tractor supply has a product called Fabulous Blaster. it says "powerful lawn mower tune-up."
you spray it in the plug hole for 20 seconds, put the plug back in, and turn the motor w/out starting it. let sit for 15 minutes then start and operate.
claims to:
restore power and compression
free rings and valves
prevent vapor lock and stalling
removes moisture and smooths engine performance
removes carbon, gum and varnish deposits
cools injectors and turbos(just kidding)
works ok i guess.
i figured out that my carb was shot on my old mower. so, i took the carb off another mower, installed it, then sold it.
edit: the side of the can says it's called Blaster LMT
theholycow 
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