The Toro 521 typically uses a spark plug with the designation NGK BPR6ES or an equivalent. It's important to check your owner's manual for the specific model to confirm the correct spark plug type, as variations may exist. Additionally, ensure that the spark plug gap is set according to the manufacturer's specifications for optimal performance.
I've still got my users manual - it says the gap should be 0.030" (0.76 mm).
how to replace plug wire on a toro mower
To replace the belts on a Toro 521 snowblower, first, disconnect the spark plug wire for safety. Remove the plastic cover or housing to access the belts, typically secured with screws or clips. Carefully remove the old belts, noting their routing, and install the new belts in the same configuration. Finally, reassemble the cover, reconnect the spark plug wire, and test the snowblower to ensure proper operation.
Champion RJ18Y
.030
Tecumseh Part #611049 - Champion Spark Plug #RCJ8Y
Champion RJ19LM will work.
Get a spark plug socket and wrench that fits the plug body and remove it by turning counter-clockwise.
The correct plug gap for my Toro GTS 6.5 horse mower is 0.035
Autolite 458
.025
The spark-plug gap for a toro 6.5 hp self paced walk behind lawnmower is a 0.035 spark plug. You can easily find nice spark-plugs for sale on sites such as eBay.