Spark plugs

How do I know when it's time to change my spark plugs....does the motor act any different?

Pull plugs- check for oil deposit buildup-heat plug TIP with hand torch & clean off with wire brush & re-gap plugs if needed. Put back in outboard { lawnmower,snowblower,etc.}   Only need to buy new plugs when TIP of plug starts to wear down. Why waste money buying new plugs all the time.

I change mine every year. Cheap insurance.

No test, but like 12pack, carried new plugs and wrench in toolkit...

Inspecting the plugs when winterizing was when plug changes happened,  never kept track of time between changes 

Otherwise,  owners manual might give hours or time recommendation 

Depends, are u talking EFI or carbureted engine?  Every other year for carb engines longer on fuel injected engines. More or less depending on the amount of use. If u only use the motor twice a year u won’t need to change the plugs as often. If u do a lot of trolling at low rpm’s plugs may get fouled especially on a 2-stroke, you’ll notice a difference then. If u troll with a motor it’s a good practice to run that motor wide open for a bit once ur done trolling that will help keep the plugs clean.