1982 gs 450 erratic idle/ hanging idle

[Dlines]

I have a 1982 gs 450. I got it recently it had erratic idle and just did not run great when riding. I adjusted the valves they are now in spec. I took the carbs completely apart cleaned every part sprayed all the ports used compressed air and put back together and bench synched. I replaced the intake o rings with OEM new ones. The intake boots were very pliable. They were OEM Suzuki. I cleaned them up and put some rtv ultra black around the outside as a extra precaution ( though there was really no visible cracks or deformities). New spark plugs. I fired it up and it idled very high. The left side exhaust would backfire everytime I shut it off. I checked the plug and it was very lean the bike idle would raise and fall on its own for no apparent reason. I backed the idle down to about 1200 rpm using the adjustment knob underneath carbs. I hooked up my manometer and the carbs were pretty much spot on from my bench synch. I backed the fuel mixture screws out like a 1/8 turn. And this is what I’m left with. It’s definitely better but still seems to be hanging a bit. Or maybe I’m paranoid maybe this is how it should be? It seems like every day I go out to the bike it seems to run different with different outdoor temps and such. Just thought I would ask some knowledgeable people about this cause I don’t know what else to do lol. Thanks.

[Gorminrider]

Hi Dlines..it's so hard to tell through a computer screen but it does sound like a lean condition...assuming you did everything right in the carbs-taking everything possible apart and checking it, (ie:When you had the carbs out did you check that the float needles were thoroughly clean including the filter screens and that the needles are actually spring loaded? did you get the vacuum diaphragm in the right place and sealing did you carefully remove the jets and carefully clean the tiny holes and blow through every passage...etc etc It's not unusual to do this all more than once, I'm afraid, because restoring flow in one place can shift crapola from another)
- a quarter turn of an idle screw doesn't mean much. turn it out a 1/4 at a time until the cylinder runs best. then in a 1/4. If there's no diff when you wind it slowly in and out, the passage is blocked, the jets are dirty inside the carb.
- you might try pulling the enricher/"choke" out and see if that helps...that would indicate that there's not enough fuel and might save going further afield to ignition problems...naturally it'll affect the good side too but that's ok temporarily...turn down the idle

-I see you have changed the intake boots. There's no need to add rtv anywhere on these bikes except as a temporary fix. Often, trouble comes from " the last thing you did" and "lean" on one cylinder suggests air leak
another obvious source of an airleak is the vacuum tube that activates the petcock but you say right side is ok so that wouldn't be it.

-Check the fuel level of the carburettors...a simple clear tube from the bowl drain can do this....perhaps the floats are not set right

-if nothing about fuel works, you might suspect your ignition. start at the spark plug caps and the wires that go to them from coils (-the caps come apart and there's tiny springs and a resistor thing in there...search "spark plug caps" or the like here and at Bass Cliff's-tons of stuff there.Lots of it applies to your bike even if it seems to be about 4s BikeCliff's Website)
There is an advance mechanism -it may be mechanical or it may be electronic in your '82, -look this up here with search and check the sensors and the connections and the wires very carefully.if you have a mechanical type check that the weights are free to move.

here's a real shop manual for the 450s. You'll need this anyways

GS450 Official Service Manual PDF