Batemans Bay trip

Went for a spin to B-bay yesterday to catch up with a mate John that I know from i30 forum. 
He has a Harley ( late 90's soft tail ??) that's had a heap of work done on the engine. Gives it a canning at the drags. He's fired the Harley up, I started mine up and had to check if it did - couldn't hear mine over his. We get up to a servo / bike place at Lyne 15 km up the road and he asks " is it really loud ??"
( John takes both his cochlear ears off whenever he starts it and doesn't put back on until turned off. )
I replied " only when you open the throttle " 
Coming home I went to accelerate and got "burrr, burrr" and thought looks like I'll be doing the @Gus clean out. So teabag ordered, will do oil & filter & check out air filter as well.