space for those  lines between frame and air box is really tight. Very easy to pinch a line or put a sharp bend in it.

I'm for not changing things unless necessary and you really know that needs replacing with something else. I don't like to blindly start doing things.

If you suspect the fuel petcock - put it on PRIME. That bypasses the vacuum valve completely. If still no gas - then you've got pinched lines. If you do get gas - possible the main line was pinched and reserve was not or the  rubber diaphragm is bad so just get another petcock off ebay from someone reliable like Pinwall (they show videos of a bike before they break it down so you know things were working). You could run a fuel line from the tank to the carbs bypassing the petcock - as a test - to see if the petcock is bad.

If you suspect the fuel cap, then leave the fuel cap open and see what happens.

Do you really know it is lack of fuel? Could you have air leaks or restricted air flow through the air filter?

New kn air filter (lunch box I think their calling them) I put new lines on it except the one to the cabs then replaced that one when I redid the Carbs. It ran great then I had trouble with the bike not starting. I would turn the key on and the only thing that would happen the neutral light and oil light would come on, not the head and tail lights. Looking over the wiring harness I could aalnumber of places that it could be so I replaced the whole wiring harnes. Everything electrical works now. But I took it on a ride to get oil do to a oil change and on the way back the bike would speed up then slow down I managed to get it home. I had it running on the center stand and I can see the fuel line with a bubble in it when I give it more gas. It will sit and ideal all day. I don't see a difference in the gas flow no matter what I put the petcock on.

Do you have gas in the tank?

I once got the lines from the fuel pickup to the petcock switched around. Couldn't figure out why the bike wouldn't run, even though there was gas and I was on the res position.

Will double check.

BTW... In my case, it was because the fuel pickup was actually installed backwards, so carefully double check that. Double check the hose routing for the petcock as well; the correct routing is very unintuitive, and easy to get wrong. The diagrams are confusing.