noise from engine at idle speed

my 91 VFR makes a rather load "knocking noise" at idle speeds - seems to be much worse as the engine warms up. When I engage the clutch, the noise is dramatically reduced. If I pick up engine speed to 1500rpm the noise goes away. The bike has only 12K miles on it, I am the second owner and it has never been abused. The noise does not impact riding or engine performance but before it does.....

 

12k miles in 18 years! that sounds like abuse to me!

mine does the same thing, but it doesnt get worse as it warms up, im pretty sure its normal.

 

My 91 does the same thing - seems to be the nature of the beast. Mine is loud when it is cold and quiets down when it warms up. Comes from the clutch side of the engine and goes away when you pull in the clutch. Common consensus is the clutch basket rattling around at idle. balancing the carbs I suspect would help but I haven't acquired the tools for that job yet. Hasn't caused me any issues.

 

That's a normal noise for most bikes, as old450 pointed out. The clutch basket is typically made from aluminum, and the "driven disks" (can't remember the proper name...) are made of steel. The steel drive tabs that slide in the clutch basket wear the aluminum over time, and "rattle" back and forth as the engine RPM's vary.

A good tuneup will generally reduce the noise.

 

sounds to me like the clutch basket is worn. the plates should not be slapping around loose you may want to check it...or add slick50 it helps reduce idle noise..