For safe operation and to prevent any possible damage to your tool, circular saws should only be used with the size of blade specified.
Undersized blades are hazardous because the guard will not properly cover the teeth of the blade.
Larger blades will not provide enough clearance for chip exhausting and can interfere with the guards.
Please only use the size of blade specified for your circular saw since alterations may cause the tool to be unsafe and may cause the warranty to be void.