My 03 WR450 is getting really loud

[Bix Weir]

I bought this bike brand new.
I just rebuilt the engine with a 478 Big Bore as it was starting to get tired.
I went though the entire engine, new crank, all new bearings ect.
I have the YZ cam mod and a few other goodies.
But, after I got the engine rebuilt it seemed much louder.
It runs great but loud.
I have a full Yoshimura exhaust on there.
Any suggestions?

[Sandblaster]

My guess is that the muffler needs to be re-packed.
Have you ever re-packed it?

[foxx4Beaver]

just the fact that your pushin a brand new bigger bore now,will make it a touch louder....but as sandblaster mentioned,try re-packing the silencer....that should help.