When I got my 78 xs1100 I had the bike a week an a half an the back tire was bald...I was %!¤ although I was brakin an lighten the back tire up an smokin it 4 ....3 gears hhaha when I complained 2 yamha ,not the dealer they told me that they were close 2 voidin the warrenty if I kept buggin them cause noises I heard in the motor was the other thing I was %!¤in about..anyway long story short aluminum , which basically my 78 1100 an our 1900 road / stroto´s r don´t contain noise like a steel motor an ....there´s a lotta gears in both blikes an gearrs r noisy by design ..add in air cooled an tire an drive train noise. U´ll make ur self crazy if u pay them 2 much attention. U´ll know when sumthing is falling ,bad vibration, loud whines tha change with engine rpm or bike speed [ m.p.h. ] an of course loud banks , knocks an such.....ok?