I recently purchased a '90 GS-500 with about 19,000 miles on it. The first thing I did was a quick cleaning of the bottom of the carbs. It started up and ran fine without the filter.  Later on, I put the stock filter on and it ran better. Then I tried to start it a short while later and it was like it couldnt rev up.... it would idle at 1200 then it would work fine if i could get it to rev over 2500 rpms.... once i got it over 2500, it would idle at 3,000 unless i hit the kill switch momentarily to drop the rpms to 1200 then it would idle at 1200....or if its being stupid it will just stall. So since then I have:
*completely cleaned the carbs all the way through. Still had the same problem.
*Since the stock filter was pretty plugged looking, I bought a K&N lunchbox and rejetted to 140, no washers... Deffinately improved power... didnt solve the problem
*Set the float levels to within spec.... didnt help.
*Bought a rebuild kit for the left carb because somtimes the carb bowl would overflow, so i thought it might be flooding out and not wanting to work at the low rpms.... fixed the overfilling... didnt fix the bad low rpm problem.

AHHHH Ive had my carbs apart like 20 times, and Im running out of Ideas... maybe like a vacuum problem? or the slider thingeys sticking? Once I can get it above 2500, It runs awesome... and it dosent give me the problem all the time. I really want to get this thing running reliably before school starts, so i can take it too school.

Thanks,
Weston

Make sure you have plenty of gas in the tank.GS's hate quarter full tanks!

*full gas tank... didnt bog, but still doesnt run right.... I went for a real short ride tonight, and as i was riding the engine stalled.  wouldnt start. so i started pushing it home, and got tired so i tried to start it....i started and ran, so i gunned it, and it stalled again, but i managed to coast into my driveway.

Please help, I am getting frustrated.

Weston

OK vent in the tank. Tank petcock set to open ... vacuum line to frame petcock OK ... jets clogged
Now in 20 times ... forget it, send me the carbs ... you have pipe or not ... how did you select 140 mains with K&N.
Cool.
Buddha.

Hey... I know its been awhile, but thanks for the help. I finally got her running right. I think it was several different problems including low fuel, leaky carb float, wrongly adjusted idle, and most importantly a bad petcock. So I just ran the reserve line straight into the carbs, which I realise isnt the best, but it works.

So now, whenever I take it out it leaves oil spots on the ground where i park it. I think its leaking out of the left side cover, but im not sure, theres oil all over the engine.. though its not losing enough to show on the dipstick. How hard would it be to change the side cover gasket? I assume I would have to drain my nice clean oil?

It has 20,000 miles, how long do these motors last typically? I assume its probably about due for a valve adjustment. i looked down the intake towards the valves when i had the carbs off, one side looked cleaner than the other... im guessing thats probably not a good sign.

oh, and no pipe as of yet, but i plan to add one before too long.

Weston