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Discussion Starter #1
Hi All,
I have recently noticed that my Ninja 400 has developed a buzzing sound at 6800rpm. The sound comes on at these revs and diseappers when the revs rise or fall below this value. It appears on both acceleration and deceleration when pasing 6800 rpm. Appears to be engine vibration and not drivetrain related since it also happens when revving the engine in neutral or while pulling in the clutch at these revs. I would expect it is something resonating in conjunction with the engine vibrations at this rev speed.
What I have checked so far: it is not the horn, gas tank cap, clutch lever, keychain and instrument cluster. Seems to be coming from the front of the bike.
Any ideas on what this could be / where to look or any other similar buzzing related experiences?
 

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This might be a flyer out of the park, but...when I was changing out my header pipes to my full flow ones, the left side pipe where it goes into the head was loose, the two bolts were not even finger tight. The right side was tight and both were tight on my wife's ninja. I'm not sure that would make that vibration but just a thought.
 

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This might be a flyer out of the park, but...when I was changing out my header pipes to my full flow ones, the left side pipe where it goes into the head was loose, the two bolts were not even finger tight.
AMonkey.. That sounds logical and it certainly would cause a rattle. Just to clear things up, though. Were those 'finger tight' bolts found before, after, or during.. one of your package store runs for Guinnesse? I'm just taking notes for future reference here, that's all.;)
 

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AMonkey.. That sounds logical and it certainly would cause a rattle. Just to clear things up, though. Were those 'finger tight' bolts found before, after, or during.. one of your package store runs for Guinnesse? I'm just taking notes for future reference here, that's all.;)
HaHaHa!! This was way before my need to hoard Guinness...oh, wait, I have always hoarded Guinness...
 

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Discussion Starter #5
Starting to think that this is airbox resonance - can't find anything that is loose. In your Ninja 400 do you notice a change of engine sound around 6800rpm?
 

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Could be. I can try and check it out today when I go for a spin on my bike...I mean go to the grocery store.
 
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