Exhaust note

Hi
Hope someone can come up with a reason for this!!!
I have recently changed the crank, bearings, rings and mag housing on my mugello 200 fitted scooter. It has been running fine for couple of weeks with a few little hiccups but all of a sudden in the last few days the exhaust note has gone from being silent but deadly to 'what the fu*k is that'!! This happened in the space of about two hours!
It has a 48 mm expansion with a home made longer silencer, not perfect but made a lovely what I call a tinny sound, now it is the loud "bop bop" sound(don't like it!!!). Have repacked end can although it looked okay, still the same, tried a repacked Stirling end can but still the same.
The noise is definitely coming out of end can, exhaust manifold has been faced so I know fits well but it is not a leaking exhaust sound!
Any ideas would be appreciated before I consider a new exhaust.
Thanks
Hope someone can come up with a reason for this!!!
I have recently changed the crank, bearings, rings and mag housing on my mugello 200 fitted scooter. It has been running fine for couple of weeks with a few little hiccups but all of a sudden in the last few days the exhaust note has gone from being silent but deadly to 'what the fu*k is that'!! This happened in the space of about two hours!
It has a 48 mm expansion with a home made longer silencer, not perfect but made a lovely what I call a tinny sound, now it is the loud "bop bop" sound(don't like it!!!). Have repacked end can although it looked okay, still the same, tried a repacked Stirling end can but still the same.
The noise is definitely coming out of end can, exhaust manifold has been faced so I know fits well but it is not a leaking exhaust sound!
Any ideas would be appreciated before I consider a new exhaust.
Thanks