Gs450 converted to 500cc. Idling issue

[Shaun6691]

Hey guys, so I converted my gs450 to 500cc's using a gs500 jugs and pistons and now I can't get it to idle down low. It will idle high (2200 rpm) and rev up fine with good power but if you let it idle for very long, the idle drops and then dies of you do not give it gas immediately. When the idle starts to drop off / it runs rough and once it dies, you cannot start it up without waiting several minutes due to the plugs fouling. The idle screw adjustment does nothing as far as dropping idle to where it should be. It has new coils and wires. 40 pilot jets. Carbs synced and thoroughly cleaned. Valves are adjusted. Timing set to stock.
My thoughts are that now the compression ratio is changed (not sure if its higher or lower now) that the timing needs to be adjusted from stock. Thoughts? No word yet at the gs forum. The bike is an 82 gs450 with pods and a 2-1 exhaust. Battery charges just fine. Help!

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[Scooter trash]

Back off the idle adjust screws, so the slides seat. There should be some slack in the throttle cables, and both slides should hit bottom at the same time. You won't be able to adjust idle mixture unless they are the same height. Make sure the angle cut away of the slide, is toward the air cleaner. A tight cable on the top of the carb adjustment will keep it from seating down. Are the idle air screws about 1 1/2 to 2 turns out from a slight seating?