Last night my bike started making a light siren or low howling sound leaving tomorrow for street vibes it's a 2000 fxst softtail Standard no idea what it would be had all oils change in the last 3 months I put a lot of money I'm to really wanting to ride to Reno any input would be nice

 

I changed the tranny lube to severe gear oil and noticed a high pitched sound like you're describing when gearing down to first gear or when moving out in 1st just after cranking a cold bike. I don't think it's loud enough for other riders to hear. Got 1500 miles on her since that change and it's still doing it. Hasn't hurt anything either !

CJ

 

Sounds exactly like mine. Harley dealer said nothing was wrong but after some slight clutch adjustment it vanished. Worth a shot