I bought my first bike a few weeks ago... a '91 Gs500. Figured I'd get something a little older to learn on in case I did drop it. Well I rode it for probably 50 miles with no problems, then all of the sudden the bike started sputtering and eventually cut off. I switched the petcock over to reserve and then made it approximately two miles and it started sputtering again. I was able to limp home by pulling over every couple of miles and switching the petcock back and forth from run/reserve.

So.. I figured the carbs might have been a little gummed up, so I checked them and also checked the valve clearance while I had the bike apart. Both were fine. Now when I put the bike back together, as soon as I hit the ignition switch the bike immediately red lined. I went back in and loosened up the throttle cable, and the bike is still red lining. I have plenty of play in the cable and have it a loose as it will go where it connects to the carb. I don't know what else to check? I noticed there is about a 1/2 inch gap between the idle adjustment screw (with it up as far as it will go) and the spring that the throttle cable hooks to on the carbs. Shouldn't these be making contact? Any Ideas?

that screw should make contact. if your screw is all the way in and its still not touching the idle "lever" ill call it for lack of better terms, then your idle lever is stuck

If it was just revving some, I would say choke cable or an air leak.  But it sounds like you have the throttle cable routed wrong or hooked up wrong.

I would just take it apart and reassemble it.  Take the carbs off the bike and get the throttle cables hooked up to it so it works correctly, put the carbs back in the bike and do the same thing.

Might be worth checking your tank cap is venting,won`t cause the high revving but may cause fuel starvation,i`d check your slides and needles are seating too.

Yeah, I checked the gas cap per the sticky on here, and it appears to be working correctly. I'm wondering if it's petcock... I'm going to try an run it on prime if I get this throttle issue resolved.

I removed the throttle cable from the carbs again, and as soon as I removed it the spring went all the way down to the idle adjustment screw, so it doesn't appear to be stuck. It looks as if there is not enough actual cable coming out of the threaded part that connects to the carb. The cable is routed correctly and there is plenty of slack, just not enough actual cable from the threaded part down?

Quote from: deaconsfan on August 11, 2010, 06:18:52 PM
Yeah, I checked the gas cap per the sticky on here, and it appears to be working correctly. I'm wondering if it's petcock... I'm going to try an run it on prime if I get this throttle issue resolved.

I removed the throttle cable from the carbs again, and as soon as I removed it the spring went all the way down to the idle adjustment screw, so it doesn't appear to be stuck. It looks as if there is not enough actual cable coming out of the threaded part that connects to the carb. The cable is routed correctly and there is plenty of slack, just not enough actual cable from the threaded part down?

The cable is either routed incorrectly or stuck somewhere.  My money is on it being jammed up inside the throttle grip.

Sounds like your throttle was working OK when you first rode it, so the cable was long enough then. Then you worked on the carbs, now the cable is pulling the carb butterfly open.
I think the problem is in the nut that connects the handlebars to the seat.
You need to strip and reasssemble each part of the throttle stuff from twistgrip to carb until its right. I'd suggest starting at the twistgrip as something may have moved up there while the tension was off the cable??
Good luck!

Well I just ordered a new throttle cable since the one I had was frayed pretty bad and looked like it was ready to break any second. How involved is installing the new cable to the grip?