Repairing my 1980 GS450

[apopleptic]

so yesterday I tried starting my bike with a jumper pack since my battery is a goner.
I had to spray a little starting fluid and that got it to turn over.
I got it going and then after running it for about 10~15 minutes I shut her down.
Afterwards I checked the plugs and they were wet and smelled like starter fluid, or gas.
I wiped them down and brushed them off and put them back in but it wouldn't start.
I sprayed just a small amount of starter fluid into the airbox again and the bike backfired through the carbs and the air filter caught on fire and started smoking.
Now, I'm a little hesitant to try again.
The airbox is stock, the airbox and carb boots have been replaced. Carb was fully rebuilt last riding season with all orings replaced.
exhaust is stock except the bar underneath that connects the two pipes has been replaced.
pilot air screws were set to 2.5 turns out, but I have put them to 1.5 turns out because of the rich condition with the plugs fowling after running for only a few minutes.
This is what the plugs looked like after only a few minutes idling at about 1100rpms

[Cdnpt1]

Maybe try a hotter plug? How is the charging system?

[Guest]

How long since you actually ran it last? Did you put some sort of stabiliser in the fuel if it was a few months? Good chance the fuel has started to go off already... might be wrong but just a thought...

[apopleptic]

Charging system is good. Plugs are only a year old or so, but I'll have to do a better job of cleaning them this time or replace them. I have no idea about a hotter plug. is that a common 'mod' for these bikes? I had thought about possibly getting a pair of these but the plug manufacturer said they only made ones too hot.

Also, the petcock seems functional. fuel only flows when vacuum is applied.

The bike was last run/ridden... probably two months ago, maybe 3.
when I parked it the tank was empty, or almost completely empty. I added fresh fuel, but I suppose that there was probably some that was in the carbs as well as a little in the tank.
On the up side, I do use fuel without the ethanol so one less sin against the bike.

What concerned me the most was the fire in the airbox. It reminded me of a propane lanterns mantle the way the flame danced
I almost got to use the fire extinguisher I have in my kitchen...

If I can bring myself to do it tomorrow I am going to try to take the carb back of and check it out again.