I'm now trying to start my GT200 after letting it sit for ages. I learnt how to get the spark plug off this weekend so I did that 1st of all. The plug looked ok and I got a spark when turning the engine over on the starter. A yellow sort of spark if that means anything.
The battery did have a load of deposits around the +ve terminal (which I cleaned off) and it took a while to charge but my charger said it was charged. It did turn the engine ok (not as lively as my GTS though) and I did get a spark so maybe the battery is fine.
I'll have a look at the air filter next. Maybe put in some new fuel.
Anything else to look for?