[JB Yap]

Was wondering whether it's normal for Z to emit some buzzy vibration sound at certain rpm ..mine at around 6k rpm seems to buzz a little which I can't seems to find out where it comes from. Other than that..from 4 to 5 k rpm there's ntg...above 6k it's less noticeable. I read that it's a normal Kawasaki 650 twin thing to buzz a little here and there. Some thoughts would be nice. Ride safe guys.

 

[Cowasaki]

I would suspect the buzz to be coming from the Z650 if it was near the top of its rev range, but that doesn't seem to be the case.
JACoH gave a pretty good explanation of the problem and it's common with the bike.

Yes sir, welcome to the forum. Our bike is a high performance parallel twin cylinder motorcycle, which has a tendency to vibrate a bit. It is very different from a scooter, remember your Suzuki had a completely enclosed automatic belt drive system versus a chain drive on the Z. After you get a few more miles on it, it will smooth out considerably, mine took about 1500 miles. The vibration will always be there, but will be more subdued and you will get used to it. Imagine how a Harley vibrates!

 

[Tremonte]

Perfectly normal on this bike.

 

[JB Yap]

Sounds like some parts or fairing got loose at 6k rpm though...guess it's normal due to such vibey motor. It does makes the bike sounds cheaply made though. Otherwise it's terrific for commuting.

 

[hawker]

Sounds to me like the OP has a specific buzz at 6K, that is different from the normal buzziness that is part of the bike generally.
I think Tremont mentioned in one of his videos that that part of his seat cowl buzzes at a certain RPM and he tracked it down and fixed it. Tremont...a possibility?