'83 GS450L - Sputter\muddy\nearly die during idle

[tom203]

Your right side is likely fine, but the left is letting too much gas in. Freely moving floats don't mean that they are controlling fuel flow- if o-ring leaks or needle seat is really worn, too much fuel will head to cylinder. This could easily foul the plug especially at idle.

[incarceration]

Here are some pictures of the 2 spark plugs from this morning

http://imageshack.us/g/1/10383606/

Do you suggest I buy new float needles, float needle seats, or can I just get new float needle seat O-rings?

[tom203]

When you get carbs off and fuel bowls too, I'd first invert them and compare the float height just in case you made an error here. Then inspect the needles and their seats for damage- obviously best to remove them- any score marks, etc? I'd replace the gasket (or o-ring) that sits at bottom of seat on general principles. In your case, I'd also test that floats actually float in gasoline to be safe.
After reassembling carbs, you can test them for overflow before reinstalling on bike by somehow hanging/holding them in their normal bike position and feeding them fuel from the tank (on prime position) or an auxillary tank.

[incarceration]

I just purchased 2 new float needles and seat assemblies as well as a sync tool.

Here's the needles and seat assembly I bought:

http://www.z1enterprises.com/ItemDetails.aspx?itemDescription=Float+Needle+Valve+Seat+Assembly&item=KL18-4671

I will update when they come in and I've replaced them and synced them