Spark plug question

[simon0867]

I've got another question for you kind people.
Can a change of spark plug change the noise of the engine?

I've noticed that the pitch of my engine seems a bit higher,  it seems sharper almost more like a 2 stroke (my bike is a 4 stroke). 
The only thing I have done recently is swap the standard spark plug for an Iridium one as I was having a few starting issues.   Had no problems since the new plug went in. 

I also wondered if there might be a small hole in the exhaust but I can't see anything. 
The bike is running as normal but I'm just curious. 

Any thoughts welcome and thanks as always. 

[90GTVert]

Maybe if the old plug wasn't igniting the mixture well, and then performance should improve too. Otherwise I can't say I've noticed a spark plug changing the pitch of the engine.

[simon0867]

Thanks, starting has certainly improved with the new plug so maybe that is the case. I'll keep an eye on things over the next few days just in case.