Knocking at 4000 RPM

[agconor]

Hey everyone,
My Yamaha XJ600 has a slight knocking at 4000 - 5000 RPMs and goes away outside that range. I can barely hear it but I feel it. It is not strong and doesn't seem to be impacting performance. What could it be?
Cheers.

 

[scrammts]

while you are heavy n the throttle or normal?
how long (tanks of gas or just this one)?
been to an dodgy fuel stations lately?
used lower grade fuel lately?
put any additives in your fuel lately?
any new farkles on recently (tail tidy, luggage, slider)?

 

[jeffjones]

Bump up to the higher octane gas for a tank or 2 and see if it goes away, That fixes majority of minor knocks

 

[agconor]

Will try and get back to you. Thanks for the suggestions. It's only in gears 3 and up though if that makes a difference.

 

[Stewart]

open the pilot screws a half turn more